Originally Posted by
Romad
Haven't had the car running for about a month getting the front bumper repaired. "But" before that the car would not stay running. It would start and stumble after a few seconds and then cut off. Now, a month later air cleaner off, it starts up just fine but after a little warm up time it stumbles, or dies, until given it a little gas and get a "little" more rpm's on the engine and runs fine above idle. Symptom has changed from a month ago. Fuel delivery seems fine. I'm figuring the MAF needs cleaning as a place to start. I tried to remove the whole assembly but can't get the dad blamed thing off. The stainless steel clip at the back is cleared but seems the rubber grommets don't want to let go. I guess I'll just unscrew the MAF sensor by itself. If not the MAF sensor, and checking voltage to it, does anyone have any suggestions. Has recent cam, crankshaft sensors as well as the RCM.
UPDATE @5:15PM........Sorry I did forget to mention that I had pulled a code P0101. Mass Air Flow A circuit range/ performance.
You are not looking closely. The symptom-function troubleshooting technique demands you look at the bold text and ask yourself, "What is the ECU getting from the MAF/IAT that is thinks is wrong/out of range"?
Go look at the six codes in the list that the ECU can generate having to do with the MAF/IAT. This is the most vague one of all. But we KNOW that the data the MAF/IAT is giving the ECU is NOT being trusted by the ECU. This is a case where I might clean the MAF (I have little confidence in doing so) but I'd more likely replace it. (And if it was the IAT half, you'd have a P01xx code.)
I know I lecture people like this: "
A code from a sensor means the sensor might be bad, OR the sensor might be telling the truth and something else is actually bad causing the code, so do not change a sensor just cause the code mentions that sensor". But in this case, given your symptoms and the code, I would lean towards the MAF being bad. Unfortunately, we don't know what exactly the ECU does not like in the data coming back, but you could hook up a live data code reader and SEE what you see.
I also know that MAF codes can be a result of a Throttle body that is lying to the ECU about what position it is in, the ECU accepts the TB data and then sees too much or too little air flow and blames the MAF, based on the lies of the TB. This should NOT happen, as the TB has two data outputs, so the ECU knows if they are different, the TB is lying. But if the 5 volt feed to the TB is bad, both outputs would be off equally, fooling the ECU.
Based on the fact it smooths out at certain throttle positions, I don't think it's the crank sensor, I think it's fuel-air mix related and the ECU uses the MAF and TB, working together, to manage that ratio, but the ECU can't do that effectively if EITHER device provides bad data.
If it were MY car, unless I am missing something or ignorant about the history of the car (both possibly true), I'd order a new MAF. I mean, I'd try to clean it but if that did not work, I'd still assume the MAF is at fault. I could be wrong, but again, the clues so far imply a bad fuel/air ratio. Could the Crank sensor be a flake such that, at low speeds, the ECU can't run the engine right but can at high speeds? I do not know the answer to that question, so put in your spare BOSCH sensor and find out, since it takes ten minutes. But I bet $20 it it not the CPS.