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throttle body/iac problems...stumped...

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Old Jun 18, 2011 | 06:48 PM
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Default throttle body/iac problems...stumped...

ok. i just changed my alternator due to the power steering line leaking on it... awesome...both fixed.

now it seems like the throttle wants to stay open under about 10%....like a built in cruse control...automatic high idle. if i hit the gas just a little it will stay at around 1600rpm...but if i go up to 2500...it will stay there...

all sensors putting out good voltage.
ive tried a different iac...and tps. no change.
retuned some idle air tables and recalibrated maf. (long term trims were high)
even drilled a small hole in the throttle body blade....

i put on a fast 92 and a janzer 95mm tb a while ago. but never had this problem with this setup. never done this. ive had this setup for 3-400 miles...

its pretty annoying.

its like something is physically making the throttle body stay open...only thing i can think of is the iac...not sure why its doing it now though...

anyone with advice or similar problems?

im almost thinking of putting a small return spring on the tb itself....
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Old Jun 18, 2011 | 06:53 PM
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also. if it does start to idle high or stay that way. i can blip the throttle and it will go back down.

pcv system possibly? ill try replacing the valve...
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Old Jun 18, 2011 | 07:23 PM
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checked pcv system...everything works...no leaks..

im thinking its the iac valve....so ive pulled the one on there...replaced it with another one i had...same thing...even plugged on in externally with the car running and the valve was moving in and out...

im thinking its the iac....wiring or something? ive cleaned it, and and hole...but still high idle...im guessing for some reason its not working and once the engine gets a little air above the throttle body it just keeps wanting it...keeps the blade open somehow...
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Old Jun 18, 2011 | 08:34 PM
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I'd recheck for a vacuum leak.
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Old Jun 18, 2011 | 08:58 PM
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alright...will do...

i have a catch can with a built in pcv in the garage....good time to put it on too....replace all the hoses...

i sprayed carb cleaner on all the lines and connections...
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Old Jun 19, 2011 | 12:23 AM
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You may also want to try Re-setting the TPS sensor. Its very simple. Just unplug the TPS connector on the T.B., turn the key to the run position( no start ) for a few seconds, then turn key back to off. Re-attach TPS connector then start.

Hope this helps.
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Old Jun 19, 2011 | 12:03 PM
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I've reset it a few times. Im going to see where my iac count is adjust the throttle body. Then reset Tps. Then possibly play with throttle decay. Its real slow coming back down to idle.
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Old Jun 19, 2011 | 06:02 PM
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ok...so ive tried tons of new things.

opening/closing blade with set screw...adjust iac count...reset tps...no work

even adjusted (tried maxing and lowering iac count) and it still does it.

just seems like if im barely on the throttle it wants to stay there. and the iac doesnt adjust to compensate idle speed....(tried 2 different iac's)

when i unplug the iac...the idle doesnt stick....tb doesnt want to stay open.
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Old Jun 19, 2011 | 07:16 PM
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update on iac count and tps reset.

after i adjust the tb blade to get my iac number to around 55. i will kill the car, unplug tps, key on, key off, start car, my iac count goes to less than 10...then if i redo it, it does the same thing.

do i also need to do some sort of iac reset?
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Old Jun 20, 2011 | 10:45 PM
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bump!!!! someones gotta know...

im thinking burnt pin pcm...something messed up in pcm..or burnt wire.

got a hard time thinking is something in my tune thats now off.....
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Old Dec 17, 2011 | 03:35 AM
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Same problem here. I am finding tons of threads with the same problem, but no one ever figures it out... Any new ideas? I have tried almost everything, and still get the random 2500 RPM idle once in a while...
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Old Dec 17, 2011 | 10:00 PM
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Will a stock-cam car run ok with the IAC unplugged?

Or can it be tuned out until I figure out what the problem is?
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Old Dec 18, 2011 | 08:56 PM
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mine was to the point where it ran better without it plugged in...lmao....

i ended up doing a tps reset. set your iac counts in the prescribed range.

i used my hptuners to adjust throttle decay and cracker rates...it worked. not sure how or why...but it did. ive read this helps with most the iac problems...
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Old Dec 18, 2011 | 09:13 PM
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Thanks! At least now I know I can run with it unplugged until I have time to tune it.
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Old Feb 19, 2013 | 01:05 PM
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Anyone figure this out? My car is doing the same thing. Its pissing me off.
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Old Mar 10, 2013 | 09:39 AM
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I've ran in to a problem with mine where the car acts completely retarded if I plug the iac in. Typically The pintle should seat, then pull back 40 steps when the keys turned on. Mine doesn't seat when the key is turned on it just dances around going in and out back and forth.
Pulled the harness and ohmed out each wire: no dice. Changed ECM, changed tunes. Changed tunes in new ECM. My iac works fine in another car. Another cars iac (that works fine in the donor) does the same **** in mine.
Car will not idle with it plugged in.
So I've been cruising around for a year with it un plugged. with the stock cam it wasnt really an issue, but now with an aftermarket cam, it's become a real pain in the ***.
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Old Mar 11, 2013 | 03:26 AM
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Well from my personal experiences this happens when you go with an aftermarket throttle body. They either A have bad shaft bearings or B have vacuum leaks . Either way never had this problem with the good ole stocker. Hope this helps
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