Mechanics

ENGINE ROCKING AT WARM IDLE SPEED

1999 Pontiac Grand Am • 2.4L 4 cylinder FWD Automatic • 148,000 miles

When the engine is cold the idle is 1000 rpm and the engine runs fine but when it warms up it drops down to 500 rpm and the engine rocks like it has a misfire.
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DennyL12
August 16, 2014.




Clean throttle plate on both sides and iaac hole with choke cleaner then check for a vacuum leak

Hmac300
Aug 16, 2014.
I already cleaned the throttle body and replaced the IAC valve. I also checked for vaccum leaks but it still was rattling an shaking a lot to the point where I could see it but the car is not throwing any codes.
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Tiny
DennyL12
Aug 16, 2014.
Usually it will throw a misfire code if it's that bad. Check fuel pressure then do compression test

Hmac300
Aug 16, 2014.

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