What causes idle speed to increase every 10 seconds?

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Apr 20, 2004 | 07:44 AM

Bob 97SS

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Joined: Nov 1998

Posts: 36

From: NJ

What causes idle speed to increase every 10 seconds?

The idle is smooth but increases a few hundred rpm every 10 seconds. Then it drops back to normal and the process starts all over again. No codes. IAC count is around 80.

Apr 20, 2004 | 08:38 AM

badblackta

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Joined: Jan 2004

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From: Ocala, Florida

it is the IAC sensor. My moms z does the same thing. The car trys to lunge forward.

Apr 20, 2004 | 08:43 AM

scoobysnax83

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Joined: Sep 2002

Posts: 2,481

From: Arlington, VA

I would go with a vacuum leak as well. If there is a leak then the PCM is using the IAC to compensate for it. That may be why you (badblackta) think it is the IAC.

Apr 20, 2004 | 08:48 AM

badblackta

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Joined: Jan 2004

Posts: 800

From: Ocala, Florida

just sounded like the same thing going on with my moms z28, the exact same thing. And there are no vacuum leaks. Not ruling out the possibility of a vacuum leak on this car though

Apr 20, 2004 | 08:52 AM

scoobysnax83

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Joined: Sep 2002

Posts: 2,481

From: Arlington, VA

it could definitely still be the IAC, I wouldn't rule that out, but check for the obvious first like leaks. You should clean your IAC as well. Try a little carb cleaner on it