crazy problem
Thread Starter
Heel & Toe
Joined: Oct 2008
Posts: 15
Likes: 0
crazy problem
The car is a 1982 Corvette and has 63k miles. My problems are cold and hot idle. When the engine is cold first start of the day it will idle around 1500 to 1800 RPMs out of gear until it gets a little temp built up and then drops down to within normal range. Then when it is at running temp in gear it idles at around 500 to 525 RPMs and is a little choppy, add a little gas to run it to around 600 to 625 RPMs and it runs smooth at idle. There are no problems when driving. I have changed the O2 sensor, the Temp sensor with the new type 2 wire sending unit that is recommended. The vacuum holds strong at 22 and does not jump around or fade. The TPS is set at .525 volts. The fuel pressure is at 12 PSI. Could this be an ECM problem that it is misreading the info it gets or could the TPS be bad and sending wrong info? Any other suggestions to look for would be greatly appreciated.
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
The car is a 1982 Corvette and has 63k miles. My problems are cold and hot idle. When the engine is cold first start of the day it will idle around 1500 to 1800 RPMs out of gear until it gets a little temp built up and then drops down to within normal range. Then when it is at running temp in gear it idles at around 500 to 525 RPMs and is a little choppy, add a little gas to run it to around 600 to 625 RPMs and it runs smooth at idle. There are no problems when driving. I have changed the O2 sensor, the Temp sensor with the new type 2 wire sending unit that is recommended. The vacuum holds strong at 22 and does not jump around or fade. The TPS is set at .525 volts. The fuel pressure is at 12 PSI. Could this be an ECM problem that it is misreading the info it gets or could the TPS be bad and sending wrong info? Any other suggestions to look for would be greatly appreciated.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
My 82 was doing that when I first got it. At first I found an idle stop screw on one of the throttle bodies( I forget which one) and that worked with no problem. Then I found that my balancer slipped a little. Throwing off the timing mark. I bumped the timing up by ear and the idle was a little too high but it ran fast! I backed that idle stop off and it's been perfect for almost 10 years now.
My advise, try bumping the timing up first! Regardless of what your timing mark says.
Then go to the idle stop screw if that's not it.
My advise, try bumping the timing up first! Regardless of what your timing mark says.
Then go to the idle stop screw if that's not it.
Le Mans Master
Joined: Jul 2000
Posts: 6,664
Likes: 162
From: columbia city in
does sound like the idle air controls may be dirty .15-1800 rpm on cold start sounds a little high.then down to less then 600 rpm when it starts to warm up.if you think the tps is giving you a problem you can check it to see if it is working smoothly with a ohm meter.you may also have a small vac leak that is re sealing after it warms up.
