Auto Service Professional - June 2021 by EndeavorBusinessMedia-VehicleRepairGroup

JUNE 2021 • VOL. 11, NO. 3

THE TECHNICIAN’S RESOURCE

ALL THE BREEDS OF HYBRIDS Understanding the different systems 5

PISTONS HAVE A RING TO THEM ANATOMY OF A WAVEFORM 5-GAS ANALYZER UNDERSTANDING CHRYSLER ESIM

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Auto Service Professional > The Technician’s Resource

For Owners

For Managers

CONTENTS

For Technicians

June 2021 Vol. 11, No. 3

Departments 06

TECH TIPS From crankshaft to torque

TECHNICAL SERVICE BULLETINS From BMW to Dodge

PRODUCTS New and innovative equipment

AD INDEX Your connection to free information

Technical 14

STRAIGHT TALK If your shop isn't providing digital inspections, it's time it did

NOT ALL HYBRIDS ARE EQUAL Understanding the different systems

PISTON RINGS Understanding these crucial parts

THE ANATOMY OF A WAVEFORM Understanding how a DSO can improve diagnostics

BENEFITS OF A 5-GAS ANALYZER A handy addition to your scan tool

CHRYSLER ESIM Understanding this system, and testing tips

COVER PHOTO COURTESY OF TOYOTA MOTOR CORPORATION

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S T R A I G H T TA L K

Digital Inspections

If your shop isn’t providing them, it’s time to shift gears

igital inspections” are all the rage these days and with good reason. During a pre-work safety inspection or as a result of diagnostics or during disassembly, the technician can easily snap a photo (or video) using a modern scan tool or digital pad device. You can then show the customer what the problem is or use a text message to the customer if the customer is at a different location after dropping the vehicle off. This offers transparency, proving to the customer a specific problem or need for repair. As a case in point, I recently observed technicians performing a safety inspection prior to installing a set of new tires. They quickly discovered a loose (and ready to separate) outer tie rod end. One of the techs immediately showed a digital photo and video of the concern to the vehicle owner, providing proof of the need for repair. While this particular shop has a glowing reputation for quality work and honest dealings, since the tech provided visual proof and a clear explanation of the hazard, the first-time customer didn’t need to wonder if she was being taken advantage of, and immediately approved the repair. The technicians also took snapshots of the vehicle’s odometer, VIN plate, checking fluid levels, tire inflation pressures, existing body damage (dents, scratches), etc, all to be stored in the customer’s file for current or future reference. Given the availability of devices that can capture images (and sound) and the ease of presenting this to the on-site customer or remotely by messaging/tex-

If your shop isn't providing a digital inspection, please consider adding this feature."

ting to customers in a heartbeat, this provides reassurance to vehicle owners in a much more direct and efficient manner as opposed to trying to explain the issue over the phone or in your shop’s waiting room and serves to increase the customer’s trust factor. Performing a digital inspection also allows you to create and maintain a visual record of the concern and repair, again which can be stored in the customer’s file. If your shop isn’t providing a digital inspection, please consider adding this feature. Shops that have adopted this customer communication process have reported a substantial increase in service sales, in many cases by as much as 70%, as well as speeding up the job process. This is a good example of how modern technology works in our favor. A plethora of available software allows seamless integration between the hand-held tool and office management, speeding up parts ordering, customer history fi les and billing.

M I K E M AV R I G I A N EDITOR

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OnlIne

THE TECHNICIAN’S RESOURCE

3515 Massillon Rd., Suite 350, Uniontown, OH 44685 (330) 899-2200, fax (330) 899-2209 Website: autoserviceprofessional.com Publisher: Greg Smith, ext. 2212 gsmith@10missions.com Editor: Mike Mavrigian, (330) 435-6347 birchwdag@frontier.com Managing Editor: Ron Ledgard, ext. 2216 rledgard@10missions.com Senior Editor & Digital Projects Editor: Joy Kopcha, ext. 2215, jkopcha@10missions.com Production Manager: Karen Runion, ext. 2210 krunion@10missions.com Art Director: Zach Pate Graphic Designer: Olivia Curti Production Artist: Lauren Coleman

CONTRIBUTORS Jeff Taylor, Diagnostics & Driveability Specialist Bill Fulton, ASE Master Tech Edwin Hazzard, Mobile Tech Specialist Jake Sorensen, McNeil’s Auto Care

ADVISORY BOARD Chris Chesney, CARQUEST Jake Sorensen, McNeil’s Auto Care Seth Thorson, Eurotech Automotive

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TECH TIPS CRANKSHAFT THRUST Engine crankshafts ride on a series of main bearings, one of which features a thrust main bearing that includes a front and rear flange that limits the amount of fore/aft movement of the crankshaft. Typically, crankshaft thrust will be specified in the 0.002- to 0.006inch range (always check the OEM specifications for the specific engine). Typically, damaged/worn thrust bearings are caused by excessive torque converter pressure, riding the clutch (if the vehicle is equipped with a manual transmission) or a damaged/ misadjusted throw-out/release bearing. To check crank thrust, mount a dial indicator to the front of the block (using either a magnetic or bolt-on indicator base). Position the dial indicator probe at the front face of the crankshaft snout (or the face of the front counterweight), making sure that the probe is parallel with the crankshaft (avoid angle contact). Preload the dial indicator to about 0.050 inch. Move the crankshaft fully rearward by placing a large flattip screwdriver between a crankshaft counterweight and a main cap, using the screwdriver as a lever, and zero the dial indicator. Carefully pry the crankshaft fully forward until it stops and note the travel reading on the indicator. Avoid excess prying pressure. If travel is greater than factory specification, the thrust bearing is worn and must be replaced.

Fig. 1

Fig. 3

Fig. 5

From crankshaft to a tow

Fig. 2

Fig. 4

Fig. 1: Depending on engine design, the thrust bearing may be located at the center or rear main bearing area. Both the upper and lower bearing shells will feature thrust faces. Note the oil grooves on the thrust face. If these are worn off, the upper and lower bearing shells must be replaced. Fig. 2: Example of an upper main thrust bearing at the center main location in a GM LS-series engine. Fig. 3: Note the shallow relief on this main cap, designed to accommodate the thrust bearing. Fig. 4: A dial indicator allows inspection of crankshaft thrust movement. The indicator plunger must be positioned parallel to the crankshaft. Fig. 5: An alternative for dial indicator placement is at the face of the front counterweight.

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TECH TIP S

TORQUE/ANGLE MADE EASY

This is what happens when the adapter is not fully threaded into the tool’s mandrel.

Whenever you’re dealing with tightening engine fasteners that require an OEM spec, involving both torque and angle tightening, there’s the hard way and there’s the easy way. Let’s say that a bolt (or series of bolts) requires an initial torque of 30 ft-lbs, to be followed by an additional rotation of 120 degrees. You can apply the initial torque value using your torque wrench, then lay that tool aside, then paint a dot on the bolt head and rotate it to what you assume to be about 120 degrees. Or after torque, you can grab an angle gauge, attach it to a wrench, zero it, and carefully rotate until you hit the 120-degree mark (depending on the type of gauge, this can often prove cumbersome). In either case, you must perform a continual turn and cannot use a wrench ratcheting feature. Either approach takes more time and can be inaccurate. The best method by far is to use a digital torque wrench that also incorporates angle tightening. Press a button to select the torque type (ft-lb, in-lb or Nm), and select the torque value. Use the wrench to apply the desired torque (with most tools), when you reach the desired torque, a visual and audible alert will notify you. Next, using the same tool, press a mode button to select angle. Then select the desired angle. Place the wrench back onto the bolt head and turn, using either a continuous pull or (depending on the features of your specific digital wrench) use a ratcheting motion. Some tools feature an internal “memory” of rotation during ratcheting, which is a nice feature. The audible and visual alert will be observed when you reach the desired angle. Currently available torque/angle digital wrenches provide both speed and accuracy.

INSTALLING HARMONIC BALANCER

HITCH RECEIVER MAINTENANCE

When installing a harmonic balancer, always use a dedicated balancer installation tool that allows you to draw the balancer onto the crank snout. Here’s a tip: when you install the adapter (the threaded adapter that screws into the tool’s mandrel and engages into the crankshaft bolt female threads), always make sure that the adapter is fully threaded into the mandrel first. If the adapter is only installed by a few threads, the force required to draw the balancer into place can easily break the female threaded end of the mandrel. If the adapter does not thread into the mandrel easily by hand, use a screwdriver to turn the adapter (the adapter has a slot) to fully tread into the mandrel.

It’s common for many of your customers’ light trucks or SUVs to be equipped with a frame-mounted hitch receiver. In many cases, the owner has installed a draw bar (with ball) into the receiver prior to a trip and has neglected to remove the draw bar after a trip. Leaving a draw bar installed in the receiver commonly results in rust issues, to a point where the draw bar has become severely stuck. Suggest that the owner first applies an anti-seize paste or other lube onto the draw bar before installation, and when not in use, to remove the draw bar. Periodic maintenance can avoid this problem by simply cleaning the draw bar and cleaning the receiver’s square port with a square bristle brush designed for this task. Whenever a vehicle enters the shop equipped with a receiver, ask if the owner would like to have it cleaned and lubed. Paying attention to this will avoid future headaches. A rusted-in-place draw bar can be stuck so severely that in some cases, the entire hitch receiver assembly needs to be replaced if the draw bar cannot be removed.

Simply cleaning a receiver with a bristle brush prior to each use can avoid big problems. Scrub to remove all rust and debris, and lube the draw bar prior to installation. Leaving a draw bar in the receiver year-round can easily cause rust seizure.

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H Y B R ID V E H I C L E S

Not All Hybrids Are Created Equal Understanding the different systems

B Y J E F F TAY L O R

HYBRID ELECTRIC VEHICLE (HEV)

vehicle relies on two different sources of power for vehicle motion: the fuel in the tank (gasoline/diesel) and an electric motor. But there are different levels of vehicle hybridization that are in production and showing up in our shops for service and repairs. There are currently five types of hybrid vehicles and three hybrid configurations being used and produced almost always combined with an Atkinson cycle engine. Recognizing the differences and characteristics of each

of these hybrid types and configurations is crucial for techs for repairs and diagnostics. And for shop owners, it helps to understand the service opportunities each will present.

HYBRID TYPES Micro Hybrid Vehicle (mHEV): This is the most basic form of hybridization but is one of the most common: the start-stop vehicle. Because the Internal Combustion Engine (ICE) is the only drive system responsible for vehicle motion,

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H Y B R ID V E H I C L E S

Fig. 1

Fig. 2

the start-stop vehicle is rarely thought of as a hybrid. During start-stop operation when the ICE is not running or stopped, it is saving fuel and tailpipe emissions. But the vehicle is still in run mode and operating off the vehicle’s 12V battery, keeping the comfort, entertainment and driver systems functional and waiting to immediately restart the ICE when needed. Most start-stop vehicles will modify the charging profile of the 12V battery by increasing the charge rate during vehicle deceleration and will use an AGM battery. The fuel savings per vehicle are low on this type of hybrid (about 1%) but it’s large enough for most manufacturers to use this form of hybridization due to its simplicity and lower initial cost. Mild Hybrid Vehicle (MHEV): The mild hybrid will have an electric motor involved in the vehicle’s drive system, but it will not propel the vehicle on its own and is only used to support the power output of ICE. The electric motor can boost the engine performance during acceleration by providing torque, eliminating the need for a traditional stator motor during start-stop operation and recuperate more energy during deceleration and braking than the mHEV can. The MHEV will have two electrical systems: a traditional 12V low voltage system and high voltage system that can range from 36V to 160V depending on the make and model. Each MHEV will have a DC-to-DC convertor to exchange energy between these systems.

