Grand AM High Idle On Cold Start

[hummvee2134]

Hey,

I have a 96 grand am 3.1 and on a cold start this thing will idle around 2000+ rpms. once it warms up i can restart it and everythings normal. This problem never happens in the summer... only when its cold.

Any ideas? Ive already tried replacing the iac and cleening all in there. the throttle body is also well cleened.

i would appreicate the help

[xeroinfinity]

Welcome to AF.

Did you calibrate the IAC ?
Also did you clean the port it sets in ?

Other then that your throtle linkage could be sticking or some other emissions system components are bad.

Get it scanned and see if thiers and hidden codes.
Might also check for small vacum leaks.

[hummvee2134]

Thanks for the responce... There are no codes and the iac is cleen... I looked on the computer and its telling me the iac is being opened to that high idle.. could there be something telling the cumputer to give the car a high idle? i know on my girlfriends regal she had a temp sensor relpaced to solve an idle problem ....

[xeroinfinity]

Well you didnt answer my other questions......

Also after you replace the IAC, you need to reset/clear the codes.

[hummvee2134]

there were no codes to begin with.... would you know what factors the computer takes in to decide what to set the idle speed to?

\ive tried lamost everything i can with this thing... checking for vaccum leaks like ya said, cleening the iac, and calibrating it.

ive looked on this site before and seen problems exatcly like mine (relating to the cold in all) but no one seems to have a solution.

id like to figure this out before i send this car to the crusher

thanks....

[xeroinfinity]

The crusher!?

the IAC is controled by the PCM, it makes adjustments in idle speed depending on running conditions of the engine like, the AC, power steering and outside temps(cold or Hot).

It sounds like the IAC is not calibrated correctly.
It should measure 1 1/8 inches from the mounting base to the tip of the pental, if not it will have problems with idle.

Good Luck

[J-Ri]

How does one calibrate an IAC valve? And is it only when replacing it with a new one? I took mine out to clean it, and had a high idle (no tach, but about 2K) for about a month. I'd just like to know incase I have to replace one on a customers car... Don't think they'd put up with it

And if you decide to send it to the crusher, I'll take it off your hands, I'll even give you 2x scrap price

[xeroinfinity]

Yeah J-Ri, you set the pintal tip to 1 1/8" from the tip to the mounting flange.
Some you push in to set, others you turn, the one's that turn usualy state how to adjust.

Plus, when it's close to 0 outside your car will idle higher then the normal 1000-1200rpms, my GT idles about 1600-1800rpms when it's that cold out. As soon as it warms up the idle drops though.

[hummvee2134]

wow 1800 rpm idle? when my ga is idling even like that i find it hard to stop
... it just wants to take right off....

the worst ive had it is were it idles at like 2500 .Sometimes if i let it sit for awhile it ll drop the idle down on its own. But as i said if it doesnt once the engines warm if i just restart the car everythings good. it ll idle at 1000 - 1200.

i tried doing what u said to the iac, as dissapointing as it is it still has the idle problem .

i read something recently that shorting wires on the 3100s can sometimes mess up the refrence voltages for the computer and cause thigns to mess up.. it was a tsb for like the mid 90s berettas along with a few other 3.1 cars.. not the grand ams tho.

[xeroinfinity]

Well thiers only about 3 things that'll cause high idle...
Sticking throtle linkage, the IAC system and your emissions/ engine control system.

My GT (mostly stock)idles high only when the temps are realy low, 32deg or lower.
I figure the air passage in the IAC/TB sucks the cold air through and causes it to frost up(plus I have a CAI), with in 2-3mins it drops to 1000-1200rpms.
As soon as my temp gauge moves up, the idle will drop to 650 rpms.

It's strange cause my lightly moded(hehehe) SE doesn't do anything abnormal ever.

Only other thing I can think of is install a block heater.


Good Luck