Idle Problem

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Dec 16, 2006 | 01:30 PM

Doug 87L98

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Drifting

Joined: Dec 2004

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From: Doylestown PA

Idle Problem

My son has a 89 Z28 with a L98 engine.

Just yesterday his car developed an idle problem while driving. When the car is idling it starts to die and the RPMs drop to under 100, and then it surges back to normal idle RPMs and repeats in a very rythmic fashion. While under power the car seems fine. Also at start up the car seems fine. This seems to only happen while idling.

I know this is a Corvette site, but I've never encountered this problem on my 87 Vette, so I was hoping some one could point me in the right direction in diagnosing this problem. It is a Vette engine ..... right?

Thanks.

Dec 16, 2006 | 01:45 PM

_twisted_

Safety Car

Joined: Nov 2004

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From: The Pines South Jersey

check the throttle body shaft for excessive play - it could also be a lazy IAC valve

Dec 16, 2006 | 10:15 PM

Sam Lam

Melting Slicks

Joined: Apr 2002

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From: St. Charles, MO Route 66 Corvette Club

Any codes displayed when you short A&B on the ALDL? It sounds like an IAC motor problem as the car runs well under load.

Dec 17, 2006 | 06:57 AM

RRT vette

Le Mans Master

Joined: Feb 2006

Posts: 8,753

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From: Louisiana

Sounds like a vacuum leak or a dirty/lazy IAC. The IAC is located in the bottom of the throttle body. I would be leaning more toward a vacuum leak.

Dec 17, 2006 | 09:07 AM

Doug 87L98

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Drifting

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From: Doylestown PA

Thanks guys.

My son is at work now. We will check it out when he gets home.

Dec 17, 2006 | 09:39 AM

nyernga

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From: Conyers Ga

Mine did this back in August right before a long road trip. No codes but it turned out to be the O2 sensor.

Dec 18, 2006 | 11:50 AM

Doug 87L98

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Drifting

Joined: Dec 2004

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From: Doylestown PA

Quote:

Originally Posted by nyernga1

Mine did this back in August right before a long road trip. No codes but it turned out to be the O2 sensor.

Thru a minor miss-hap, my sons car ended up at the dealer. So while it was there I had them pull any codes. The O2 sensor was the culprit.

Again, Thanks for your input.

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