Chev / GMC misfire running rich diagnosis and replacement

http://www.wellsve.com/ This video demonstrates how to diagnose a sticky poppet injector utilizing scan tool and 5 gas techniques. The upper and lower intake are removed and replaced. The distributor cam sensor retard is re-synced using a scan tool. The re-sync also needs to be performed at times when a P0340 trouble code sets.

The information presented in this program is based on a specific diagnostic case and might not directly apply to the vehicle you are repairing. We do not represent or warrant that the information presented is complete or error free. Please take all safety precautions. We disclaim any and all liability for losses, injuries or damages in connection with your repair.

Category:

Autos & Vehicles

Tags:

• Chev
• GMC
• poppet
• injector
• 5 gas
• cam sensor
• P0340
• intake
• replacement
• diagnosis
• sticky
• running rich
• misfire
• low power
• catalytic converter
• smoke machine
• Coolant leak
• engine
• car

[nobleheight]

6:37 "Elongate the distributor mounting holes." Is that a good idea? I looked up this vehicle (97 GMC Jimmy) on ALLDATA, and ALLDATA says "NOTE: The Distributor is located in a fixed, non-adjustable position. No attempt should be made to adjust the engine base timing by rotating the distributor. Attempting to do so may result in engine cross-fire and misfire conditions. Timing is not adjustable. Ignition timing can be changed by reprogramming the PCM using TIS2000 PC, and the Tech 2 scan tool."

[Wellstech]

@nobleheight You have to remember, there are a lot of shops that don't have this equipment and can not afford to purchase it for limited use. This is an alternative method to accomplish the same result. This is a technique used my techs for many years and has proven to be successful. As long as the timing is set to zero there will be no issues.

Mark Hicks

Wells Vehicle Electronics

[Wellstech]

@nobleheight You are right it is a calculated value. Love the idea of measuring before combustion. In a round about way it is what we are doing now by measuring the amount of air coming in etc. But to measure just prior to combustion would be perfect. Never say never!

Mark Hicks

Wells Vehicle Electronics

[nobleheight]

@Wellstech It seems to me that misfires cause the 5-gas analyzer to display a false air/fuel ratio. I believe that it is a calculated value. It has to be unless you drill a hole in the combustion chamber and stick a 5-gas analyzer probe into that hole to measure pre-combustion gases (since the term air/fuel ratio describes a condition before combustion). I wonder if there will ever be a time in the future where cars have a 5-gas analyzer probe built into the combustion chamber.

[Wellstech]

@nobleheight You remind me of someone I know very very well. I have a feeling someday you will be on this end of the questions. The book is absolutely correct! Keep it up I can tell you really love what you are learning. If you have find yourself in Wisconsin I would be honored to take you on a tour of our facility. Keep reading!

Mark Hicks

Wells Vehicle Electronics

[nobleheight]

@Wellstech The book I got from the Pennsylvania Department of Transportion says ". . . This is why CO is such a good rich exhaust indicator." It also says "CO2 indicates combustion efficiency."

[Wellstech]

@nobleheight I have to agree it does appear a little lean. This shot was taken right after the job, there was no road test. Just start and take the readings. After the road test and the PCM learned the new values it came into a normal range.

Mark Hicks

Wells Vehicle Electronics

[Wellstech]

@nobleheight It is 498.1, the font they use is funny when a 3 appears it kind of covers the decimal point.

Mark Hicks

Wells Vehicle Electronics

[Wellstech]

@nobleheight This was one of the issues with early computer vehicles. If the O2 saw lots of oxygen the algorithm was to add fuel. A mistake when a misfire occurs especially a rich condition misfire. this is the main reason air/fuel ( or oxygen/fuel as you like to call them ) ratio came into being, in my opinion.

Mark Hicks

Wells Vehicle Electronics

[Wellstech]

@nobleheight Ahh Haa very good!

Mark Hicks

Wells Vehicle Electronics

[Wellstech]

@nobleheight Not true. CO is a reading of incomplete combustion, which you can and probably will have with a very lean mixture.

Mark Hicks

Wells Vehicle Electronics