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#1 |
Registered User
Join Date: Apr 2014
Location: Cunningham, KY
Posts: 351
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Idling high
My 87 V10 seems to always idle high. I have set the idle as they say it should be (dead 0 with the wire unplugged) and it seems to idle high after the normal warm up. I have tried retarding timing and advancing timing and it still sounds high (no tach so I can't say for sure at what rpm). I am wondering if the aftermarket idle air control valve has something to do with it, but have not tried trading it out for an AC Delco IAC. Plugs, wires, cap and rotor are only about 6 months old. Anyone have any ideas?
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#2 |
Registered User
Join Date: Oct 2015
Location: Waskatenau, Alberta
Posts: 259
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Re: Idling high
I had a similar problem with my 93 GMC. There is a gasket between your throttle body/intake that sometimes develops vacuum/air a leak. Your computer compensates for the extra air by giving it extra fuel, and the result is a high idle. No guarantees this is the problem, but it is common and wouldn't hurt to check. (this new gasket is cheap, and not overly hard to change)
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#3 | |
Registered User
Join Date: Mar 2014
Location: Corvallis, OR
Posts: 712
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Re: Idling high
Quote:
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1972 GMC Jimmy Custom 4.8L (L20)/6L90E/NP205 1989 Chevy Suburban V2500 350/Turbo 400/4.11 gears 1996 Chevy Suburban K1500 350/4L60E |
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#4 |
Registered User
![]() Join Date: Nov 2013
Location: Fowler California
Posts: 140
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Re: Idling high
Have you checked the coolant temperature sensor by the thermostat housing at the front of the motor? I believe this is what the computer uses for cold start/idle. Your truck might be staying in that higher idle if that sensor is out. looks like this...
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1967 CHEVELLE MALIBU 427/700R4 1971 CHEYENNE 10 350/350 1983 GMC K3500 454/400/205 1987 R10 TBI 350/700R4 2014 CRUZE 2.0 TURBO DIESEL |
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#5 |
Registered User
Join Date: Apr 2014
Location: Cunningham, KY
Posts: 351
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Re: Idling high
I rebuilt the throttle body back in the fall so I really don't think it is that, but I am going start looking for a vacuum leak again.
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#6 |
Registered User
Join Date: Nov 2015
Location: portage wi
Posts: 504
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Re: Idling high
like Barry said the gasket between the throttle body and intake was famous for failing and causing higher than normal idle speeds. I would still look at it even if I had just replaced it a while back.
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