1997 Other Saturn Models idle speed

Tiny
PEGGYLOU
  • MEMBER
  • 1997 SATURN
  • 4 CYL
  • FWD
  • MANUAL
  • 280,000 MILES
My idle speed suddenly went to 2500 rpm from about 800 rpm and will not come down even when the car is warmed up? Also my son has a 98 sl1 saturn and it is running really rough when you first start it for about 10 seconds, also there is a lot of black carbon on his muffler, just put pluggs in and the old onesy seemed almost too light colored, it also idles about 1200 rpm for a long time after starting, thanks
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Wednesday, July 9th, 2008 AT 7:55 PM

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Tiny
RASMATAZ
  • MEMBER
Too fast an idle speed. If an engine without computerized idle speed control is idling too fast and refuses to come down to a normal idle speed despite your best efforts to back off the carburetor idle speed screw or air bypass adjustment screw (fuel injection), air is getting past the throttle somewhere. Common leak paths include the carburetor and throttle body gaskets, carburetor insulator spacers, intake manifold gaskets, and of course, any of the engine's vacuum fittings, hoses and accessories. It is even possible that leaky O-rings around the fuel injectors are allowing air to leak past the seals. Another overlooked item can be a worn throttle shaft and a defective idle speed speed control motor/valve stuck in the extended (high idle speed) position/throttle position sensor. Also the throttle plate could be binding in its bore and kinked accelerator cable, coolant temperature sensor might not be operating properly misleading the computer that the engine is still cold and computer throwing fuel at it raising the idle speed.
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Wednesday, July 9th, 2008 AT 8:07 PM
Tiny
RICKY_O
  • MEMBER
Respectfullly, the '97 Saturn was not a carburated model.
One thing I have found useful on other models when they started rough and began idling too high was to simply turn it off, remove the negative battery cable, wait 30 seconds and then reconnect it.
This usually clears the programming from the control mods and it reads fresh from the EPROM on the next start. Sometimes when a sensor or other combination of events whacks out the code or leaves the wrong info in a variable, the controllers think the conditions are different from what they really are.
If it doesn't work, what have you lost?
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Monday, July 21st, 2008 AT 3:40 PM

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