Idling too fast after warmup
Thread Starter
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Joined: May 2010
Posts: 56
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From: Livermore California
Idling too fast after warmup
My '90 LT5 runs very nicely from a cold start, but once it warms up the idle goes way up... like 1600+. I can ease out the clutch and literally drive it up to 17-18mph without any throttle. I also noticed that once I put it into reverse and back up a bit the idle slows to normal. Very strange, indeed. Also, if I am at a light or otherwise stopped for a minute or so, idle speed will sometimes slowly drop to below 1000.
I thought at first maybe a vacuum leak once the engine is hot? This is my first 'Vette and I could use a bit of a starting point.
Thanks!
I thought at first maybe a vacuum leak once the engine is hot? This is my first 'Vette and I could use a bit of a starting point.
Thanks!
Thread Starter
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Joined: May 2010
Posts: 56
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From: Livermore California
I pulled the TPS off and ran it into an ohmmeter and the operation is very smooth. After reinstalling it and adjusting, the idle now seems to be lower. I cannot swing the TPS further so I will drive the car cold and see if that made any difference.
Racer
Joined: May 2009
Posts: 421
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From: van buren ar
find all the vaccume sources.then while its idling high disconnect the supply lines one at a time to determine if one is causing the leak.make sure when you disconnect the line you plug the vaccume source so as not to create another leak.if you find one that makes the idle go back down trace that line to the components it supplys.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
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From: WV
You beat me to it, I was just going to suggest cleaning the channel out that feeds the IAC and maybe cleaning off the IAC pintle.. I was having the same problem with the idle not coming down like it should, replaced the IAC and now its fixed...WW
Thread Starter
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Joined: May 2010
Posts: 56
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From: Livermore California
I am going to pull the throttle body and IAC and clean both of them this evening. From there I will reassemble and check it out. The engine has 45k on it and I do not know when it was last serviced, but judging by the crap around the TPS, the throttle body is likely full of buildup. I will post back here with the results.
Thanks for the replies :-)
Thanks for the replies :-)
