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GM 3800 3.8L RPMs bouncing, sometimes stalling?
2003 Chevy Impala,
as the question states, it hiccups occasionally (every 10-15 seconds or so) when idling, and when coasting at highway speeds after it's upshifted and the RPMs settle. It does it when I brake too, and in some cases has stalled when braking. Is it the MAF sensor? I hope sopmeone who's been there can answer this, since the MAF costs about $150, I'd hate to get it and then someone say "No it's not that, it's such & such..." lol, THANKS!
* @ MrKnowItAll,
No, but there had been a check engine light on for a year or two, but recently it went off when I changed my air intake to a K&N. The light never came back on. The intake has been in for a few months, but the RPM issue has only been the last 2 weeks (I doubt they're related). But no warning lights of any sort.
...and when the light was on, the code was for the O2 sensor or something similar, exactly what the user manual says is likely the problem with that light.
*Thanks Mr & Ken, appreciate the advice and the links. Mr, no I bought it used 5 yrs ago w/ 42,000. Never an engine problem until this minor episode, @ 113,000.
2 Answers
- Ken DLv 51 decade agoFavorite Answer
A real good test for the MAF is to unplug it. If the ECM does not see a MAF sig. it will use a default value, in accordance with eng temp,rpm etc. It will put your CEL, but will run fine. I doubt it is the maf. Everything it does, is slow, and stable, I would suspect the crank sensor. Give it a light tap test, see if it stalls. I can't remember if the ECM looks at the crankshaft sensor, after eng start, but I think it does, on the series 3 eng, which you have. Being the tach is jumping as well, it has something to do with the ignition system. Lots of problems with the crank shaft position sensors. My mind keeps coming back to that. Good luck.
- Mr. KnowItAllLv 71 decade ago
Is the "check engine" light on?
If so, what codes have you retrieved?
ADDED:
I've done some research and found a lot of recalls and TSB (technical service bulletins) for your car.
Too many to copy and past into my answer.
I will and the Hyperlink to the website so that you can peruse them and see if there is something the dealer failed repair/service.
http://www.automd.com/recall-tsb/search/?year=104&...
Curious..Did you buy this new?
ADDED: #2
Oh, by the way..the computer will do a quick scan of all the sensors before you start your car to see if there are any sensors "out of range".
I know on my Camaro I had issues with a random, but steady misfire.
Turned out to be those stupid metal clips over the spark plug boots were creating a short.
After removing them, all was good.
Just a thought.
ADDED: #3
The computer will not set a misfire code for brief misfires. (less than 9 seconds)
