[ste]

saab ng900 turbo - every now and then the cel will appear and the car will start driving with a constant high idle basically i dont have to put my foot on the accelerator and the car will drive itself also at a stop the car will idle up and down before settling slightly above the norm 1k

any help appreciated

 

[earthworm]

Please, all the details.

Miles ?
Year ?
Is all of the maintenance up to date ?
I suspect the IAC and or the throttle body, but a diagnosis must be done.

 

[green machine]

As E.W. has said, "Please, all the details"..... Auto Box or manual, year etc. Does the "drive itself" feature start imediatley at start up or as vehicle warm up occurs? Besides what has been mentioned in the prior post. I have seen a failing coolant temp sensor cause odd "cruise control type" and idle behavior. It tricks the ECM which opens the IAC to give enough air to run the car at various RPMs even with the t-plate closed. The more detail the better we can help.

 

[PMI]

...I have seen a failing coolant temp sensor cause odd "cruise control type" and idle behavior...

I hope you mean the Intake Air Temp sensor...

 

[green machine]

I hope you mean the Intake Air Temp sensor...

Nope the coolant temp sensor on the rear of the head just under the intake. I had an issue about 2 years ago on my 900s (granted it's a 2.3L). I'd come to a stop and RPM's would stay at wherever I left off the throttle (neutral or clutch in) or upon removing your foot from the pedal there was no decel. Key off and restart it, it would idle normal with slight fluctuations. Hit the gas and RPM's would hold wherever you left off. I popped the hood, t-plate was closed but she was holding at 3G. Described the issue to tech support from another site (Hadn't found you good folk yet) and I was told to check IAC and fuel injection coolant temp sensor. IAC was free, I cleaned and reinstalled it, but it didn't fix the issue. Temp sensor fixed it. I through it out there because it was suggested to me at one point and it DID fix mine.

 

[PMI]

Ah, I know which sensor you mean now. Interesting... learn something new every day,

 

[green machine]

Ah, I know which sensor you mean now. Interesting... learn something new every day,

Off topic.. Nice weather out here in MKE this week (In town on buisness). I think last year about this time of year I was dealing with snow out here already