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Discussion Starter #1
I bought a celica supra last night and it drove fine except it was having a low idle issue where it would keep dying due to low/rough idling when brought to a stop. It started getting better and I could drive it without it dyin on me but it would still idle really low causing the car to shake, also it wasnt very respondant to throttle inputs, say you blip the throttle the engine wouldn't rev up right away but rather hesitate and if you stay on the throttle it would rev up and drive nicely. Today I start the car, ok, its running like last night, keeps dying on me until it warms up. So I get where i need to go and I'm ready to leave and as im driving i notice the car is accelerating on its own and the idle was coming up to 2.5k when the car is idling at a stop. I get home and its only gotten much worse, now it ides at 4k rpms, nothing i can do to stop it. The throttle body is closed I checked for other vac leaks before the TB but that would have to be one hell of an obvious vac leak to make it idle that high right? Any ideas? I read it might be a sensor but I don't have any code reading equipment. Thanks in advance
 

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My intake piping is oem and all cracked to hell. I am in dire need of intake piping, stock or preferably aftermarket but I need it on the cheap if anyone has some parts laying around. I can't figure out where that much of a vac leak would be coming from even with the oem piping I sealed over with duct tape for troubleshooting purposes its still wanting to rev up to ~4 grand. Gonna start tearing shit apart tomorrow and track down some new intake parts.
 

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Sounds to me like the throttle position sensor. Computer needs to know when the throttle plate is closed so it can go into idle mode. Also needs to know the instant you've opened the throttle so it can give it a little squirt otherwise you have lag throttle response. Check the connection to the TPS, then check the adjustment (there's procedure posted in here somewhere), and if you can't adjust it, then replace.
 

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if your intake piping is cracked and leaking then there is more than likely un-metered air entering after the afm, thus giving the ecu an innacurate signal, more than likely causing erratic idle and poor throttle response. If need be go nuts with some electrical tape to seal it all up and see if it works better. If it does than quickly drive to the junk yard and grab that shit.
 

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Discussion Starter #7
ok, the connection to the tps seems fine, so thats sorta ruled out unless its gone bad. As far as the unmetered air coming in, there would have to be a hell of alot of air coming in to make it want to idle at 4k. This is like the TB is open or something.
 

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i would check into your IAC i sounds like that could be freaking out
Sure sounds like your IAC to me. Squeeze that hose shut and watch you idle drop down.If it does there is your problem.
Do you know what and where this device is? and what hose I am talking about?
It makes that squeak squeak sound 3 times when you shut the engine off. IAC. The wires are probably cracked or broken to that device. My engine did the exact same thing you are describing when one of the wires broke.
 

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Discussion Starter #10
I started it up this morning, wow its gotten worse now it shoots right up to 5k rpm. I started pinching off the hoses that go to/from the iac and the rpms came down very slightly but not much at all (maybe 4.5k rpms) this is driving me nuts!
 

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Discussion Starter #11
plus I dont like starating the car when its cold and having the motor run up to 5k that is such a bad idea especially cuz it has 188k on it.
 

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Discussion Starter #12
Alright I found the problem, it was a screw that had vibrated its way loose which controls where the throttle body closes. Thanks for the help though! I'll put up some pics of the car later. Oh, I'm pretty sure its only running on 5 cylinders, thats what it sounds like anyway. Time to do a compression test. When idling it only sounds like its hitting on 5 cyl then it wants to die but it does continue running though.
 
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