1999 Chevy Cavalier idle going up at neutral

DOMINIC88

MEMBER
1999 CHEVROLET CAVALIER
4 CYL
FWD
MANUAL
210,000 MILES

Hi guys I just finish my mechanic class and I never heard of a problem like this.

i have a 1999 cavalier z24 2, 4l manuel with a peep flow. When I start the car there is no problem its when im on the road for about ten minute every time I shift a soon as I pass neutral the rpm goes up to about 4000 rpm and then if I put it in gear and release the clutch the rpm drops to normal. If I give it a quick shot of gas at neutral then the rpm goes back to normal

could it be my iac or my peep flow who does that. I have no mat under my pedals.

3 Replies

MMPRINCE4000

MECHANIC
8,548 POSTS

IAC could be part of problem, could also be a vacuum leak or the throttle body plate sticking.

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Sunday, August 8th, 2010 AT 8:37 AM

DOMINIC88

MEMBER
2 POSTS

So if I clean my throttle body it should be fine? If it was a vacuum problem wouldnt it be permanent?

Last night I gave a couple of quick stroke on the gas and the rpm drop down to normal it sounded like 1 backfire and it was fine after. Took the car this morning no problem everytime I shifted the rpm drop to normal while in neutral.

So just put some intake air cleaner in the throttle body while I rev it thats it?

Thnak you very much mmprince4000 for the quick answer