Fig. 1: There are many types of Hybrids that are now entering our shops for service and almost all the services and repairs do not have anything to do with the high voltage system. Fig. 2: This is the plug-in port for a PHEV on a Toyota Prius. Most of these plugs are standardized in North America and allow the vehicle to be plugged in at home, work or other charging location.

There are two familiar types of MHEV: The Belt-Alternator-Starter (BAS) system and the Integrated Motor Assist (IMA). The BAS is considered a bolt-on hybrid solution that can be applied to almost all vehicle platforms with few modifications. The amount of torque that a BAS system can transmit is limited by the slippage of the drive belt. The IMA MHEV made popular by Honda does not suffer from this limitation because the electric motor is connected directly to the crankshaft. GM has used the BAS, and FCA (Fiat Chrysler Automobiles) is currently using the BAS on its 48V eTorque system that is an option available to Ram 1500 trucks and Jeeps. Hybrid Vehicle (HEV) or Full Hybrid Vehicle (FHEV): The HEV will use both the electric motor and ICE to provide vehicle motion. The HEV permits full electric driving but only for short trips and will take advantage of all the mild hybrid characteristics. The HEV will have a higher high voltage battery system typically 300V to 400V. The HEV will have a more powerful electric motor than that of the mild hybrid and a more capable high voltage battery for supplying and storing more energy. Toyota and Lexus have been the leading manufacturers of HEV vehicles, but the list of HEV vehicles is much bigger in 2021 with Hyundai, Ford, Audi, Nissan, Honda, Chevrolet and Kia and others all producing HEV vehicles.

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H Y B R ID V E H I C L E S

Fig. 3

Fig. 3: AGM batteries are sensitive to charge rates, the proper charger and tester must be used to ensure that they aren’t damaged when charging and diagnosed properly. Fig. 4: Most hybrid repairs don’t involve having to remove the high voltage disconnect, but if they do, the proper safety procedures must be followed.

Fig. 4

Fig. 5

Plug-in-Hybrid Vehicle (PHEV): The PHEV will share all the characteristics of the HEV but will now be equipped with a high voltage battery that can be charged at home or at other locations using a special cable and plug.

Fig. 5: All hybrids will use a 12V battery that can be located almost anywhere on the vehicle. Using an information system that is up to date will aid in the location of parts and pieces.

The PHEV can be driven in full electric mode more frequently and farther (about 45 miles) than the HEV because it has a larger more efficient battery and a more robust electric motor. Range Extender Electric Vehicle (REEV): The REEV is regarded as a series hybrid because the ICE motor is only used to power the electric generator in most applications. The BMW i3 and the Chevy Volt are examples of current models that are REEV.

HYBRID CONFIGURATIONS Series Hybrid: The ICE does not directly power the wheels on the vehicle. The ICE drives a generator that will either drive the electric motor or charge the battery pack. Parallel Hybrid: This type of hybrid has two drive systems: an ICE and an electric motor. The vehicle can be driven by just the ICE or just the electric motor or a combination of both. With the parallel hybrid the power of the ICE and the electric motor are added together to form the total power of the vehicle. Series/Parallel Hybrid: This hybrid merges the advantages and complexity of both the series and parallel systems. The combinations of both designs allow for both the ICE and electrical motor to drive the wheels (parallel) or only the electrical motor (series). Allowing for only the ICE-only or electric-only means that the ICE can operate at maximum efficiency more frequently. This translates to more series hybrid operation at lower speeds and parallel operation at higher speeds. This system is more expensive to produce, requires a larger battery, a generator, and more complex computer controls for seamless operation. But it is more efficient than either the series or parallel systems when used alone. This design has been made popular by Toyota and was first used on the Prius. Atkinson Cycle Engine: Atkinson cycle engine uses the same four strokes as the Otto cycle engine does, but it leaves the intake valves open 20% to 30% longer during the intake stroke. By delaying the closing of each intake valve, the intake stroke becomes longer than the compression stroke. This increases thermal efficiency, reduces fuel consumption, and lowers exhaust emissions. But delaying the closing of the intake valves closing comes at a cost. The Atkinson engine suffers from poor low-speed torque and weak throttle response. To compensate for this deficiency the electric motor will

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H Y B R ID V E H I C L E S

Fig. 6

provide the low-end torque and power to alleviate this problem. The combination of the efficient Atkinson cycle engine with an electric motor is ideal for hybrid vehicles and is an amazingly effective pairing that results in good fuel mileage and driveability.

SERVICE OPPORTUNITIES There are many similar services and repairs on hybrids that are similar to non-hybrid vehicles. But some may require removing disconnecting the high voltage battery, such as an AC compressor replacement. This is when we need to talk about safety. Safety: Following the step-by-step instructions and using the proper approved and tested safety equipment is imperative if you are dealing with the high voltage system. Take the time to read any service precautions fully to familiarize yourself with what needs to be done to safely the service vehicle. The proper safety equipment and following the proper procedures cannot be stressed enough. Servicing an AC compressor that is run by the high voltage system will require the high voltage battery to be disconnected using the service disconnect procedure. All the service information steps must be followed to ensure that all the voltage is removed from the system before starting the repair. All hybrids are going to have a 12V battery. Normally, a hybrid will use an AGM 12V battery, and they need to be treated differently from traditional lead acid bat-

Fig. 7 Fig. 6: Hybrid cooling systems are specialized, and if service is performed, a vacuum filler system is the factory recommended tool. It will ensure that all the air is removed, even from the exhaust heat exchanger like the one on this 2021 Ford Escape Hybrid. Fig. 7: You can see the two degas cooling system bottles also on the 2021 Ford Escape. The hybrid cooling system does have a service interval that should be followed.

teries. AGM batteries have a low internal resistance and are sensitive to charging voltages and charging rates. The proper battery charger and test equipment must be used for accurate test results and charging. All current hybrids will have some form of ICE that will need to be serviced and repaired. They will need oil changes, filters, spark plugs and other repairs. The diagnostics and repairs of these engines are generally the same as a non-hybrid engine but getting the hybrid ICE to stay running during a diagnostic is a common issue that arises, even if it’s just to warm the ICE up for an oil change. Keeping the ICE running typically requires entering a maintenance mode. Getting a Toyota or Lexus into maintenance mode can be done by one of two ways: using a scan tool and enabling maintenance mode or by doing the shifter pedal dance. The procedure is as follows. Perform the following steps within 60 seconds. 1. Turn the power switch to run without pressing the brake. 2. Fully depress the accelerator pedal twice with the shift lever in P (no brake pedal). 3. Press the brake and shift to N and fully depress the accelerator pedal twice. 4. Press the brake and shift to P and fully depress the accelerator pedal twice. 5. Check that MAINTENANCE MODE is displayed on the information display.

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H Y B R ID V E H I C L E S

Fig. 8

Fig. 9

Fig. 8: This is the high voltage connector on the AC compressor, if the compressor needs to be replaced or removed the high voltage service disconnect will have to be disconnected following all the proper procedures. Safety is paramount. Fig. 9: There are occasions when the engine needs to be kept running for diagnostics or after a repair. Entering maintenance mode is the answer.

Fig. 10

Fig. 10: When the water pump was changed on this Lexus hybrid, maintenance mode was entered to ensure the proper engine warm up and circulation of the cooling system occurred.

TYPE OF VEHICLE

ENERGY SOURCE

PROPULSION DEVICE

ICE Internal Combustion Engine

100% Fuel

100% ICE Propulsion

mHEV Mild Hybrid Electric Vehicle

99% Fuel 1% Electric Energy

100% Ice Propulsion

MHEV Mild Hybrid Electric Vehicle

80-90% Fuel 10-20% Electric Energy

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HEV Hybrid Electric Vehicle

70-80% Fuel 20-30% Electric Energy

70-80% Fuel 20-30% Electric Motor

PHEV Plug-In Hybrid Vehicle

60-70% Fuel 30-40% Electric Energy

60-70% Fuel 30-40% Electric Motor

REEV Range Extender Electric Vehicle

80% Electric Energy 20% Fuel

100% Electric Motor

6. Start the engine by turning the power switch on (READY) while depressing the brake pedal. MAINTENANCE MODE should still be displayed on the information display. After maintenance mode is entered, the idle speed will be approximately 1,000 RPM with the shift lever in park. The engine speed will increase to 1,500 RPM when the accelerator pedal is depressed halfway with the shift lever in park. If the accelerator pedal is depressed more than halfway, or when the accelerator pedal is fully depressed, the engine speed increases to approximately 2,500 RPM. Cycling the ignition switch will take the vehicle out of maintenance mode when done. Note: This procedure has worked for me as well on Honda and Hyundai hybrids, but if in doubt look up how to enter maintenance mode in your information system. Cooling system repairs are another area that is often overlooked when it comes to hybrids. HEV and PHEV will often have a separate cooling system for the generator, invertor and electric motor and other parts that need thermal management. This cooling system

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has a service life and a service interval. Toyota/Lexus want the invertor coolant changed at 150,000 miles and when doing so they recommend the use of a vacuum filler to ensure all the air is removed. The BAS hybrid is dependent on the serpentine belt and tensioner for power transmission. The older GM BAS requires the use of a special tool to remove or install the belt that was under heavy tension. The current eTorque that FCA is using does not require any special tools other than a ½ inch breaker bar to release the tension. Thermal management of the hybrid battery is important. Most hybrid batteries are air cooled using a blower motor that will force air over the high voltage battery pack to maintain the proper temperature. These motors must be kept clean and free of debris. On early Toyota/Lexus hybrids, only a grate was used to stop large debris from entering the battery’s forced air cooling system and these could plug up and lead to the overheating of the battery or cooling fan failure. Toyota is now using a filter system like a cabin air fil-

ter to deliver clean filtered air to the battery pack and recommend that it is checked at every service interval or sooner (3,000 miles). They have even issued a TSB T-SB-0062-20 and a Tech Tip # T-TT-0432-17 that addresses the issue on most of their vehicles. There are many valuable services that can be performed on hybrids without a lot of specialty equipment. Not all hybrid vehicles will have a high voltage battery, but they will all have a 12V battery and some form of ICE engine that will need to be serviced and diagnosed at some point over its lifetime. Hybrid cooling system services, air filtration, and specialized belts and tensioners on BAS hybrid will all need to be serviced at some point. Jeff Taylor boasts a 34-year career in the automotive industry with Eccles Auto Service in Dundas, Ontario, as a fully licensed professional lead technician. While continuing to be “on the bench” every day, Jeff is also heavily involved in government focus groups, serves as an accomplished technical writer and has competed in international diagnostic competitions as well as providing his expertise as an automotive technical instructor for a major aftermarket parts retailer.

