1998 Saturn SW2 Fast idle

Tiny
HICKORYMAN
  • MEMBER
  • 1998 SATURN SW2
  • 1.9L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 97,000 MILES
Some months ago, the Saturn started to fast idle when put into neutral on stopping, at a stop sign, etc. It goes up to 2000 rpm, sometimes after starting at a slightly lower speed, If the engine is shut off and restarted, the idle comes down to 800 as it should. The ICM was replaced and the baffle cleaned with carburetor fluid, but no difference.
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Tuesday, December 30th, 2014 AT 10:13 AM

13 Replies

Tiny
MHPAUTOS
  • EXPERT
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.
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Tuesday, December 30th, 2014 AT 12:30 PM
Tiny
SATURNTECH9
  • EXPERT
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.
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Thursday, January 1st, 2015 AT 2:54 PM
Tiny
MHPAUTOS
  • EXPERT
Happy to have further input especially from a expert on the type we are discussing, thanks saturntech9 for the input.
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Thursday, January 1st, 2015 AT 3:40 PM
Tiny
SATURNTECH9
  • EXPERT
Your welcome glad I could help.
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Thursday, January 1st, 2015 AT 4:39 PM
Tiny
HICKORYMAN
  • MEMBER
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!
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Tuesday, May 12th, 2015 AT 12:29 PM
Tiny
HICKORYMAN
  • MEMBER
Meant to add that the oxygen sensor (front) has been replaced, also with no effect. /Hickoryman
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Tuesday, May 12th, 2015 AT 12:32 PM
Tiny
SATURNTECH9
  • EXPERT
Have you checked for vacuum leaks yet?
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Tuesday, May 12th, 2015 AT 9:08 PM
Tiny
HICKORYMAN
  • MEMBER
Checking for vacuum leaks was one of the first checks we made. My mechanic says there are none.
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Thursday, May 14th, 2015 AT 5:21 PM
Tiny
SATURNTECH9
  • EXPERT
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.
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Thursday, May 14th, 2015 AT 9:10 PM
Tiny
HICKORYMAN
  • MEMBER
Didn't mention it before, but we did check for codes and found none. I'll look into the TPS situation. Makes sense!
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Friday, May 15th, 2015 AT 10:52 AM
Tiny
SATURNTECH9
  • EXPERT
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.
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Friday, May 15th, 2015 AT 12:43 PM
Tiny
HICKORYMAN
  • MEMBER
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!
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Monday, May 25th, 2015 AT 9:33 AM
Tiny
SATURNTECH9
  • EXPERT
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.
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Monday, May 25th, 2015 AT 9:52 AM

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