Hi everyone,
I posted on here about this issue awhile ago but am looking for possible ways to figure out which cause is most likely or the easiest to test. Any advice would be appreciated PLEASE.

My CEL came on and I had someone read the code about 3 months ago. They said it was a P0171 reading and the 3 most likely causes are a faulty MAF or heated 02 sensor or a large vacuum leak. In addition to these, I have been told to replace the PCV system or to replace the fuel pump relay. I need help narrowing it down because I am a poor college student and am having my friend help me with the work as I know little about cars.

Here's what I have observed:

Sometimes the car will run totally fine. Other times it will stall while I am driving - when it does stall it is when I'm at a stop or just starting to accelerate. Other than the stalling there are no other problems.

The check engine light doesn't stay on, sometimes it will be on and sometimes it wont be. It does NOT seem to directly correlate to it stalling. Sometimes it will stall and the check engine light won't even be on. Weird?

I have been driving it the past 3 months and the issue has not gotten any worse. Sometimes I will drive it for up to an hour and there will be no stalling.

I did do a PCV test with a rubber glove over where you put the engine oil - the glove did blow up indicating it needs to be serviced. The problem is my friend has never done this before and is wary about doing the job (which takes about 3-6 hours since you have to take everything apart) when it might not even be the problem.

Any ideas? Most people I have told are confused since it sometimes runs fine - has anyone encountered a problem like this before? Could the PCV system make the CEL come on? Is there a way to test the MAF sensor or fuel pump relay?



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You could try to give the MAF a good cleaning with some spray cleaner made just for the purpose. Remove the sensor from the air box to do it, and make sure that the sensor is completely dry before reinstalling. Also a bad PVC system with perished rubber elbows or bad hoses could cause massive vacuum leaks downstream of the MAF sensor causing the engine to run lean. Hope this helps.

 

Thanks for the advice! Cleaning the MAF sensor seems like a simple enough task so I will be doing that as well. It seems that I should service the PCV system anyway so that will be the first thing we try.

Does anyone know any reliable locations I could get a PCV kit?

 

Fcpeuro.com Original parts, good prices.