C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

1990 6 spd IAC problem

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Old Dec 20, 2015 | 03:47 PM
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Default 1990 6 spd IAC problem

1990 L98 TPI 6 spd.

Had car two years. No problems till two months ago.

The car was stalling at lights and hard to start. I reset the IAC usingf the procedure with the ignition key and it ran fine. But it seems it needs the IAC reset everytime I drive it. Say two or three times per month.

Any thoughts?
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Old Dec 20, 2015 | 04:35 PM
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try cleaning it
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Old Dec 20, 2015 | 07:42 PM
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Default Cleaning

I removed the inlet duct and cleaned the inlet with a soft toothbrush and cleaner and removed the top plate and cleaned/blew out with compressed air.

I did not remove the IAC motor itself. Does that need to be removed and cleaned. Are there any springs or parts that will come apart?
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Old Dec 20, 2015 | 07:50 PM
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look on youtube moveing pictures always help
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Old Dec 20, 2015 | 11:29 PM
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Originally Posted by PETERCOP
The car was stalling at lights and hard to start.
I recommend a minimum idle adjustment:

https://www.corvetteforum.com/forums...post1570563689
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Old Dec 21, 2015 | 12:29 AM
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Originally Posted by PETERCOP
I removed the inlet duct and cleaned the inlet with a soft toothbrush and cleaner and removed the top plate and cleaned/blew out with compressed air.

I did not remove the IAC motor itself. Does that need to be removed and cleaned. Are there any springs or parts that will come apart?
One more time, baby. Take the TB off, take the plate off, take the IAC off, take the IAC housing off. Clean it all with brake cleaner. Be very careful with the IAC. GENTLE spray on the pintle and wipe it. Reassemble with NEW GASKETS.

When you are done, check timing and set it to 6 if it isn't. Get a scanner and with the car running at operating temp and everything but the motor off, set it to 20 counts. I wouldn't use the FSM method. It assumes everything is stock and in perfect working shape. After that, set the TPS. Assuming that the scanner doesn't point out any air leaks while adjusting it.
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