Idle all over the place

[91tsitalon55]

So yesterday i took my 91 tsi talon to get emissions and luckily passed Although when i was looking at their RPM screen and listening to the car i noticed they were all over the place ranging from 550 - 1500 is there anything i can do about this?

Thanks,

 

[92AWDHX40]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

 

[T is for TURBO]

Search "Idle Surge"
You should be able to find your answer from there

^Beat me too the punch.^

 

[gusu]

Quick list

ISC (Idle Speed Controller), will cause idle problems on deceleration and while stopped.
BISS adjusting screw o-ring will do the same thing.
CAS (Crank Angle Sensor) I can't remember what this causes the idle to do but it can also cause idle surge.
A vacuum leak will cause idle to become nearly impossible making it just want to die, if it is at the brake booster most of the time your car WILL die unless you have the brakes pressed down.
A bad ISC that has been replaced can also cause your ECU to short out causing it to act as if the ISC is bad. But the ECU being bad can kill the ISC as well. It's a vicious cycle if you don't properly check and adjust both.

Finally PROPERLY adjust your BISS screw! If you adjust it by tightening the screw only the ECU reads the mixture as if the screw were tightened to the previous proper adjustment! You WILL NOT get a proper reading until you PROPERLY adjust the BISS. There is a write up on it at VFAQ.

1G BISS Adjustment <--- There's the link.

 

[ampsyco]

mine was doing the same thing. the thermostat was bad, stuck open. if the engine never get's up to temp it will fast idle.

 

[snowborder714]

Covered many times. Check out the links above.