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P I S T O N R IN G S

Understanding the role of these critical components

B Y M I K E M AV R I G I A N

GETTY IMAGES

Piston Rings ASP | JUNE 2021

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P I S T O N R IN G S

VEN IF YOUR SHOP DOES not rebuild engines on a routine basis, it’s beneficial to gain an understanding of the role that various engine components serve. In this article, we’ll discuss piston rings, their purpose and tips on ring service. Piston rings, in simple terms, are the components that form the dynamic seal between the piston and cylinder wall. Consider, for example, that the rings must provide both a sealing function and an oil control function, in a range of conditions and temperature extremes — from winter-morning cold starts to prolonged highRPM, high-load operation in hot weather. Also consider that most pistons “move” and “grow” laterally within the cylinder during operation, creating a sometimes unpredictable sealing area and contact surface. It should be obvious that long-term wear of cylinder walls and rings can create ring sealing and blowby issues, even a new OEM engine can experience issues if the rings were not manufactured properly. As a case in point, KIA recently issued a problem with oil rings in some 2020-2021 Soul and 2021 Seltos 2.0L engines. Apparently, the oil ring rails were not heat treated properly, resulting in excessively hardened rails, causing excessive wear on the cylinder walls. This has the potential for excessive oil consumption, exhaust system/ converter damage, and minimizing available oil for the rod bearings. Virtually all current automotive applications feature three rings per piston. The top ring is exclusively a compression ring, meaning its function is to seal the expanding combustion gases above the piston. Without an effective combustion seal, of course, these gases would leak around the sides of the piston, resulting in a power-robbing process known as blow-by. The top ring is sealed against the cylinder wall and the lands of the ring groove by the pressure differential created during the piston’s combustion cycle. As pressure increases above the ring and between the ring’s inside diameter and the piston groove, the ring is forced downward and outward, creating a tight seal over a wide range of engine RPM. The primary job of the top ring is to serve as a compression seal. It also helps to protect the second ring from combustion heat. Most modern OE compression rings feature a premium grade cast iron, ductile iron or steel alloy coated either with a heat-resistant graphite, plasma-molyb-

Fig. 1: Cross-sectional view of ring-to-piston identity and dimensional reference. Note how the oil ring expander causes the upper and lower oil ring rails to cock at slight angles to aid in sealing during up/ down strokes.

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P I S T O N R IN G S

Fig. 2

Fig. 3 Fig. 2: When measuring the gap for top or second ring gap, the ring must be placed squarely in the cylinder bore. A quick and easy way is to use a ring squaring tool which is adjustable for bore diameter. Place the ring into the bore, about a quarter-inch or so down from the deck, and insert the squaring tool. The ring is immediately leveled in the bore. If the ring is not level, your gap measurement will be inaccurate. Fig. 3: Using a feeler gauge, measure the existing ring gap. Compare this to the OEM or piston maker’s specification (gaps will often differ between top and second rings).

denum or chromium facing material. Graphite and “plasma-moly” are relatively soft and porous ring facings with excellent oil carrying capacity and comparatively fast conformability (or break-in) to the cylinder bore surface. Chrome, used today primarily by overseas OEMS, is a much harder, non-porous material. The second ring, although commonly referred to as a compression ring, primarily functions as a final oil control (about 80% of the second ring’s duty is oil control and about 20% for compression control). The two common designs are RBT (reverse-twist, taper face and a THG hook groove, sometimes called a Napier ring). The reverse twist, taper faced second ring is very common in performance ring sets. An inside bottom bevel causes torsional twist in the ring. The twist prevents oil migration from creeping up behind the second

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P I S T O N R IN G S

Fig. 4: When dealing with an OEM engine, the need to file-fit top and second rings will be rare, but depending on the application, this might be required. For file-fit rings (where the existing gap is too tight), the ends of the ring must be filed squarely. A ring filer makes the job easier and more precise. Don’t get carried away. File a bit, clean the ring, re-check the gap in the bore and continue the process in small increments until you achieve the desired gap. Remember to check the gap (and correct where needed) at each cylinder, and keep each ring dedicated to the cylinder in which it was checked and fitted. Small variances in cylinder bores might exist, so for tailor-fit ring gaps, dedicate each ring to one cylinder (fit the top ring for cyl 1, then top ring for cyl 2, etc. for all cylinders; then fit the second ring for cyl 1, then cyl 2, etc.). Keep rings organized per cylinder location. There is never any need to file fit oil ring rails.

ring. The taper face scrapes oil from the cylinder wall for oil control. Most RBT second rings are made from grey cast iron. THG second rings also feature a twist, but with no inside bevel and no taper. Instead, THG features a hook groove on the bottom O.D. THG rings offer slightly better oil control than RBT. THG also acts as a check valve to relieve excessive combustion pressure built up under the top ring, helping to stabilize the top ring (avoiding or minimizing ring flutter). Like the top rings, OE second rings are typically coated with a phosphate or plasma-molyfacing to protect the rings from combustion-related heat. These rings usually also feature a low-tension, tapered face designed to reduce drag while maintaining the ring’s oil control capabilities. Most major OE and aftermarket suppliers build a reverse torsional twist into the second ring to create a more effective seal at the piston land, preventing oil migration behind the ring. The third ring assembly serves as an oil control ring package that essentially removes oil from the cylinder wall during the power stroke. Oil control rings feature multiple components, including an expander, or spacer, and upper and lower scrapers (rails). The oil rails in this classic design rest on angled expander pads, which deliver both lateral and vertical force to seal the top and bottom surfaces of the ring groove. Oil rings are offered in standard-tension (for most street applications, and high-output engines susceptible to bore distortion) and low-tension designs. Standard-tension rings apply around 21 pounds of tangential pressure against the cylinder wall. Lowtension designs apply about 15 pounds of tension. The oil ring rails “scrape” excess oil from the cylinder walls and serve to provide oil control. If the oil ring rails are worn or are too hard and apply too much pressure against the walls, oil blowby can occur, allowing oil to escape into the combustion chambers, fouling spark plugs and potentially contaminating the exhaust stream and result in catalytic converter damage.

RINGS AFFECT ENGINE PERFORMANCE

Fig. 5: If rings are file-fit, carefully dress the filed edges to remove any burrs.

The greatest level of friction that occurs in an internal combustion engine is created by the piston rings rubbing against the cylinder walls. This friction has a direct contributor to engine operating temperature. If burnt oil/smoke occurs exiting the exhaust, this might be the result of oil passing through worn valve

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guides/valve seals or passing by the rings. A compression and cylinder leak-down check can confirm ring function. If a piston dome appears to be washed on edges or across the dome, oil is likely leaking past worn or stuck rings, which might throw misfire codes P0301P0312, in addition to experiencing a reduction of engine power due to a reduction of cylinder pressure. If oil ash is accumulated on one side of the spark plug, it is likely that oil is passing through valve guides or seals.

RING END GAP The best way to start a debate among engine builders is to ask whether an end gap is necessary in the second compression ring. The fact is, however, that virtually every North American engine manufacturer has determined that an increase in end gap in the second ring actually improves sealing performance. This is due to what’s known as the “Pressure Balance Theory.” Without a

second-ring end gap, gases become trapped between the second and top rings. As the piston moves through its power stroke, the buildup of these gases actually lifts the top ring off its land. This, of course, causes extreme blowby and power loss. Usually measured at a depth of 1.00 inches from the top of the cylinder wall, the ring gap is the installed space between the ends of the rings. When measuring end gap, the ring must be placed in the cylinder, at an equal depth along the entire perimeter. This is called “squaring the ring.” If the ring is not placed at an equal distance from the block deck, this will result in incorrectly measuring the end gap. With the ring properly installed in the bore, use a clean flat feeler gauge. The gauge must fit snugly in the gap without the need to apply much force. Always follow the piston maker’s recommendations for top and second ring gap, as this will vary depending on piston material, bore diameter and application (naturally aspirated, forced induction, nitrous injec-

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P I S T O N R IN G S

Fig. 6

Fig. 6: With the oil ring expander in place, install the lower oil ring rail, making sure that the ends of the expander butt together and don’t overlap. With the lower rail installed, this will capture the expander. Next, install the top rail. The second compression ring is installed next, followed by the top compression ring. Fig. 7: Depending on the application, top and second rings will feature orientation marks, This might include a dot or (for the top ring) the word “top.” Typically a ring that features a dot must be installed with the dot facing upwards.

Fig. 7

tion, etc.). While you must always refer to factory specifications, for street applications, a rule of thumb is to allow about 0.0045-inch end gap per inch diameter of the cylinder bore. For instance, a 4.000-inch bore might require a ring gap of 0.018-inch. In cases where the bores are a bit worn or if the block has been oversize bored and honed, rings for popular applications are available in sizes to accommodate this (3mm oversize, 0.010-inch oversize, 0.030-inch oversize, etc.). Never assume that replacement rings will provide the proper end gap out of the box. Always perform a gap check to verify this. In some cases, only “file to fit” rings might be available, wherein the top and second rings are made with a negative or zero gap, which then requires the installer to file the ends in order to obtain the proper end gap. This must be done carefully, using a dedicated ring bench-mount ring filer tool. Material removal must be kept “square” meaning that you must avoid creating unwanted angles. The width of the installed gap must be the same from inboard to outboard of the gap. File carefully, counting the number of strokes during filing, and re-check. In order to avoid removing too much material, file a few strokes, re-check the end gap in the bore, re-file, check, etc. until the correct gap is achieved. If you file too much, the ring is not usable. Once the desired gap is obtained, the filed ends must be carefully deburred using a small, flat, fine file. If file fitting is required, this only applies to the top and second rings. Oil expanders and oil rails are produced for specific bore sizes (standard or specific oversizes) and do not require file fitting.

PISTON RING TRENDS The trend in ring design today focuses on reduced friction and high ring conformability. As ring-to-cylinderwall friction is reduced, horsepower is freed and fuel economy is increased simply due to a reduction in parasitic drag. Ring “conformability” refers to the rings’ ability to seal within a bore that is not perfectly round (as often occurs when a bore is distorted during heat cycles and the stress of head bolt clamping). Ring sealing naturally affects power output, emissions control and oil consumption. This brings up yet another valid reason to use cylinder head torque plates when boring & honing a block.

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If a torque plate is not used during bore machining, you will create a round bore under static conditions, yet the bore may distort and go “out of round” once the cylinder head is bolted to the block. Of course, the extent of this distortion is dependent on the particular block in question (some will distort more than others). The point is to make the bore as round as possible when in use. If the bores remain true while the pistons run through their cycles, the more easily the rings can perform their sealing jobs. Today’s rings are becoming thinner and narrower, in part to promote conformability. Efficiency, fuel economy and reduced emissions will remain the target goals of engine designers for years to come, and it’s certain that ring size, weight and the ability to seal will continue to evolve accordingly. As engines continue to be designed as smaller and lighter packages, block decks are becoming shorter and pistons are downsizing. The result: Rings are becoming thinner, in the area of 1.2mm, with 3mm oil

rings common. Ring locations have gradually moved upward toward the piston dome. This trend is likely to continue for several reasons, including both performance and emissions concerns (for example, a smaller “crevice” volume … the circumferential void area between the piston and bore, above the top ring ... is beneficial in reducing unburned hydrocarbons). Also, regarding fuel economy, rings are becoming narrower, radially, in an effort to reduce ring-to-wall friction. The reduced dimension also allows the rings to be more comfortable (flexible) to the shape of the bore. This allows the use of lighter ring tension, providing the bore geometry is correct. Ring makers typically like to see bores finished with 280-grit stone. Coated rings are pre-lapped now, so you don’t need to create a rougher surface in the bore. This applies even to chrome plated rings. Today, there’s no need to provide a rougher bore finish in order to achieve break-in.

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P I S T O N R IN G S

RING INSTALLATION TIPS

Fig. 8: Currently available ring compressors that feature a tapered inside diameter are far better choices as compared to the old “barrel band“ style tools. The tapered inside walls compress the rings prior to entering the bore, making the task much easier and serve to greatly reduce the chance of ring damage. The tapered compressors are available in billet size-specific models (as shown here) or as split designs, allowing a range of bore size adjustment.

