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95 prizm
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Discussion Starter #1
I have a high/fast idle problem I was wondering if anyone can help me out with this cause its kinda driving me crazy.

when I start it up in the morning or after its been sitting it revs at like 2k and doesnt go down till its at normal temp. then it will go down to about 1k, but then when I start to drive it and stop at a light or something it goes up to almost 2k and itll slowly go down or when I press my clutch in it will go back down to 1k till I let off. also when im driving and put it in nuetral it fluctuates from 1l to about 1.5k not fast just like a steady up and down.

Ive checked for vacuum leaks and have found none ive changed all my plugs and cap and all that, but still nothing.

also my car used to be auto but I swapped it to manual and still have the auto ecu, but I dont think that has anything to do with it cause this only started alittle after winter when it was really cold out so I thought maybe it was just the cold, but its been pretty nice out the last couple of days and it still does it.


anyone have any ideas:confused:?
 

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95 prizm
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89 Posts
Discussion Starter #3
where is the IAC located at? and is it pretty easy to get to so I can take it off to clean it out?
 

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where is the IAC located at? and is it pretty easy to get to so I can take it off to clean it out?
it's directly under the throttle body, it has an electrical connector plugged into it. to take it out u need to remove the entire throttle body assembly. try cleaning it first though before u dive into taking it out. if u spray too much throttle body cleaner into the throttle body at once the engine will be hard to start when u try to turn the car on. jusy spray small amounts at a time into the diamond shaped hole inside the throttle body and clean the throttle bore real good too. if its hard to start when u turn it on just give it a little gas and u should be ok.
 

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95 prizm
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Discussion Starter #5
I did that today and drove to the store and it went back to normal for alittle then it started again :headbang:. so could that possibly mean that I need a new IAC unit?

1.tried sprayed into the diamond shaped hole for the IAC which worked for alittle then went back to acting up.
2.throttle cable is fine.
3.not sure how to check the TPS

also is there anyway to take that top part of the throttle body off without stripping out those stupid allen head bolts so I can clean that out better?

another thing I read a post on here which someone had a fast idle and someone said to hold the idle high and unplug the IAC which I did but it did nothing it just stayed where I had it held?
 

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a haynes manual will show u how to check the TPS, it sounds like your idle problems could be caused by a misadjusted TPS. also have u checked your ignition timing?
 

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95 prizm
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Discussion Starter #8
so I fixed the high idle problem my thermostat was bad, but my idle still moves up and down when I coast in neutral till I come to a stop then it stays at normal. so what could be causeing that?
 

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try taking the postive terminal off for a few minutes then putting it back on causing it to reset the ecu. See how that works
 
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