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I have Regal with a non supercharged 3.8L. In cooler weather it runs like a top. When it gets above 70-75, its another story.
If I drive the car until its up to temp. shut it off (eg. go into a store) and come out to restart it, it starts up fine, but if you watch the tachometer, the idle is very unstable. If you rev it a little to get it to clear up the entire car will shake quite hard. Its obiously not running on all cylinders. The Service Engine Soon light is NOT on. As fast as it comes, it goes right away.
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when was the last time the car was tuned up? Try this power balance test to narrow down the problem.
Before any parts get bought watch the video and perform this test.C8-)http://www.youtube.com/watch?v=bAOmUjAj … plpp_video
If you live in a cold weather area that uses a winter blend gas it could be just this. If you let your tank down to 1/2 or less the gas will actually start to cause a vapor lock condition. Especially on a return system.
Try keeping your tank full and see what happens and wait for the summer blend to come out. You can also try releasing the pressure at the fuel rail and listen for air escaping just before the gas comes out. Be careful when trying this. See if car runs better after.I would check for vacuum leaks. Those engines along with the 3.1/3.4 v6’s were known for lower intake gasket failures. Here’s a video.
http://www.youtube.com/watch?v=9CPqbaSgcok
Good luck.
Quoted From Beefy:
I would check for vacuum leaks. Those engines along with the 3.1/3.4 v6’s were known for lower intake gasket failures. Here’s a video.
http://www.youtube.com/watch?v=9CPqbaSgcok
Good luck.
Shouldn’t an intake gasket leak be more prone on a cold engine and then gradually get better as the car warms up. This problem he his having is a warm weather warm start up problem. Intake gasket would be all the time but better or not as bad on a warm engine.
Check for a leaky fuel pressure regulator. Use a clear piece of tubing and attach it to the FPR. Try to keep a vacuum on it for several minutes and watch for a slug of gas coming from the FPR. A leaky FPR will not usually set any DTC on a GM engine and the hot restart problem is the beginning of this problem.
Quoted From Heath Knox:
Shouldn’t an intake gasket leak be more prone on a cold engine and then gradually get better as the car warms up. This problem he his having is a warm weather warm start up problem. Intake gasket would be all the time but better or not as bad on a warm engine.
Good call man. It was late, and I didn’t read the full post. I just read “hunting idle”. My bad. Killman has an excellent suggestion.
Here is a video that may help but i agree with testing fuel pressure. I would be testing it KOEO and seeing if the pressure holds.
It would also be interesting to see what your fuel trims are at as well as seeing what your ECT values are.
Scanner Danner leaking FPR –
http://www.youtube.com/watch?v=AKtR_yF7 … AyUMvLM%3D
I feel perhaps more evidence may be needed. I like the suggestion about checking the fuel pressure regulator as that could come into play, you might take it a step further and check the actual fuel pressure to see if it’s in spec as low fuel pressure during a hot start can cause idle issues. I also agree that if it were a vacuum leak it might show up all the time rather than just when the engine is warm. Lastly I’d suggest checking the tube that goes from the air cleaner housing to the throttle body for any air leaks, leaks here will cause the fuel mixture to be off and won’t necessarily set a code.
I was busy the last few days.
I’ll have to get a fuel pressure gauge, and I’ll check it. I’ll also check the fuel pressure regulator. Thanks
I checked the fuel pressure regulator, it doesn’t seem to be leaking, and that’s good, because for $120 bucks from NAPA, I think it would’ve had to wait.
I’ll check the fuel pressure, and take it to my Uncle, who has a really good scanner (similar to the one ScannerDanner uses) and see if its got any codes.
Even tho the CEL isn’t on, there can be stored codes, right? I’m getting 19-20mpg city, if that any of you anything!
Codes can be stored if they PCM sees a problem that takes several drive cycles to set the CEL, but they usually aren’t huge problems. The CEL is essentially there to let you know that your vehicle is doing something all the time that is making it inefficient, either fuel economy or emissions. 19mpg with a supercharged 3.8 in the city doesn’t seem horrible to me depending on your driving style.
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