Before installing rings onto the pistons, make sure that the piston grooves are absolutely clean and free of any burrs. Installing rings on pistons is not difficult but care must be taken to avoid deforming or breaking a ring. This is especially important when dealing with second and top rings. Install the oil ring expander first, making sure that the ends remain butted at all times. Install the lower oil rail to capture the lower indent of the expander, then install the upper rail. Oil rails might be installed by spiraling them on by hand. Unless you’re dealing with very light tension rings, always use ring pliers to install rings on to the pistons. Winding a second or top ring onto a piston can easily create a helix in the ring, resulting in ring distortion that might not recover. When using ring pliers, expand the rings only far enough to install. Pay strict attention to all ring end gap locations. The goal is to prevent end gaps from being aligned to each other, which will create leak paths. Ring gap orientation may be specified depending on piston or OEM recommendations. As but one example, following is a recommendation for ring gap orientation. Again, OEM specifications may differ. Viewing the piston from overhead, with the front of the piston (facing the front of the engine) at 12 o’clock, end gap orientation is as follows: • Oil expander (butted ends) … between 2 and 4 o’clock • Bottom oil rail gap … 10 o’clock • Top oil rail gap … 7 o’clock • Second ring gap … 9 o’clock • Top ring gap … 3 o’clock During engine operation, rings will likely rotate slightly, but the idea is to keep gaps far enough apart so that they cannot align. In order to install the connecting rod/piston assembly into the block, the rings must be compressed in order to enter the bores. While adjustable “barrel” style ring compressors do work, billet tapered ring installers are by far the best to use. These feature a tapered inside diameter with a larger top entry and bore-size-compatible bottom diameter (squeezing the rings as the piston moved through the compressor).The downside is that

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P I S T O N R IN G S

Fig. 9: Make sure that the bore is clean. Apply oil to the bore, the ring package, piston skirts and inside the ring compressor. Verify orientation of all ring end gaps to avoid gap alignment. With the upper rod bearing installed to the rod, slip the rod/piston through the compressor until the ring package is captured, making sure that the piston skirts are exposed. Shown here is a tapered adjustable ring compressor. The compressor’s split gap and worm drive clamp allows bore diameter adjustment for a small range of bore size.

Fig. 10: Insert the piston skirts into the bore and allow the bottom of the compressor tool to firmly contact the block deck. Using finger pressure, push the piston/ring package into the bore until the ring package is fully inserted in the bore.

most tapered compressors are made with a specific bore diameter in mind, requiring separate compressors for different sized bores. However, tapered compressors are also available that offer a range of bore diameter adjustment, reducing the number of compressors required in the shop. Rotate the crankshaft to place the target rod journal near its bottom-dead-center location. Apply engine oil or bearing lube onto the upper rod bearing. After applying engine oil to the installed rings, piston skirts, the inside of the compressor and the cylinder walls, insert the connecting rod and piston skirts into the compressor. Carefully manipulate the rings until they are all captive within the compressor, with the piston skirts exposed below the bottom of the compressor. Lower the rod into the bore and allow the piston skirts to enter the bore, as well. Making sure that the bearing-equipped rod is aligned with the crankshaft rod journal. While holding the bottom of the compressor firmly against the block deck, push the piston into the bore using hand pressure, applying alternating pressure at the front and rear of the piston dome. If you feel a dead stop, try gently tapping the piston using a clean plastic piston hammer. If more force is required, chances are a ring has contacted the block deck. Never apply excess force by hitting the piston. If in doubt, raise the piston and compressor and start over. Once the top ring enters the bore, remove the compressor tool. While guiding the connecting rod onto its journal, use aplastic piston hammer to gently tap the piston until the upper rod bearing makes full contact with the journal, at which time you can install the lower bearing equipped rod cap. Tighten the rod bolts to specification. As far as the use of synthetic oils and other ultraslippery materials are concerned, Don’t use a full-synthetic assembly lube or oil at the ring-to-cylinder wall in a fresh engine that features newly-honed cylinder walls. If the lube is super-slippery, the rings might take much longer to seat, or they may not seat at all. Unless otherwise specified by the OEM, for initial breakin, it’s best to use a petroleum-based engine oil. Once the rings are properly seated (depending on cylinder wall surface finish, this might take anywhere from 30 minutes to several days), change the oil and filter and replenish with the oil of choice.

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WAV E F O R M

SNAP ON SECONDARY KV PROBE & SYNCH

that using scan data alone is basically back door diagnostics, meaning that the data we see, although mostly reliable, is basically homogenized has-been information. There are times when we need to go into the front door of diagnostics and look at the raw waveform. In this example we want to bring some awareness to the credible use of the DSO (digital storage oscilloscope). First and foremost there are 4 cardinal fundamental rules in order to master the use of the DSO. 1. THE TRIGGER LEVEL: This is where many technicians get discouraged because the waveform is not stable or walking across the screen. For example, if you are scoping out the secondary ignition system and looking at a 10 KV event, it would be necessary to set the trigger level at about the 4 KV point. Another example might be when scoping out a DREF or RPM signal for integrity we would set the trigger level at about the 2.5 volt level considering that the signal is a 5V/0V toggle.

Fig. 1: On a distributor-equipped engine, the secondary KV probe is clamped around the coil wire, and the synch probe would be clamped around the #1 plug wire.

The Anatomy of a Waveform Understanding how a DSO can improve diagnostics

B Y B I L L F U LT O N

OU HAVE CERTAINLY HEARD THE

phrase that “a picture is worth a thousand words of information.” That especially is true on lab scope waveforms from both sides of the ignition system as well as input sensors and output devices. Although our scan tools are still our No. 1 diagnostic weapons of choice, we sometimes realize that there are some severe limitations on the data. Someone once said

2. THE TRIGGER SLOPE: The cardinal rule here is that if the output device, for example an injector, which in most cases is ground side controlled by the PCM, we would then set the trigger slope to the negative side. Another example would be when looking at a secondary firing event we would set the trigger slope to the positive side. We will look at the secondary in detail later. Most secondary firing events are negative firing events. When we use the invert function of the scope in this example we also invert the trigger slope function. 3. THE TRIGGER MODE: Typically, there are two modes: automatic and normal. When selecting the automatic mode, a trace will be on the scope’s screen. This is where you would want to vertically align the trace to the ground tick mark. When viewing a signal the trigger level must be set at a proper voltage level in order to view a stable signal horizontally. The normal scope mode will only display a waveform when the signal crosses a specific preset trigger level. This mode is best used when viewing a signal drop-out or glitch detection. Many DSOs have a record function for play-back purposes to confirm a signal drop out. There are some premium DSOs that have a free run mode where the trace is constantly moving across the screen and no trigger level is re-

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WAV E F O R M

UNIVERSAL KV PROBE

UNIVERSAL COP WAND

Fig. 2: We can use a single trace example from a DSO on the lab scope side and view secondary one cylinder at a time on a DIS system or on an engine equipped with COP coils. Here, we use the universal KV probe on the secondary lead. Fig. 3: Here, we use the COP wand instead of the KV probe.

quired. This is a valuable function for a TPS sweep check or by viewing the O2 sensor activity. 4. TRIGGER SOURCE: You must tell the DSO what channel input that you want the scope to use for a trigger input. If you are using a single channel, for example channel 1, the scope’s trigger input would need to be set for that channel. If you are doing a dual trace test, for example the CKP and CMP inputs, you can select either channel input for a trigger source. We will demonstrate these fundamentals during our screen captures. These four fundamental rules once learned will be etched into your long term memory. Measurements on scope waveforms are often a necessity. On the vertical scale, there are eight squares or major divisions. Inside each major division are five minor divisions. The vertical major and minor divisions are used to measure a voltage value. If the voltage setting is 5 volts per division, then the ability to see 40 volts on the screen is available. If using a universal secondary KV probe or a COP wand with attenuation factors of 1,000 to 1, then a 1 volts per division becomes 1 KV per division. This is a popular voltage per division setting when looking at a secondary event with a DSO. The horizontal scale is used

ANATOMY OF A SECONDARY IGNITION WAVEFORM

Fig. 4: It is vitally important to know the critical points of the waveform. More diagnostic information is available by viewing a secondary waveform.

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to measure time. There are 10 major divisions on the horizontal square. Inside each major division are five minor divisions. If the time base is set at 1 millisecond per division, then the total time base on the screen is 10 milliseconds. When viewing a secondary event a 1 millisecond time base is usually ideal when viewing a single cylinder firing event. Many of the premium DSOs such as the Snap on Modis, Verus and Zeus are a combination of a DSO and an ignition scope, as well as the Bosch 5200. What this means is that when selecting the ignition scope function, you can punch in the firing order and view each cylinder’s firing events individually or view all cylinders together in a superimposed pattern or a parade pattern or a raster pattern. These functions were very popular on the distributor equipped engines. The Secondary KV probe is clamped around the coil wire and the synch probe would be clamped around the #1 plug wire as seen in Figure 1. The critical point here is that we can use a single trace example from a DSO on the lab scope side and view secondary one cylinder at a time on a DIS system or an engine equipped with COP coils. Using this approach with the DSO, we can use the universal KV probe in Figure 2 on the secondary lead or use the COP wand as seen in Figure 3. Both of these probes have an input impedance of 1,000 to 1. This means that if the DSO is set at 1 volt per division the probes input impedance is now 1 KV per division on the vertical scale on the DSO. Again we will demonstrate this during our screen captures. Let’s begin with the all important check of secondary ignition. One popular automotive technical instructor made this statement, “There is more diagnostic information from viewing a secondary waveform than any other waveform from the internal combustion engine.” First and foremost, it is vitally important to know the critical points of the waveform as indicated in Figure 4. Have you fixed engine misfire codes by simply removing and replacing worn or carbon impregnated spark plugs? Did you need proof that the worn spark plugs were in fact the cause of the misfire? This critical point is to view the spark duration period during park idle/ no-load conditions. Let’s say that the time base on the scope is set to 1 millisecond per division and the spark duration period measures below 1 millisecond.

GOOD SPARK DURATION PERIOD ON A CHRYSLER COP SYSTEM

Fig. 5: This secondary ignition waveform was captured from a Chrysler COP-equipped engine after spark plugs were replaced, indicating a good increase of spark duration with the new plugs.

5.4L COP PRIMARY MULTI-SPARK SYSTEM

Fig. 6: Ford systems multi fire the coils below 1,000 RPM. If we add all three spark duration periods together we end up with over 1.5 milliseconds of total spark duration times. In offidle under-load, the mixture is enriched which helps to increase spark duration.

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WAV E F O R M

After replacing the worn spark plugs, the spark duration period now measures over 1.5 milliseconds with no more misfires. Figure 5 indicates the good increase of the spark duration period with the new spark plugs. This secondary ignition waveform was captured from a Chrysler COP-equipped engine after the plugs were replaced. There have been many times when we print a before and after hard copy to show the vehicle owner. A main reason that we need to examine the spark duration periods is that during park idle/no-load conditions the mixture is relatively lean and compression values are less that half the values as during a WOT cranking condition. When the engine comes into an off idle acceleration mode, the compression values drastically increase and spark timing is momentarily retarded causing a higher KV demand and a shorter spark duration period. With extremely lean conditions at idle/no-load conditions, the non conductive air molecules make it more difficult to create the flame kernel. Of all the different ignition systems that I have scoped out, I have found that the GM Type II DIS ignition systems have the shortest spark duration periods of barely more than 1 millisecond. The distributor equipped engines from GM and other makes will maintain a 1.5 millisecond duration period during park idle/no-load conditions. The COP systems will be in the 1.5 to 2.0 millisecond area. These values were all captured during park idle/noload conditions. The healthy spark duration period on the COP systems is due to the fact that there is only 1 air gap being the spark plug air gap. This is why the Ford systems multi fire the coils below 1,000 RPM. See Figure 6. If we add all three spark duration periods together, we end up with more than 1.5 milliseconds of total spark duration times. In off-idle, under-load conditions, the mixture is enriched with more conductive fuel molecules which helps to increase the spark duration period. Above 1,000 RPM, the Ford systems will revert back to a single firing event. When scoping out the secondary circuit on a DIS system, keep in mind that half of the cylinders are fired negatively while the other half are fired with positive polarity. The point here is that the scope input inverse function must be used when viewing a

SECONDARY LEADS TO SCOPE CHECK SOME COP IGNITION SYSTEMS

Fig. 7: Some COP coils are heavily potted, resulting in a weaker magnet field, making it difficult to obtain a s=good secondary waveform. The key is to use a secondary lead between the COP coil and the spark plug.

