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Topic: Excessively high idle

in Forum: C4 Fuel, Emission Control, and Exhaust Systems

Excessively high idle

Posted: 8/22/22 6:06am Message 1 of 6
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I have 1984 C4 with Crossfire.  My idle was rolling and kept stalling at lights. I changed the IAC valves after doing some research. Now I cannot get the idle back down to normal. When cover the air holes where IAC valves are I can bring the idle down to about 1000 rpms in neutral otherwise I am at 2600.

Any suggestions?

Thank you




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Re: Excessively high idle

Posted: 8/22/22 8:15am Message 2 of 6
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Duncanville, TX - USA
Joined: 3/18/2009
Posts: 2246
Vette(s): 1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.

The IAC valves need to be "relearned". There is a procedure for this that requires a specific tool to block the valve(s) while doing it. I have the info at home I can send this evening if you want.




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Re: Excessively high idle

Posted: 8/22/22 8:23am Message 3 of 6
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Yes. Thanks. That would help




Re: Excessively high idle

Posted: 8/23/22 4:16am Message 4 of 6
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Duncanville, TX - USA
Joined: 3/18/2009
Posts: 2246
Vette(s): 1985 Coupe-L98/Auto,Bright Red/Carmine. 1974 Coupe-L48/4speed, Medium Red Metallic/Black Deluxe.

From the service manual...




Joel Adams  
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(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Re: Excessively high idle

Posted: 8/23/22 8:07am Message 5 of 6
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Thanks. I will give it a try




Re: Excessively high idle

Posted: 8/24/22 8:57am Message 6 of 6
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beaufort, SC - USA
Joined: 9/1/2009
Posts: 39
Vette(s): 1990 Turquoise Corvette (his) & 1990 Turquoise Corvette (hers)indy festiville car for sale

Replace the idle air control valve under the throttle body




in Forum: C4 Fuel, Emission Control, and Exhaust Systems


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