Running too lean and backfiring while driving

BRIANNAAALETA

MEMBER
2007 GMC YUKON
5.3L
V8
2WD
AUTOMATIC
175,000 MILES

My SUV has had a lot of problems with the fuel delivery system. The system is running too lean, its misfiring, backfiring in the manifold, and the exhaust when you're driving. It sounds like tennis balls are popping everywhere. You give it too much gas, it cuts off. It gets no power and stalls when I start to slow down it cuts off. I changed my fuel pump and it's doing the same thing.

Sunday, June 26th, 2022 AT 12:46 PM

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
51,772 POSTS

It sounds like it could be a bad MAF sensor, if so, it will tell the computer the volume of air is way less than what is going into the engine, therefore the mixture will be lean. We should run the codes to see what comes up. here is a guide to help:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Also, the engine can be having a mechanical issue, but I can tell for sure if you please upload a short video here in your response. I would remove the spark plugs to check their condition and do a compression test to make sure the engine is okay.

https://www.2carpros.com/articles/how-to-test-engine-compression

Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

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Monday, June 27th, 2022 AT 9:45 AM

BRIANNAAALETA

MEMBER
8 POSTS

It's throwing these codes now, but I clear it every time and when I read the codes again it's always popping up something different.
P0171
P0174
C342D
P0055
Are the codes it's throwing now but these are some of the codes that have been popping up.
P0326
P0335 which is the initial code it was throwing I've changed the crankshaft, but it wasn't a brand new one.
P0068
P0102
C3064
P0068
C2174
C0361
C2520
There are numerous more that it has read just today.

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Monday, June 27th, 2022 AT 6:35 PM

KEN L

MASTER CERTIFIED MECHANIC
51,772 POSTS

How does the engine wiring look, in good shape? With this many problems and codes, it sounds like the PCM is bad. To be sure let's do a CAN scan which is the future of automotive repair you can get a CAN scanner from Amazon for about $30.00. here is a video to show you how and a link to a scanner from Amazon:

https://youtu.be/u-4syLc-ifQ

and

https://amzn.to/3OpAotj for the scanner

Also try to clear the codes, then shut the key off, then turn the key on without starting or cranking the engine over and then run the codes again to see what comes up. Check to make sure the engine and body have a good ground as well. Here is how to replace the PCM in the diagrams below.

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