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  1. #1

    Default High idle after cleaning throttle body.

    96 GMC k1500 Suburban with a 350. I took off my throttle body and cleaned it with carb cleaner. It had about a 1/4 inch of gunk underneath the butterfly. Got it shiny clean. I replaced the throttle body gasket on the intake too. I have 1000 rpms at idle in gear, but when driving, the idle doesn't drop back down right away when I let off the gas. I believe the idle is supposed to be around 800 rpms? Any advice? Thanks.

    1996 GMC Suburban K 1500 "The Love Boat"
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  2. #2

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    Is it running fine other than high idle? A vacuum leak would usually do the opposite and make it run rougher. Not sure if yours requires it as my 04 truck doesnt but on some vehicles an idle relearn is necessary if you remove the throttle body. that is the same thing that happens in my wifes nissan when I clean the throttle body and its a certain number of timed pedal presses and key turns etc.
    David
    2004 Silverado 2500 Crew Cab 4x4, AMSOIL EA air filter, Granatelli MAF sensor, Throttle body spacer, Magnaflow exhaust (true dual to 2 in 1 out muffler), 6" ProComp lift (add a leaf and 5" superlift rear block), Bilstein shocks, 35's (Cooper Disoverer ST) and 4.10 gears, Rhino Liner, EGRUSA fender Flares and widow visors, extended stainless steel brake lines, firestone airbags w/onboard air compressor, Pioneer Avic X940BT navigation, Accel backup camera.
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  3. #3

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    Quote Originally Posted by dsfloyd View Post
    Is it running fine other than high idle? A vacuum leak would usually do the opposite and make it run rougher. Not sure if yours requires it as my 04 truck doesnt but on some vehicles an idle relearn is necessary if you remove the throttle body. that is the same thing that happens in my wifes nissan when I clean the throttle body and its a certain number of timed pedal presses and key turns etc.

    Thanks for your reply dsfloyd. It runs smooth as glass and there is no vacuum leaks. All I did is clean the throttle body thoroughly. I disconnected the battery for 30 min to clear the code and let the pcm relearn, but with no result. I did however find something interesting. When I wiggle the connections at the pcm, the idle increases alot like there is a loose connection there. It's hard to brake this 5000 pound beast when it's idling high. My brakes were getting hot last night.

  4. #4
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    Default

    Carb cleaner is an enemy of the TBI.. but i would actually think that somehing with the IAC, or the TPS is shot. I would start there, and yes i get the giggling wires.. Also i know you only cleaned the TBI, but there is a chance that you have an intake gasket leak as well.
    Mike

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  5. #5

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    Quote Originally Posted by murdog94 View Post
    Carb cleaner is an enemy of the TBI.. but i would actually think that somehing with the IAC, or the TPS is shot. I would start there, and yes i get the giggling wires.. Also i know you only cleaned the TBI, but there is a chance that you have an intake gasket leak as well.
    Thanks murdog for your reply. I replaced the IAC 2 days ago and replaced the intake gaskets 6 months ago. I sprayed carb cleaner along the intake and the base of the TB to double check. The only thing I haven't replaced is the TPS. That's going to have to wait until payday.

  6. #6
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    I would first trouble shoot it.. you can do a sweep test, that will tell you if it is bad or not.. there is a procedure here on the forum how to do that. Then you arent just throwing parts at it.

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