SECONDARY RASTER (LEAN CYLINDER)

Fig. 8: Here, we see a lean density misfire on a distributor equipped engine using the raster pattern from the ignition scope side of the DSO. Notice the short spark line that is bending upward with an excess amount of turbulence on #6 cylinder.

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negative firing event. The COP systems and the distributor equipped engines also conduct negative firing events in the secondary circuit so you must also use the invert function when using a DSO. With early Ford and Chrysler COP systems, the COP wand is laid right on top of the coil to obtain a stable secondary ignition waveform. The later years, the COP coils on Ford systems were more heavily potted resulting in a weaker magnet field, which made it more difficult to obtain a good secondary waveform. This also applies to other COP systems such as the Asian and GM systems. The key here is to use a secondary lead between the COP coil and the spark plug. Pico supplies these leads and by using the universal secondary KV probe clamped around the lead we can now view a good secondary waveform from these heavily potted COP units. The secondary Pico COP leads can be seen in Figure 7. The important point here is that we primarily focus on the sparkline characteristics in three areas. 1. Length of duration during park idle/no-load conditions. 2. The sparkline angle during idle no-load conditions as well as during a power brake condition, 3. The presence of turbulence on the sparkline and sparkline angle during idle and power brake conditions. Turbulence on the sparkline is an indication of cylinder compression and cylinder pressures. A sparkline that shortens and bends upward with a lot of turbulence during a power brake condition is an indication of a lean density condition or a lean density misfire. As we will demonstrate these for you with screen captures, you will see that the sparkline characteristics represent our electronic window inside the combustion chamber to isolate a lean density misfire, a rich density misfire as in a fouled spark plug and a low compression issue. All of these factors also include a problem in the secondary circuit such as an open spark plug or an open spark plug wire as well as a shorted secondary lead. Internal coil carbon tracking problems that tend to be common will also be seen on the sparkline. A critical point here is that when using a DSO to scope trace the secondary events is to always use the peak detect function of the scope. Let’s take a look at a lean density misfire on a distributor equipped engine during a light power brake

#1 SECONDARY DURING LOAD

Fig. 9: A capture from a Ford COP system showing a rich density misfire from a fouled spark plug. Note, the slumping downward spark line voltages.

TOYOTA 2.4L (INTERMITTENT MISS/BUCK)

Fig. 9B: On a distributor equipped engine, there are two air gaps in the secondary circuit … the spark plug air gap and the rotor air gap. This figure shows a very short spark duration period.

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WAV E F O R M

condition in Figure 8 using the raster pattern from the ignition scope side of the DSO. Notice the short spark line that is bending upward with an excess amount of turbulence on #6 cylinder. On the opposite problem, let’s look t at a rich density misfire from a fouled spark plug in Figure 9. Notice the slumping downward spark line voltages due to high concentration of conductive fuel molecules inside the combustion chamber. This is an indication of a fouled spark plug, as well. This was captured from a Ford COP type system using a COP wand and the DSO side of the scope. How do we scope out Toyota distributor equipped engines when there is no coil wire and the coil is inside the distributor cap? We simply use the universal KV probe clamped around the coil tower. The vehicle has a misfire under light load conditions. The spark plugs have been replaced with no improvement. Remember on distributor equipped engines there are two air gaps in the secondary circuit ... the spark plug air gap and the rotor air gap. Figure 9B shows a very short spark duration period. Figure 9C shows a major improvement after the distributor cap and rotor were replaced. Cylinders with low compression will be indicated by low firing KVs and a long sparkline that lacks turbulence as indicated in Figure 10. This was captured from a GM system with the Coil Near Plug system. The COP wand was laid against the short secondary lead. Going back to using the ignition scope side of the Modis, let’s look at a 5.7L Vortec engine in a Chevy Express Van with an intermittent misfire and stall symptom. On this distributor equipped engine, we clamp the secondary KV probe around the coil wire and the synch probe around the No. 1 secondary lead. We punch in the engine’s firing order and proceed. Let’s look back to our earlier picture in Figure 4, on the critical points on a secondary waveform. Notice the point of primary turn on. Now let’s look at a secondary parade pattern from the Express Van in Figure 11. Did you notice the missing points of primary turn on? We all know that the PCM uses the DREF (digitized reference voltage) or RPM signal to determine when to turn on and charge a coil and when to turn off and fire the coil. We would suspect a faulty CKP signal as indicated in Figure 12. These systems are known to have mechanical interference between the tip of the

TOYOTA SECONDARY (AFTER NEW CAP & ROTOR)

Fig. 9C: This figure shows a major improvement after the distributor cap and rotor were replaced.

2002 SILVERADO #1 CYLINDER SECONDARY IGNITION

Fig. 10: Here, we see a lean density misfire on a distributor equipped engine using the raster pattern from the ignition scope side of the DSO. Notice the short spark line that is bending upward with an excess amount of turbulence on #6 cylinder.

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2001 CHEVY EXPRESS VAN (LOSS OF SECONDARY)

Fig. 11: An example of a secondary parade pattern from an Express Van. Note, the missing points of primary turn-on. The PCM uses the DREF or RPM signal to determine when to turn on and charge a coil and when to turn off and fire the coil.

2001 EXPRESS VAN (LOSS OF CKP SIGNAL)

Fig. 12: Referring to Figure 11, we would suspect a faulty CKP signal as indicated here. These systems are known to have mechanical interference between the tip of the crank sensor and the reluctor wheel, creating a miss trigger, which might be caused by worn main bearings. GM offers a crank sensor shim to regain the correct air gap.

2004 MUSTANG 3.8L #5 SECONDARY

Fig. 13: An open in the secondary circuit can easily be seen by scoping secondary. Note the split firing line with no sparkline. This can be caused by an open plug wire or an open spark plug resistor.

CHRYSLER COP (PRI./SEC.)

Fig. 14: This is a dual trace example from a Chrysler COP system. On channel 1, we’re using the COP wand on top of the COP that indicates the coil’s secondary side. On channel 2, we’re back-probing the negative coil terminal (primary side). Note, the healthy 1.9 millisecond spark duration matched between primary and secondary.

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WAV E F O R M

crank sensor and the reluctor wheel creating a miss trigger. This is caused by worn main bearings. GM is aware of this problem and actually supplies a shim to reestablish the air gap. A visual inspection of the crank sensor indicated no mechanical interference. We simply ran a redundant signal lead between the CKP sensor and the PCM to confirm the signal drop out was a circuit problem. We could have also used a DSO and done the same test. We would simply use two channels. Channel 1 using a universal KV probe around the coil wire with channel 2 using another KV probe around the #1 spark plug lead. Remember to use the invert function since secondary firing events are negative firing events. An open in the secondary circuit can be easily seen by scoping secondary. Look at Figure 13. Notice the split firing line with no sparkline. This can be caused by an open plug wire or an open spark plug resistor. An ohmmeter check of the secondary lead confirmed an open. On the Ford and Chrysler, COP systems access to the primary side of the coil is a good option. We simply use the DSO single channel and back probe the negative terminal of the coil. A 1 millisecond time base at 10 volts per division is often good settings when viewing the primary side of the coil. The spark duration periods of the secondary side of the coil will be mirrored on the primary side. Let’s take a look at Figure 14. This is a dual trace example from a Chrysler COP system. On Channel 1, we are using the COP wand on top of the COP that indicates the secondary side of the coil. Channel 2 in back probing the negative terminal of the coil that indicates the primary side of the coil. Notice the time base is set at 1 millisecond per division. Notice the healthy 1.9 milli-second spark duration period perfectly matched between primary and secondary. The primary ignition drivers on Ford and Chrysler systems are inside the PCM. On late model Chrysler engines equipped with COP units, the PCM simply times the rate of the collapsing magnetic field from each firing event. This is meant to represent the spark duration period. The data is relevant and not nearly 100% accurate. Take a look at Figure 15. The #1 cylinder shows a value of just more than 1 millisecond. The other cylin-

CHRYSLER COP SYSTEM SPARK DURATION PERIOD FROM SCAN CATA

Fig. 15: The #1 cylinder on this Chrysler COP shows a value of just more than 1 millisecond. The other cylinders show a much longer value.

FORD GOOD SPARK DURATION PERIODS @ IDLE

Fig. 16: A scan tool capture of a Ford with COP. During idle/no-load conditions, uniform spark duration periods are seen on all cylinders. In this capture, the PCM is adding all three spark duration periods together.

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ders show a much longer value. The late model Ford systems equipped with COP units will also have scan data relative to firing events that can be suspect. This data should be considered relative, as well. Take a look at Figure 16. In this scan tool capture during idle/no-load conditions indicate uniform spark duration periods on all cylinders. Since the coil drivers are inside the PCM, the PCM simply times the period of the collapsing magnetic field. In this example, captured at idle, the PCM is adding all three spark duration periods together. In Figure 17, the Ford PCM reverts back to a single firing event above 1,000 RPM. Ford also gives a scan tool parameter known as acceleration PIDS (on-board diagnostic parameter IDs) as seen in Figure 18. Note, cylinder #4 indicates a crank speed slow down. The distance between the crank sensor signals are known as numerator values. When a misfire occurs, the crank speed will slow down. The problem on #4 cylinder could be a bad spark plug, or bad coil or a lean density misfire. It does not pin-point the cause of the misfire. I know in the real world with a single misfire we simply use a spark tester to verify whether or not that the coil fired. Instead by using a DSO with a secondary KV probe or a COP wand and viewing the secondary event, will not only verify whether the coil fired or not, but the misfire might be caused by a lean density misfire, a richdensity misfire, a low compression problem or an open in the secondary circuit. In your journey down the diagnostic road, I hope this information helps you, and I thank you for your commitment to this resilient industry. Bill Fulton is the author of Mitchell 1’s Advanced Engine Performance Diagnostics and Advanced Engine Diagnostics manuals. He is also the author of several lab scope and drivability manuals such as Ford, Toyota, GM and Chrysler OBD I and OBD II systems, fuel system testing, and many other training manuals in addition to his own 101 Lab Scope Testing Tips. He is a certified Master Technician with more than 30 years of training and R&D experience. He was rated in the top three nationally on Motor Service magazine’s Top Technical Trainer Award and has instructed for Mitchell 1, Precision Tune, OTC, O’Reilly Auto Parts, BWD, JD Byrider, Snap-on Vetronix and Standard Ignition programs. You may have also seen Fulton in many Lightning Bolt Training videos and DVDs and read his articles in many auto service magazines. He owns and operates Ohio Automotive Technology, which is an automotive repair and research development center.

FORD OFF IDLE SPARK DURATION PIDS

Fig. 17: On the same Ford COP system, the PCM reverts back to a single firing event above 1,000 RPM.

FORD CYLINDER ACCELERATION PIDS

Fig. 18: Ford gives a scan tool parameter known as acceleration PIDS. Note, cylinder #4 indicates a crank speed slowdown. When a misfire occurs, the crank speed will slow down.

