IDLE SURGE(cannot get it to quit)

[bottledgt]

ok, this is on a 91 eagle talon N/T. it starts out cold and and idles fine for about 10 sec onds, then goes to the nice 1400-1700 surge that gets slower and slower until it warms up then its gone. totally fine as long as the car is warm. then when the car is cold again there it is again. ive tried tps, isc testing all of those parts (test fine) adjusting tps, adjusting idle. i give up. i dont know what else it could be. the only thing that seems to cure it, is to unplug the single wire switch oin the throttle body, but then it doesnt idle fast when cold, and gets horrible gas mileage. does this ring a bell to anybody? am i not adjusting something right? the car ate a ecu last year(it surged then too). it just died and wouldnt start. it wouldnt turn the fuel pump on. i took the ecu apart and it was fried. so i got anther one, but im thinking that this idle surge thing is kinda hard on the computer cause it keeps cutting the fuel on and off, and thats what went bad on my ecu was the fuel circuit. any ideas

 

[laserblue]

My engine idles fast [nice and even] when cold, for about 30 seconds then I get surge for a couple minutes, and then the rpms graduately slow down to normal. . . SOUND FAMILIAR?
Cold weather makes it much more noticeable than during the summer months.... So I figure this - My cold idle air valve [whatever the official name is??] is open [as it should be when the engine is cold] but it's letting too much air in. This, in turn, makes the idle too fast, and the ECU attempts to correct it [which is proper]. The ECU will cut fuel off if the idle is over ~1500rpms and the throttle lever 'at rest' switch is activated. Then, when the rpms go down, the ECU will think "okay, I'll let the fuel flow again," which brings the idle back up and starts the surge cycle all over again...... PHHEEEWWWWW!
Eventually when the cold idle valve thingy closes [warm engine] the idle drops to where it should be.
I don't know where to look and how to fix that valve!!!!
If you find out some info, let me know. Until then I'll just let people point and stare at my reV-REv-rEV-Rev-rEV-REV-Rev car.

 

[babell2]

My 90 AWD has a little idle surge. But only seems to do it when the AC is off and the car is rolling. I attest it to my disconnecting the coolant lines that go to the throttle body. As soon as I stop the car the idle stabalizes and settles at 750 rpm where it should be. I believe there is a reed switch or speed sensor in the spedo that tells the ECU to run faster. Could you folks have bad switches? Just a wild thought... I haven't researched the theory yet.

 

[tsi_turboawd]

replace the TB O-rings

 

[Keenman]

I also have this same probelm...I had to get my computer replaced a while back and it went away, but just today i got my car back from the shop with a new cylinder head, and timing belt
(and a $1,485.00 bill) and it revs again just like the rest of yours does......i was thinking about taking it back to have them look at it but if what you guys says is true and its not that big of a deal then i wont worry about it...just wondering if any of you guys were able to fix it and what you did...also could it have anything to do with the new head and timing belt...thanks