1984 corvette does not idle
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Cruising
Joined: Sep 2019
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From: sydney australia
1984 corvette does not idle
Hi guys i have just brought a 1984 corvette i am having trouble with the idle after it has been driven for a while . as i slow down revs drop under 500 rpm and stalls 'i have installed new fuel sensors .engine runs well on highway can anyone give me some advice as to what it could be thanks gullo
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From: Mission Viejo CA
What sensors have you replaced? How did you determine these sensors were defective?
The engine idle speed should be controlled by the IAC's (Idle Air Controllers) that are located in the front of both throttle bodies. They may be dirty. They control the amount of air that bypasses the main butterfly throttle valves. Clean the tips of the IAC's and the ports in the throttle bodies. The air passage for the IAC's is the triangular opening in the top of the throttle body, just above the IAC location, which also needs to be clean. Don't turn on the ignition while the IAC's are not installed. The IAC's can't be moved by hand. It's normal that they seem to be stuck!
The engine idle speed should be controlled by the IAC's (Idle Air Controllers) that are located in the front of both throttle bodies. They may be dirty. They control the amount of air that bypasses the main butterfly throttle valves. Clean the tips of the IAC's and the ports in the throttle bodies. The air passage for the IAC's is the triangular opening in the top of the throttle body, just above the IAC location, which also needs to be clean. Don't turn on the ignition while the IAC's are not installed. The IAC's can't be moved by hand. It's normal that they seem to be stuck!
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From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
Hi guys i have just brought a 1984 corvette i am having trouble with the idle after it has been driven for a while . as i slow down revs drop under 500 rpm and stalls 'i have installed new fuel sensors .engine runs well on highway can anyone give me some advice as to what it could be thanks gullo
Zen Vet Master Level VII
Joined: Mar 2016
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From: Southlake, TX
Your temperature sensor is bad. The L83 is very sensitive to the coolant temperature at it sends signals to the computer on rich/lean condition. This is common and the symptoms your describe says check the coolant sensor.
Drifting
Joined: Jun 2018
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From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
All good suggestions above. I can’t think what the fuel sensor your talking about could be. Do you mean the throttle position sensor TPS if so and you replaced it it needs to be adjusted. Off the top of my head I think it should measure 0.54 volts when the throttle is closed and something over 4.5 volts at WOT. (Ignition on engine off).
If the above recommendations don’t help then you could check the throttle body adjustment. The procedure is in the Factory Service Manual FSM. TBH I don’t think it’s adjustment because the symptoms would be different it might hunt at idle rather than just stall.
If you replace the Coolant Temperature Sensor CTS the new one will have an oval two pin plug which is a much better design. If it already has this plug it has been replaced.
You should also think of getting some sort of diagnostic scanner. For these cars a good option is the winALDL software which is free to download and use. The website also explains how to make a cable but there are pre-made options out there. You will be amaze at what you can see and diagnose with scanner software like winALDL.
If the above recommendations don’t help then you could check the throttle body adjustment. The procedure is in the Factory Service Manual FSM. TBH I don’t think it’s adjustment because the symptoms would be different it might hunt at idle rather than just stall.
If you replace the Coolant Temperature Sensor CTS the new one will have an oval two pin plug which is a much better design. If it already has this plug it has been replaced.
You should also think of getting some sort of diagnostic scanner. For these cars a good option is the winALDL software which is free to download and use. The website also explains how to make a cable but there are pre-made options out there. You will be amaze at what you can see and diagnose with scanner software like winALDL.
Last edited by GregMartin; Oct 10, 2019 at 05:18 AM.
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From: Mission Viejo CA
Greg, have you discovered that the OP is also in Australia?
Drifting
Joined: Jun 2018
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From: Brisbane Australia
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Adjusting the throttle bodies is the LAST, LAST, LAST thing on the list! I have 240,000 miles (386,000 km) on my '84, and the throttle bodies haven't been touched (other than spray carb cleaner), and it starts and runs fine!
Greg, have you discovered that the OP is also in Australia?
Greg, have you discovered that the OP is also in Australia?
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
Drifting
Joined: Jun 2018
Posts: 1,402
Likes: 287
From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
Safety Car
Joined: Nov 2005
Posts: 3,532
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From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
How far is Sydney from Brisbane, is it farther than the USA is long east to west? 
Last edited by Buccaneer; Oct 12, 2019 at 11:23 PM.
Drifting
Joined: Jun 2018
Posts: 1,402
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From: Brisbane Australia
C4 of Year Finalist (performance mods) 2019
Very roughly Australia and the US are about the same size. Australia is bigger until you a Alaska then the US is.
So Sydney to Perth ie east cost to west coast is similar to LA to New York. About 5 hours in a plane.