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Benefits of Using a 5-Gas Analyzer A handy addition to your scan tool

UR JOB AS AUTOMOTIVE TECHNI-

CIANS is to repair vehicles as quick-

ly and accurately as possible. There isn’t a set way of diagnosing a vehicle as long as you repair the vehicle and the problem that it came in for. Working on today’s high tech vehicles is like going to war. While at war you want to slay your opponent by any means possible before they slay you. So choosing the most efficient and accurate weapon will go a long way in winning the battle. The same goes for diagnosing vehicles that have any type of drivability concerns. The most common weapon of choice used on the modern automobile is the scan tool. That tool will give you the most information in the least amount of time. Along with the scan tool there are various other pieces that diagnostic equipment that will aid in your diagnosis... for example, the thermal imager,

the infrared thermometer, the pulse sensor, and even the pressure transducer. Also along with those addons a digital volt-ohm meter and lab scope are sometimes necessary in completing an accurate diagnosis. In addition there are more tools that you can use to fight your diagnostic battle. One tool that has been around that many technicians haven’t thought about using is the five gas analyzer. The first thought that comes to mind from many technicians is the fact that they think a five gas analyzer is only used for emission testing. There are a lot of states that don’t perform emission testing, so the chances are those shops don’t use a five gas analyzer. Using a five gas analyzer for just emission testing is only one part of the equation, and a small part at that. Understanding how a five gas analyzer works and utilizing it to its fullest potential can be just as valuable as a scan tool. The gas analyzer has been around for many years. In

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BY EDWIN HA ZZ ARD

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safely and accurately diagnose vehicles. So let’s take a look at what the five-gas analyzer really is. The five gas analyzer is a device that measures the content of the exhaust byproduct after a combustion event. This is done by inserting a probe or more commonly known as a detector into the vehicle’s tailpipe. Once the de-

tector is installed there are sensors built into the probe that are used to measure different gases in the exhaust mixture. An Infrared light is directed through the sample gas in the sample chamber and the amount of light passing through the sample is measured by the detector. There are normally three detectors used

Fig. 1

Autodiagnos™ Pro Automotive Diagnostic System Technician-friendly scan tool that increases productivity.

the beginning it was a stationary tool that was pretty large and cumbersome to move around the shop (kind of like the old big box oscilloscopes). Fast forward to present time and now gas analyzers are available that can fit in the palm of your hand. They’re more versatile to use and can even be taken on a road test. (Fig 1) Just like new technology in the automobile that has evolved over the years, five gas analyzers have evolved as well. In this article I’m going to show you what a five gas analyzer can do to help you in your diagnostics. Remember, this is just another tool that you can use to

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Fig. 1: Here’s an example of a hand-held 5-gas analyzer. In addition to the use of a scan tool, a 5-gas analyzer can aid in diagnosing a number of issues, and are not relegated to emissions testing alone.

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WHAT IS INFRA RED MEASUREMENT? Infra red light is directed through the sample gas in the sample chamber and the amount of light passing through the sample is measured by the detector — 3 detectors used for HHGA5C • Carbon Monoxide (CO) 0-5% • Carbon Dioxide (CO2) 0-15% • Hydrocarbons (HC) 0-2000ppm Industry standard Accurate Fast Replacement not usually required

GAS IN

GAS OUT DETECTOR

IR LAMP

OPTICAL FILTER

Fig. 2

for a five gas measurement. The exhaust gas stream goes into the inlet part of the detector and then an infrared light beam is shot through the gas sample which is bounced off of and optic fi lter. Then the gas sample will exit the detector. The three gases that the detector focuses on are carbon monoxide, carbon dioxide and hydrocarbons. (Fig 2) Nitrous Oxide or NOx and Oxygen O2 are also tested as well. The deadliest or most harmful of the five gases is Carbon Monoxide or CO. A major component of polluted air, CO is a colorless, odorless gas which, when concentrated, is toxic. Any fueled engine properly adjusted and in good operating condition produces relatively low CO readings. Excessive CO develops when the combustion chamber is receiving a large volume of fuel and a proportionately small amount of air. By weight, carbon monoxide

Fig. 2: This image depicts how a diffuser on a 5-gas analyzer works. Infrared light is directed through the sample gas and the amount of light passing through the sample is measured by the detector.

accounts for about 47% of air pollution produced by vehicle emissions. Think about a cylinder misfi ring that has lost its spark, and all that extra unburned fuel exiting out the cylinder into the catalytic convertor then out the tailpipe. Does a flashing check engine light signaling a catalytic convertor damage warning come to mind? The CO reading on your analyzer will be extremely high. (Fig 3) Normal CO readings will be 0.5% or less. A five gas analyzer will catch a CO problem before it gets too bad. It may or may not see the problem before your scan tool will. This is just one example of the benefits a five gas analyzer will have in your diagnostic testing. But why test the engine for how clean it’s running? Have you ever seen pictures of the skyline over Beijing China? That haze you saw is smog. There was a great concern of having the Olympics there because of that. So what actually is smog? Smog was found to be the result of a chemical reaction that occurs in sunlight between hydrocarbons (HC) and oxides of nitrogen (NOx ). Once the government understood the contribution of vehicle emissions to air pollution, it formulated legislation to control it and that’s why we have strict vehicle emissions standards today. Let’s take a look at the comparisons of a rich and lean running engine from a five gas analyzer and compare it to the scan tool readings. Notice the CO reading on the analyzer is showing an abnormally high reading. (again, see Fig 3) The system is showing a rich condition. The Oxygen sensor reading from the scan tool is showing a high voltage reading indicating a rich condition. This was done by injecting a propane sample into the intake system to see the reaction of both the five gas analyzer and the scan tool. The scan tool picked up the rich fuel sample before the five gas did due to the location of the oxygen sensors located upstream from the five gases probe that is located in the tailpipe. It usually takes a few seconds for the enriched sample to reach the five gas probe. This is normal, due to the distance the sample has to travel. Notice the Lambda reading on the analyzer. It is showing a reading of 903. Lambda is an indicator of the air fuel mixture in the engine. A perfect Lambda reading is at one. Anything less than one indicates there is more fuel in the mixture than there is oxygen. Anything higher than one indicates there is more air than

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Fig. 3: Here’s a comparison of a rich mixture on the gas analyzer to a rich oxygen sensor reading on the scan tool. Notice the high CO and HC readings on the gas analyzer after the oxygen sensor reacted to the added propane. Fig. 4: This image shows the comparison of a lean mixture on the gas analyzer to a lean oxygen sensor reading on the scan tool. Notice the low CO and HC readings on the gas analyzer after a vacuum leak was created after the oxygen sensor reaction.

Fig. 3

Fig. 4

fuel in the mixture. Notice the high CO reading and the lower Lambda reading. That’s a sure indication of a rich running condition. Figure four is showing us the opposite. (Fig 4) The engine is now showing a lean condition which was induced by removing a manifold vacuum line at the intake manifold. Notice our CO has dropped significantly and our Lambda is now above one. The vehicle’s oxygen sensor is now reading a low voltage as well. The vehicle’s oxygen sensors are also proving that the computer system is controlling the fuel mixture as well. Notice in both different scenarios the CO2 or carbon dioxide is a little low. The spec for CO2 is 14-15%. Anything less than that is telling us the engine is showing us that the engine is not running as efficiently as it is supposed to be. This is

where a five gas analyzer will shine and a scan tool will not. The scan tool did not show any codes for these two different gas readings. My guess over time once the vehicle’s fuel trims started to change drastically they would have. The point I’m trying to make is the gas analyzer will pick up the overall efficiency of the engine after the combustion event where the vehicle’s computer might not catch the problem as it’s happening. This could be due to a biased sensor, and intermittently reading sensor or a computer software problem. Remember, I want to stress that the five gas analyzer is in no means used to replace the scan tool but another way of diagnosing drivability problems. Each tool compliments the other. The Hydro Carbon or HC is showing that it was reading high in our rich running reading. That is telling us that the cylinder(s) are not generating a complete combustion of the gases. HC is measured in PPM or parts per million. A normal reading is 100ppm or less. Anything over that is indicating a cylinder is experiencing a lack of ignition and excessive unburned fuel. Our reading of 180ppm was showing us just that. What makes the use of using a five gas analyzer is taking all the readings and comparing them to what is normal and what is not. You can see by doing that you will be able to determine what is wrong with the engine and how far off that engine actually is compared to a known good reading. I tell all my technician friends and students that whatever tool you are using, the best way to understand them is to test a vehicle that is known good. If you don’t know what known good is how are you going to know what known bad is telling you? The five gas analyzer can be used to not only test at the tail pipe but it can be used for other tests as well. For example, we know that when an engine’s head gasket might have failed or is about to fail that the engine will induce CO2 into the coolant system. Sure, we have block testers that we can use or balloon JUNE 2021 | ASP

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tests on the coolant reservoirs but how about using the exhaust probe of our five gas analyzer to test for CO2 in the cooling system? The best way to do this is remove the radiator cap or coolant reservoir cap. Do not insert the probes end directly into the coolant, as that is a sure fire way to need a new replacement tip for your gas analyzer. Make sure the coolant level is lower than the top of the tank you are testing, as if it’s a big leak you don’t want the coolant to come into contact with your probe as the engine starts to warm up. Hold the probe above the coolant level and watch the analyzer, specifically your CO2 reading. If the CO2 reading is high then more than likely your head gasket has failed. Other uses for the five gas analyzer would be to check the exhaust system for leaks by running the probe around all the connections and along the pipes for any sign of abnormal CO2 readings. Using the analyzer to check for fuel leaks is a great way of finding those pesky fuel leaks that sometimes you can’t see but can smell. Another great use of the gas analyzer is to check the integrity of the catalytic convertor. If exhaust emission test results exceed manufacturer specifications and HC cannot be adjusted to within limits, the problem could be an inoperative catalytic converter Ensure the vehicle has no ignition problems, vacuum leaks or fuel restrictions. On vehicles with feedback control, disconnect the O2 sensor to prevent it from correcting during this test. Disable the air injection system. Richen fuel mixture until CO is about 2% using propane. With mixture still enriched, enable the air injection system. Note HC, CO and O2 readings. O2 increases and HC and CO decrease significantly when air injection system is enabled when the catalytic converter is working. O2 increases and CO and HC readings do not change significantly when air injection system is enabled when the catalytic converter is not working. If O2 is higher than CO, and CO is higher than 0.5%, the catalytic converter is not functioning (not converting CO to CO2). If O2 is lower than CO, the exhaust sample is rich and the converter is oxygen starved, not oxidizing HC and CO. After correcting a rich condition the converter should begin to function again. It may take several miles of normal driving, or engine operating at a fast idle speed for about 15 minutes, before this happens. Remember, catalytic convertors are expen-

Fig. 5: Here we see a catalytic converter that has failed due to excessive CO due to unburned fuel.

