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

'92 LT-1 - automatic choke sometimes not working

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Old Jul 21, 2008 | 07:37 AM
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Default '92 LT-1 - automatic choke sometimes not working

Sometimes, when I start my '92, the IDLE sits at 300 - 400 RPM and eventually dies. Looks like in certain weather conditions (very humid days, just after or during rain etc.), the automatic choke doesn't work.. I have to REV the engine up for about 1 - 2 minutes before the idle stabilizes.. It's only temporary and at one point starts working again.. What can cause that condition? Is there some kind of sensor that needs to be replaced?
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Old Jul 21, 2008 | 07:49 AM
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Originally Posted by GrandSportC3
Sometimes, when I start my '92, the IDLE sits at 300 - 400 RPM and eventually dies. Looks like in certain weather conditions (very humid days, just after or during rain etc.), the automatic choke doesn't work.. I have to REV the engine up for about 1 - 2 minutes before the idle stabilizes.. It's only temporary and at one point starts working again.. What can cause that condition? Is there some kind of sensor that needs to be replaced?
Sounds like your IAC is junk. Could have a faulty MAT or CTS as well. Really need to throw a scanner on the car to be sure.

-- Joe
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Old Jul 21, 2008 | 08:05 AM
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Originally Posted by anesthes
Sounds like your IAC is junk. Could have a faulty MAT or CTS as well. Really need to throw a scanner on the car to be sure.

-- Joe
I thought that scanners will only tell you what's wrong if there's a code.. However, no warning lights/codes at all...
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Old Jul 21, 2008 | 08:38 AM
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Originally Posted by GrandSportC3
I thought that scanners will only tell you what's wrong if there's a code.. However, no warning lights/codes at all...
Nope. What if the coolant sensor is reading -13 when the coolant temp is really 215? Same thing goes with the MAT. It takes a lot to trip a code sometimes. A sensor (or combination of sensors) reading wrong could really throw off the fuel correction routines.

-- Joe
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Old Jul 21, 2008 | 09:29 AM
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Originally Posted by anesthes
Nope. What if the coolant sensor is reading -13 when the coolant temp is really 215? Same thing goes with the MAT. It takes a lot to trip a code sometimes. A sensor (or combination of sensors) reading wrong could really throw off the fuel correction routines.

-- Joe
Are there any affordable code readers that I could get myself or does this have to be done at a shop?
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Old Jul 21, 2008 | 09:53 AM
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Originally Posted by GrandSportC3
Are there any affordable code readers that I could get myself or does this have to be done at a shop?
You can download a demo copy of datamaster, and buy a cheap ALDL cable on ebay.

Or bring it to a shop.

-- Joe
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Old Jul 21, 2008 | 12:34 PM
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I would start by removing, then cleaning both the throttle body and IAC valve. Both could be simply gummed up with carbon deposits.

You might be able to rent a scan tool from NAPA or AutoZone, Olivier. They used to rent 'em out in my neighborhood store.

You can get an Autoxray EZ Read Model 2500 Code Reader for $150 or less used.

Last edited by onedef92; Jul 21, 2008 at 12:37 PM.
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Old Jul 21, 2008 | 12:48 PM
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Originally Posted by onedef92
I would start by removing, then cleaning both the throttle body and IAC valve. Both could be simply gummed up with carbon deposits.

You might be able to rent a scan tool from NAPA or AutoZone, Olivier. They used to rent 'em out in my neighborhood store.

You can get an Autoxray EZ Read Model 2500 Code Reader for $150 or less used.
Will the code reader display running data or just codes?

-- Joe
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Old Jul 21, 2008 | 01:44 PM
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Originally Posted by onedef92
I would start by removing, then cleaning both the throttle body and IAC valve. Both could be simply gummed up with carbon deposits.

You might be able to rent a scan tool from NAPA or AutoZone, Olivier. They used to rent 'em out in my neighborhood store.

You can get an Autoxray EZ Read Model 2500 Code Reader for $150 or less used.
Maybe one of the parts stores can scan my car for free.. They want to sell the parts and if their scanning tool comes up with something, they'll very likely sell the part.. I'll give it a try..
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