Running Rich on Both Fuel Trims?

RALPHP1254

MEMBER
2003 OLDSMOBILE ALERO
3.4L
6 CYL
2WD
AUTOMATIC
191,800 MILES

This car is running super rich on both fuel trims. I have a screenshot of how everything is reading. We have replaced fuel injectors, the regulator, fuel pump, spark plugs and just about everything you can think of and it’s still running rich and smells bad from the exhaust. I either feel like it’s a PCM fault or a faulty sensor. Is there anything y’all would suggest looking at? The MAP is reading low as well.

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7 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,665 POSTS

Is it hot where you are? 102 degrees for the air intake? Anyway, the computer is trying to lean out the exhaust. I have seen a clogged catalytic converter cause this issue or bad fuel pressure regulator. Here is a guide to help you test the cat and I would remove the vacuum line from the regulator to see if raw fuel is present which means the regulator is bad.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

This guide can help you go over other rich conditions which you might not have thought of:

https://www.2carpros.com/articles/why-an-automotive-engine-will-run-rich

Here is the fuel pressure regulator location so you can check it out. Check out the images (below). Please upload pictures or videos in your response of any problems so we can see what to help you with.

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Saturday, November 9th, 2024 AT 11:47 AM

RALPHP1254

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It’s 65 degrees here. I just replaced the cat on it a month ago and a fuel pressure regulator was put on it a week ago. Still smells like fuel in the line when shut off. Running, you can’t smell it.

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Saturday, November 9th, 2024 AT 1:28 PM

KEN L

MASTER CERTIFIED MECHANIC
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I am thinking you have a fuel injector that is stuck open or the EGVAP purge solenoid is stuck open. How does it run at idle? Can you upload a short video? One of the spark plugs will be washed clean and that will be the cylinder that needs to be replaced. Here is the EVAP solenoid so you can see if you can blow through it which you should not be able to. Also, the air intake temperature says it is 102? So that sensor is bad or the PCM is bad. Check out the images (below). Let us know how it goes.

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Sunday, November 10th, 2024 AT 8:57 AM

RALPHP1254

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Here is a video of the idle. I can smell fuel around bank #1 around one of the injectors.

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Sunday, November 10th, 2024 AT 11:08 AM

KEN L

MASTER CERTIFIED MECHANIC
47,665 POSTS

Thanks for the video, clean car BTW, did you remove the vacuum line from the fuel pressure regulator, you might have defective part. Also, did you check the EVAP valve?