Fig. 5

When diagnosing a vehicle it is important to use all the resources you can obtain.”

sive and keeping the vehicle maintained is the best practice in preventing a catalytic convertor failure. (Fig 5) Finally, another use of the gas analyzer is the separate testing of NOx on a diesel engine. With today’s after-treatment systems, testing the diesel particulate filter for efficiency based on the SCR catalyst’s performance is vital in diesel emissions testing. I will talk more on that in a future article. As you can see, using a five gas analyzer is not just for emission standards testing but it can open up a whole new avenue for your ability to perform drivability diagnostics. When diagnosing a vehicle it is important to use all the resources you can obtain. This article has only touched on a small portion of what a five gas analyzer can do. Efficiency is key to an accurate diagnosis. With the proper training and the use of quality tools then you too will have success repairing vehicles in your bay. Using a five gas analyzer in your diagnosis can be…well a gas! Edwin Hazzard owns South East Mobile Tech in Charleston, S.C., which is a mobile diagnostic and programming service providing technical service to many automotive and body repair shops. He has 38 years of experience in the automotive industry. He currently is an automotive trainer, a board member of TST (Technician Service Training), a member of the MDG (Mobile Diagnostic Group), a member of the Professional Tool and Equipment advisory board for Pten magazine, a committee member of Nastaf and is a beta tester for multiple tool makers.

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E S IM

Chrysler ESIM Understanding this system, and testing tips BY JAKE SORENSEN

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E S IM

BASIC “NON-ENHANCED” EVAP SYSTEM VENT TO ATMOSPHERE (NO VALVE)

PURGE VALVE CLOSED INTAKE MANIFOLD

CHARCOAL CANISTER

FUEL CAP

FUEL TANK

T CAN BE OVERWHELMING TO keep up with the many different methods auto manufacturers use to detect EVAP system leaks. It seems like every time I really start to understand one of these EVAP systems, the manufacturer completely changes it. While manufacturers may use the same system for several years, if you work on every make and model you will see different systems every day. Keeping up and keeping them all straight is a challenge. Hopefully you can stash this article in your toolbox and review it the next time a Chrysler ESIM (evaporative system integrity monitor) system comes into your bay. Chrysler has used relatively few EVAP leak detection methods. Starting in 1996 with OBDII, Chrysler used a Leak Detection Pump or LDP. These were different from most system leak test strategies as they used pressure instead of vacuum. The pump was not something most of us think of when we hear the word pump. They used a solenoid to pulse manifold vacuum to one side of a diaphragm. On the other side of the diaphragm were two check valves, one allowing air into a chamber but not out and the other allowing the air out to the EVAP system which was then pressurized.

Fig. 1: Early EVAP systems are now referred to as “nonenhanced;” this is to say they have no leak detection capabilities.

Starting in 2002 Chrysler switched to an NVLD or Natural Vacuum Leak Detection. The change was made in an attempt to reduce the number of parts used and simplify operation. The NVLD systems were normally sealed with a solenoid that would allow the system to vent when controlled. They also contained pressure and vacuum relief valves that opened at very low pressures. Inside this unit was a switch that made contact when vacuum was present in the system allowing the PCM to detect leaks. Then, again in an effort to reduce the number of parts and simplify operation, in 2007, Chrysler switched to an Evaporative System Integrity Monitor or ESIM which is still being used today. If you work on Chryslers, you have likely come across these ESIM systems. After all, they have been around for more than 14 years. When it comes time to diagnose an EVAP system leak or other EVAP monitoring fault, you will need to understand the ESIM operation. When referring to the description and operation in service information, you might think you are working on a spaceship. It almost seems like the intent of the author was to confuse you, not help you. Over the years, I have been asked by many technicians to help them with diagnosing failures in these systems.

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ADVERTORIAL

ler has relied on some form of natural vacuum leak detection for several decades. The Chrysler ESIM is essentially a switch that closes when the vacuum in the tank exceeds a specific pressure (typically 1” H2O). Imagine the vehicle moving around and fuel sloshing around or sitting in the sun all day; after the vehicle is parked and the fuel begins to cool down, if the tank and the EVAP system are sealed, a vacuum should be drawn on the system. At this point the contacts in the ESIM will close and report back to the PCM that the system is sealed.

EVAP Components and Chrysler ESIM Systems Take a closer look at challenging components

BEST PRACTICES FOR WORKING ON CHRYSLER ESIM SYSTEMS Chrysler Evaporative System Integrity Monitors (ESIM) have been used since the late 2000s, but due to their unique characteristics they may provide some diagnostic challenges for technicians. Whereas many manufacturers rely on some form of a purge and seal/ vacuum decay for their EVAP system self-tests, Chrys-

HOW THE ESIM WORKS The PCM uses the ESIM in several conditions. First, when the vehicle is running, the EVAP system is pressurized due to natural vapor pressure. If the EVAP system is sealed, the pressure overcomes the spring tension in the diaphragm to close the contacts in the switch. When the switch closes, the PCM recognizes that the system is sealed and then passes the test. Second, when the engine is shut off after running at operating temperature, the PCM performs a small leak test. As the engine cools, the EVAP system builds vacuum. The vacuum overcomes the spring tension in the diaphragm to close the contacts in the switch. In this condition, the PCM also recognizes that the system is sealed and passes the test. If the PCM doesn’t recognize the voltage change from the switch at the appropriate conditions, it will set one of several DTCs. Standard® offers more than 1,400 EVAP components for import and domestic applications. Standard® engineers improve on OE flaws to deliver better performing, longer lasting EVAP components and all Standard® EVAP parts are rigorously tested to ensure flawless operation. In addition to ESIM, the Standard® EVAP line includes canister purge valves, canister vent valves, fuel vapor canisters, canister vent solenoids, canister purge solenoids, leak detection pumps and more! To learn more visit StandardEVAP.com and check out our EVAP Playlist on YouTube!

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E S IM

BASIC “NON-ENHANCED” EVAP SYSTEM DURING CANISTER PURGE VENT TO ATMOSPHERE (NO VALVE)

PURGE VALVE OPEN INTAKE MANIFOLD

CHARCOAL CANISTER

FUEL TANK Fig. 2: Early “non-enhanced” EVAP system during purge operation.

Fig. 3: ESIM case or housing.

Fig. 4: Vacuum operated contact switch

FUEL CAP

When I ask them if they understand the operation of the ESIM, it becomes apparent that they do not. Some almost believe the ESIM is a small plastic box containing magical parts and top secret advanced level technology. But, at a cost of around $20, how sophisticated or complex can these really be? After looking inside an ESIM then reviewing the description and operation, we can start to understand just how simple this little component really is. Let’s take a look.

BASICS OF EVAP SYSTEM OPERATION First, it might be helpful to quickly review how an EVAP system functions and what the purpose of the ESIM is. Looking back at early EVAP systems operation helps me to understand modern systems. The goal of all EVAP systems is to prevent Hydrocarbons (HCs) from being released into the atmosphere. The problem is we can’t just seal off the fuel tank. We have all seen a gas can expand on a hot day or suck in when cold. Also, since we are going to be pulling fuel from the tank into the engine, air will need to be let in to displace it. Early EVAP systems are now referred to as “nonenhanced;” this is to say they have no leak detection capabilities. If there is a fault in the system, for example, a broken charcoal canister or split hose, the driver will likely never know or have any reason (i.e. check engine light) to have the system repaired. These systems had a hose from the sealed fuel tank that connected to the charcoal canister. Fresh air was allowed in through the charcoal canister when fuel was being consumed or when fuel temperature dropped in order to avoid negative pressure (vacuum) in the fuel tank. When filling the fuel tank or when fuel tank temperature increased, the vapors in the tank were allowed to escape through the charcoal canister which would “trap” the HCs. (See Figure 1) Then, a hose connected to a purge valve leading to the intake manifold would allow manifold vacuum to pull fresh air through the charcoal canister along with the stored HCs into the engine to be burned. This prevented HCs from being released into the atmosphere. (See Figure 2) Many carbureted models used valving inside the carburetor opposed to a purge valve. The next iteration of EVAP systems are referred to as “enhanced systems.” This means they have some sort of leak detection capabilities.

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Fig. 5: Vacuum diaphragm used to operate the contact switch. Fig. 6: Left: Small weighted vacuum valve Right: Large weighted pressure valve. Fig. 5

Fig. 6

MOVING FORWARD TO CHRYSLER’S ESIM SYSTEMS These EVAP systems still function the same way as their predecessors. They still use a charcoal canister to contain or trap HCs, and a purge valve to allow those HCs into the intake manifold when ready. The difference is in the leak detection methods … that is the whole purpose of these ESIM assemblies ... to detect EVAP system leaks. First, let’s look at what is inside these ESIM assemblies. Then, how Chrysler uses them to determine leaks. Finally, we can review some common faults you may see and how to test for them.

CHRYSLER ESIM PARTS AND OPERATION So what’s inside the ESIM? Take a look at these pictures, you might be surprised to see there are really only 5 parts that make up this unit. 1. The case or housing (See Figure 3) 2. A vacuum operated contact switch (See Figure 4)

3. The diaphragm used to seal and control the contact switch (See Figure 5) 4. Small weighted vacuum valve (See Figure 6) 5. Large weighted pressure valve (See Figure 6) The ESIM EVAP systems are normally sealed. Both the large and the small valves are weighted and held in the closed position by gravity. Because of this, it is very important that these units be installed in the upright position. The ESIM is installed on the charcoal canister along the path to the fresh air vent. It can be thought of somewhat like a vent valve. When the vehicle is being fueled or when fuel temperature rises, pressure in the fuel tank builds and vapor needs to be vented. The vapor is allowed through the charcoal canister trapping HC’s, then on to the ESIM. The large valve in the ESIM becomes unseated at about .5 inches of water allowing the pressure to vent through a filter to the atmosphere. Negative pressure is present in the fuel tank and EVAP system when fuel is being drawn into the engine, when fuel temperature drops or during purge operation. If this negative pressure reaches 2.2 inches of water, the small valve is lifted from it’s seat allowing air in through the fresh air filter. (See Figure 7)

ESIM LEAK DETECTION Pretty simple so far right? The whole purpose of the ESIM is to determine when an EVAP system leak is present. As we have seen in the images of the ESIM, there is a vacuum diaphragm and a simple contact switch. When the vacuum in the EVAP system reaches roughly 1 inch of water, the diaphragm is pulled causing the contacts on the switch to make a connection. Chrysler determines leaks using two different strategies:

FIRST: NON INTRUSIVE LEAK TESTING This takes place when the engine is shut OFF. Yes, that is correct, after the engine is shut off and the fuel tank has been naturally pulled into a vacuum. This is caused by cooling of the fuel or diurnal (normal daily) ambient temperature changes. This can only happen if the fuel tank and EVAP system are sealed explaining why the ESIM is normally closed. When this natural vacuum reaches roughly 1 inch of water, the switch inside the ESIM closes and a signal is sent to the PCM. If the switch closes in a predetermined amount of time and this occurs during a predetermined number

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of key off cycles, it is determined that the EVAP system is sealed and the non-intrusive test is passed. If the switch does not close as described, then the test is considered inconclusive and the intrusive test will be run on the next key cycle that certain criteria are met (outlined next). This does not mean a DTC indicating an EVAP leak will set, this is the start of more testing to determine a fault.

SECOND: INTRUSIVE LEAK TESTING Before this test is performed certain criteria must be met: • The engine coolant temperature must be within 50 degrees F (10 degrees C) of ambient temperature to indicate a cold start. • The fuel level must be between 12% and 88%. • The engine must be in closed loop status. • Manifold vacuum must be greater than a minimum specified value. • Ambient temperature must be between 39 degrees F and 98 degrees F (4 degrees C and 37 degrees C). • The elevation level must be below 8,500 feet (2,591 meters). Once these conditions are met, the PCM will activate the purge valve to create a vacuum in the EVAP system. The PCM then measures the time it takes for the vacuum to dissipate. This is referred to as the decay method. For example, if the switch opens quickly after the purge valve is closed, a large leak is recorded. If the switch closes after a predetermined amount of time, testing of a small leak will continue. If the small leak test continues to fail a predetermined number of times, a small leak code will be set.

