Mechanics

CHEVY IDLE SURGES UP AND DOWN AND BOUNCING OI

1991 Chevrolet Cavalier

Engine Mechanical problem
1991 Chevy Cavalier 6 cyl Front Wheel Drive Manual 130000 miles

i have a 1991 cavalier has a 3.1 v6 5 speed when the car is idling it idles up and down only sometimes and when the idle drops down and then back so does the oil pressure idk changed the tps and iacand no change almost like the engine is surging also has a miss only at idle cant find a vaccum leak anywhere
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Sean_zacker
November 19, 2009.




Got to be a vacuum leak somewhere, IAC is attempting to compensate but can't because of leak.
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Mmprince4000
Nov 22, 2009.
I have checked all over I can here like a pss pss sound but might be the exaust cause its not all the way tight at the flange

Tiny
Sean_zacker
Nov 22, 2009.
You can spray carb cleaner at suspected vacuum leaks, any change in idle is where the leak is.

Mmprince4000
Nov 23, 2009.
Ok I just did that and found nothing I need help

Tiny
Sean_zacker
Nov 24, 2009.
You need a scanner that can read live data. Watch the movement of the IAC (called " steps" ).

Most shops can generate smoke that will migrate toward the vacuum leak.

You could try a compression and cooling system pressure test.

But it could also be a leaking injector seal, intake manifold gasket.

Also scan timing advance.

Mmprince4000
Nov 24, 2009.

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