1998 Saturn SW2 Fast idle

Does the IAC have a signal? you should be able to remove and turn on ignition and see and hear it drive, check this first.

Just to add to this one it sounds more like a bad coolant temp sensor its so common for them to fail and cause a slew of symptoms. Also inspect the inside of the coolant temp sensor connector. If the terminals are blue or green instead of silver then you will have to replace the connector as well. The sensors leak coolant into the connectors corroding them.you can check the iac but they dont fail often on those model years.on the 2000-2002 i have seen them fail a little more.

Happy to have further input especially from a expert on the type we are discussing, thanks saturntech9 for the input.

Your welcome glad I could help.

There are no codes popping, coolant sensor (front) has been replaced), idle control has been replaced, yet the fast idle continues. Am at wit's end on this one!

Meant to add that the oxygen sensor (front) has been replaced, also with no effect. /Hickoryman

Have you checked for vacuum leaks yet?

Checking for vacuum leaks was one of the first checks we made. My mechanic says there are none.

So do we have any codes in the computer? I have a similar problem with my 1999 saturn sl2 if its idling high and i turn it off and restart it the idle comes back to normal.It will sometimes set a code for throttle position sensor low voltage.It has something to do with the throttle position sensor circuit.

Didn't mention it before, but we did check for codes and found none. I'll look into the TPS situation.... makes sense!

Next time you have the high idle unplug the tps and see if the idle goes down?Mine did then when i plugged it back in while it was idling the idle hasnt been high since.But my high idle comes and goes.

I didn't want to speak too soon on this, so have used the past few days as a "test run". It does appear now that this chapter of the "Saturn Saga" can be closed. Replacing the TPS in spite of no codes showing at all has brought the idle to where it should be. And, I can drive down the streets without having to use the brakes to slow down due to the fast RPM which plagued before. Installing a new Idle control, cleaning the throttle plate, and a new oxygen sensor (for which a code did appear a week or so ago) may delay other events later, but do not appear to be the real solution for the idle.

Also have noticed that I can remove the key from the ignition easily each time instead of at times having to restart the engine to get a "normal" idle before the key will release. Looks as though there could have been a series of issues, some obvious and some not so much, that may be normalized due to the computer seeing normal signals! Thanks for your patient advice on this one!

The key not turning off easy has nothing to do with the tps or high idle.But your welcome glad to hear your idle issues are solved.