Fig. 7: Cutout diagram of ESIM 1: The case or housing 2: A vacuum operated contact switch 3: The diaphragm used to seal and control the contact switch 4: Small weighted vacuum valve 5: Large weighted pressure valve

Fig. 7

OTHER EVAP SYSTEM FAULT TESTS These intrusive and non-intrusive tests are performed to determine leaks in the EVAP system. The PCM still needs to test or to verify there are no faults in the system operation. To do this, Chrysler uses two additional tests, the purge monitor test and the ESIM switch stuck closed monitor. Here’s how those two tests operate:

PURGE MONITOR TEST This test is performed to verify the purge valve is functioning and will only be run if the small leak test has passed. Since the small leak test has passed, we JUNE 2021 | ASP

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know the purge valve is capable of sealing the EVAP system from the intake manifold. We don’t know if the purge valve is opening or if a good manifold vacuum is present. You may have noticed some of these vehicles using an ESIM have a fuel tank pressure sensor (FTPS) and others do not. The FTPS was added in 2012 on most models and is used ONLY for the purge monitor test, it is NOT used for any leak testing.

NO FUEL TANK PRESSURE SENSOR 2007- 2011

Fig. 8: Voltmeter connected to two wires (backprobed) of the ESIM with no pressure or vacuum in the EVAP system, reads 4.6v.

The Purge monitor test is performed in two stages. The first stage monitors the vapor ratio during normal EVAP purge operation. The vapor ratio is a calculation made by the PCM by monitoring the short-term fuel trims during purge operation. If short-term fuel trims do not react as expected, the stage two purge monitor test will take place. For the stage two test, the PCM operates the purge valve more aggressively. If the vapor ratio does not respond, a code P0441 is set indicating a purge flow fault.

FUEL TANK PRESSURE SENSOR AROUND 2012 AND NEWER

Fig. 9: Voltmeter connected to two wires (backprobed) of the ESIM with a scan tool controlling the purge valve open, voltage reads 0v.

Vehicles with a FTPS perform the purge monitor test in two stages, as well. First stage monitors the fuel tank pressure during normal EVAP purge conditions. If pressure changes in the EVAP system and are not as expected during purge operation, the second stage test will be performed. For this test, the PCM increases and decreases the purge valve in a more controlled or deliberate manner, while monitoring the FTPS for the expected changes of pressure in the system. If pressure in the EVAP system does not change as expected, a code P0441 is set.

ESIM SWITCH STUCK CLOSED MONITOR The final part of this system that the PCM needs to test is the vacuum switch in the ESIM. This is done at key off, engine off. The PCM energizes the purge valve for up to 30 seconds, this will vent any vacuum that may be present in the EVAP system. If the switch is already open or opens when this test is performed, the test passes. If the switch was closed and stays closed, a fault is recorded and a code P0452 set.

FAULTS AND TROUBLE CODES Fig. 10: Testing resistance of the ESIM switch with vacuum applied and switch closed, reads .5 ohms.

Now that you have a better understanding of how these systems work, we can look at what faults you may en-

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Fig. 11: Since there is no longer an EVAP service port, you can connect the smoke machine at the ESIM fresh air vent. This also eliminates the need to block off the vent path to seal the system. Smoke machine connected to ESIM vent, to perform leak testing.

counter and how to diagnose the cause. As you know, there are many trouble codes that can be set on today’s complex vehicles. It would not be practical to list each of them here. Also, I do not believe it is good practice to memorize things that can easily be referenced in service information. Most of the trouble codes relating to this system fall under one of only a few categories. Here is a list of those common categories along with a short testing plan and the likely fault code: Note: Tests are listed in this order since later tests will include performing tests listed earlier. They are not listed in order of most common.

ESIM SWITCH FAULT (P0452) The ESIM switch has two wires, a 5v reference from the PCM (usually about 4.5v actual) and a ground supply. Here’s how to test its operation: 1. With no vacuum in the EVAP system a voltmeter should show 4.5-5v when connected by back prob-

Fig. 12: Various sizes of vacuum hose, used to make an adapter to connect a smoke machine to the ESIM vent.

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E S IM

EVAP SYSTEM LEAK (P0456 SMALL LEAK, P0455 LARGE LEAK)

Fig. 13: New ESIM

ing the two pins. (Figure 8) • If not, you have a circuit fault. Determine if you are missing the PCM supplied 5v or the ground path. 2. Now apply a vacuum to the EVAP system by using the purge valve controlled with a scan tool. You should see the voltage drop to near 0, if not, replace the ESIM. (Figure 9) • If the switch does not close you will want to verify the purge valve did open and there are no leaks in the EVAP system. After all, if the system was not pulled into a vacuum of more than 1 inch of water, the switch should not close. 3. If the switch does operate as it should, disconnect the two wire connectors and connect an ohm meter directly to the ESIM switch terminals. • Now test the resistance with the switch closed. It should have low resistance (around .5 — 2 ohms). If you find high resistance (over about 2 ohms), replace the ESIM. (Figure 10) In my experience, most scan tools will not allow you to monitor the ESIM switch PID while controlling the purge valve (real convenient). Also, I have found most scan tools to display only a value of open or closed, not a voltage reading. Meaning you cannot monitor bias voltage in place of using a voltmeter.

Before any testing, make sure there are no fault codes stored that could cause the leak test monitor to be inaccurate. Such as the P0452 code indicating an ESIM switch fault. Then follow this test plan: 1. I always start any EVAP system leak fault testing with a visual inspection of the system. Many times you will find something obvious like a damaged part, torn hose or missing gas cap. 2. You will now need to perform a system leak test. Here’s the method I prefer: • Disconnect the fresh air vent hose from the ESIM and connect the smoke machine in its place. You may need to make an adapter using various sizes of hose as seen in the image. Since you have installed the smoke machine on the vent path the system should now be sealed, and you did not need to disrupt any fittings or valves. (Figures 11 and 12) • You can now turn on the smoke machine and monitor for leaks being sure not to use excessive pressure. 3. If you did not find any leaks, you will now want to test the ESIM switch operation as described for the ESIM switch fault code (P0452). 4. Verify the ESIM vent filter is not restricted. It should allow air to flow freely. 5. You have now tested all possible causes excluding the valves in the ESIM. You can remove the ESIM and connect a vacuum / pressure pump along with a gauge to test the valves for sealing OR I prefer to replace the ESIM at this point. You can call it the process of elimination diagnostics. Since we have tested all other causes, this has to be our failure. Note: a small leak code (P0456) will only be set after a large / medium leak test is performed.

GAS CAP LOOSE / GROSS LEAK (P0457)

This fault is monitored and tested the same as a large system leak; however, the PCM also noted a large change in fuel level. Perform testing the same as other EVAP system leak faults. You may want to start by testing the gas cap if you have the equipment (many emissions testing stations). During smoke testing, pay close attention to the gas cap.

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Fig. 14

Fig. 15

PURGE SYSTEM PERFORMANCE (P0441) Perform testing for any leak faults or ESIM switch fault codes first if also stored. On vehicles with a fuel tank pressure sensor monitor the sensor value on a scan tool while controlling the purge valve on. On those without a fuel tank pressure sensor (2007 - ~2012), connect a vacuum gauge in place of the fresh air vent on the ESIM. You should see pressure drop steadily to manifold vacuum. If not: 1. Verify the purge valve opened and the circuit was energized. 2. Verify there is good manifold vacuum present to the purge valve. 3. Test the ESIM fresh air vent for restriction. It should flow air freely. 4. Test the hoses from the purge valve to the fuel tank for restriction. 5. Verify the ESIM vent filter is not restricted. It should allow air to flow freely.

GENERAL EVAP SYSTEM FAULT (P0440)

This fault will set if the ESIM switch does not close

Figs. 14 & 15: This is a common ESIM failure. When the plastic is cracked, corrosion is allowed to grow on the contacts causing high resistance. This ESIM was causing a code P0456 small EVAP system leak detected.

during the intrusive leak test. Since there are many possible causes, the PCM cannot determine what the failure is and sets a general fault code. Perform the following tests as they were described previously. 1. Start by performing a system leak test. 2. Test the operation of the ESIM switch. 3. Test the purge system performance. 4. If all the above tests pass, replace ESIM. It’s been said many times that a good technician can fix anything, if he understands how it works. Hopefully you now understand how these Chrysler ESIM systems work. Armed with this understanding and a logical testing approach, you can quickly find the problem the next time a Chrysler with an EVAP system fault comes into your bay.

Jake Sorensen is the 2019 NAPA ASE Technician of the Year and 2019 Ratchet + Wrench All-Star technician of the year. He is an ASE Master Technician with L1, L2 and L3 certifications. He is the shop manager and diagnostic technician at McNeil’s Auto Care in Sandy, Utah, where he developed the NAPA Auto Care national apprenticeship program. JUNE 2021 | ASP

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TeChnICal ServICe

bulleTInS

DODGE

LINCOLN

RAM DEF DEFECT

ROUGH IDLE AFTER HOT MKT RESTART

This bulletin applies to 2014-2015 Dodge RAM 2500 and 3500 trucks equipped with a diesel engine. The DEF level sensor might have a manufacturing defect. A MIL may be illuminated. DTCs P203B (reductant level sensor circuit performance), P203C (diesel exhaust fluid..reductant level sensor circuit low) and/or P203D (reductant level sensor circuit high) may be stored. The DEF system uses a complex radio frequency type level sensor to detect the amount of fluid present in the DEF tank. As the fluid level in the tank decreases, the level sensor becomes exposed to air which alters the signal sent out by the sensor. The sensor translates the signal change into a fluid level and busses the information to the instrument panel cluster via the dosing control unit (DCU). A manufacturing defect in the level sensor may have occurred. Replace the DEF pump assembly and ensure that the DEF tank is approximately ½ full. Using WiTECH, perform a DEF reductant doser pump prime override test a total of 10 times to ensure that the DEF pump has been sufficiently primed and that all air has been purged from the pump and filter. Turn the ignition key on and ensure the DEF level gauge is reading properly. The new module kit is available as P/N 68192659AC.

Information courtesy of Mitchell 1

fuse for the EKPS, located in the rear fuse carrier. If the fuse is found open or faulty, then check the part number of the EKPS control module. If P/N 16 14 7 447 895 or 16 14 7 450 992 is installed, then the fuse and the EKPS control module need to be replaced together. If the fuse is not faulty, work through the applicable test plan for the fault stored.

Some 2013-2014 Lincoln MKT vehicles equipped with a 3.5L GTDI engine and built before June 1, 2014, might exhibit a rough idle and/or DTC P0087 after a hot engine restart. Reprogram the PCM to the latest calibration using IDS release 90.03 and higher. Files are available at www.motorcraft.com.

CHEVROLET

BAD EXPRESS PUMP

BMW

STALLS DUE TO FUSE This bulletin applies to 2015 and later BMW 328i vehicles, 2 series, 3 series and 4 series vehicles. The engine might stall right after starting and/or the engine cannot be restarted. One of the following faults will be stored in the DME: FC 118033 (gasoline engines) or FC 2BAB00 (diesel engines). The power supply fuse for the fuel pump control electronics (EKPS) can fail due to an internal control module problem. Check the

This bulletin applies to 2012-2016 Chevy Express Cutaway vehicles equipped with a 6.0L gaseous dedicated LPG system three-tank configuration fuel system. These vehicles may experience an inoperative fuel pump leading to a no-start or stall without warning. GM has decided to conduct a voluntary emission recall involving certain vehicles. The fuel pump is to be replaced with a new design, available as P/N 23373813.

Visit autoserviceprofessional.com/TSB for additional service bulletins.

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