Idle will not come down when stopping
Thread Starter
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Joined: Jul 2008
Posts: 51
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From: Shelton Connecticut
Idle will not come down when stopping
I have a 1987 stock 'vette with 123,000 miles on it. The day before we left for Carlisle, the engine started to hold a high idle when I stopped at lights etc. Prior to this there were no problems with the idle dropping to @600 RPM in drive while stopped. Now it stays 900 - 1000 when I stop and goes to 1400-1500 if I shift into neutral. I can get it to drop by "bliping" the gas pedal. I have sprayed the throttle body plates and interior throttle body from the front with cleaner as instructed on the can (STP) but didn't change anything.
Any help will be appreciated. Thanks in advance for your help
Any help will be appreciated. Thanks in advance for your help
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
With that many miles on it I would bet you have worn a throttle shaft bore in the throttle body. Grab hold of the linkage and see if you can move it back & forth. What is happening is it is slightly hanging up because of the slop in the shaft bore. Blipping the throttle knocks it loose.
Thread Starter
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Joined: Jul 2008
Posts: 51
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From: Shelton Connecticut
I have company coming now so I will try those things as soon as I get a chance and let you know the results. Thanks for the suggestions. BTW, where would I have a vacuum leak that blipping the throttle would take care of ????
Team Owner
Joined: Aug 1999
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St. Jude Donor '10
Turned out to the 90 degree angle vacuum fitting underneith the injector cover on the driver's side.
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Joined: Mar 2009
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its still plugged in and i noticed some mpg loss. Just recently idles high. Yesterday i was driving and it just died out of no where. Drove 100miles and it ran fine and idled high. Then it idled fine the next day then today its idles high no matter what.
Safety Car
Joined: Oct 2008
Posts: 4,689
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From: Yucaipa CA
when it does it open hood and you will see the linkage is slightly away from the idle stop screw. push the linkage against the idle stop screw and I bet it idles down.
time for a rebuilt throttle body or add a extra spring to get it to close. Is what causes it. The throttle blades over time wear into the bores and hang up a bit and the return spring gets weak over time. It's that quik snap of the accelerator that forces the blades shut.
time for a rebuilt throttle body or add a extra spring to get it to close. Is what causes it. The throttle blades over time wear into the bores and hang up a bit and the return spring gets weak over time. It's that quik snap of the accelerator that forces the blades shut.
Advanced
Joined: Mar 2009
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its not that it sets on the screw everytime. The previous owner has two springs on there to help pull back. I have a 1/4inch of threads sticking out the back on the idle screw is that too much? I unplugged sensors, replaced dry rotted vac caps made sure lines were tight. Replaced iac as mentioned before. Unplugged oxy sensor no diff. What is next? I can just back the screw out and drive i guess.
Instructor
Joined: Dec 2007
Posts: 111
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From: Muscatine Iowa
its not that it sets on the screw everytime. The previous owner has two springs on there to help pull back. I have a 1/4inch of threads sticking out the back on the idle screw is that too much? I unplugged sensors, replaced dry rotted vac caps made sure lines were tight. Replaced iac as mentioned before. Unplugged oxy sensor no diff. What is next? I can just back the screw out and drive i guess.