Idle 'Surge'?

[Zikkitzo]

Heres one problem that I cant find anywhere in my manuals, on the net, or in the car. I set the idle to around 800 RPM when its been running a while. Then when I drive it for a while... then come to idle a while, it will be at 2000 RPM or MORE! I set it back down and it happens again. Iv tried tread loc on the throttle cable bracket and the BISS (idle screw on the throttle body) so its not vibrations messing with it. Im not getting any DTCs (engine error codes). I dont have the money to just start replacing stuff (Im still trying to save up to replace the transmission that the shop screwed up) Iv tried looking at the numbers from the datalogger but I just kinda go with that. I havent had time to figure out what all those numbers mean yet.

Thanks

[Damon]

Throttle position sensor TPS or idle control motor. Seems like we've all had idle gremlins and those two parts are usually the culprit.

[stevep]

If the ISC is working correctly you won't be able to set an 800 rpm idle, the ECU wants 750 and will try to move the ISC pintle in to get it until it runs out of range because you have opened the BISS too far. That will cause fast idle problems when the EDU decides to open the ISC pintle.

Jeff L has a good ISC page, better than any of the DSM VFAQ's. We use the same ISC's. www.stealth316.com/2-isc-iac.htm

Remember to ground both the timing check and the EDU diag mode connector (pin 10) when setting the base idle speed. That locks the ISC at it's default range so you can adjust the amount of air the BISS bypasses.

Steve

[Zikkitzo]

Erm... yeah. Id need some help with that. Any takers?