I have a 1998 Saturn SW1 with around 150k miles on it. Lately I have been having problems with it idling at around 2k rpm for no particular reason. The code it is throwing is P0122 which is for the TPS. I have replaced the TPS and this changed nothing. Whenever the car is idling fast I can shut it off and immediately restart it and it will idle normal. Sometimes it will do it when it is cold, and other times when its warmed up. Any thoughts? I'm assuming its electrical since shutting off and restarting will make the problem go away temporarily.
Saturn SW1 intermittent fast idle
- Thread starter nwjones18
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Have you replaced the infamous ECTS?
^^^
First thing to check. After that, check for vacuum leaks.
First thing to check. After that, check for vacuum leaks.
I think I have replaced the ECTS but I honestly cannot remember. I know the temp guage reades right at 3/8 when its warm, which is correct I believe.
Originally Posted By: Virtuoso
^^^
First thing to check. After that, check for vacuum leaks.
Would vacuum leaks 'go away' when I shut off the car and restart it?
^^^
First thing to check. After that, check for vacuum leaks.
Would vacuum leaks 'go away' when I shut off the car and restart it?
I wouldn't generally think so. But it could jostle things up, just enough. If it were the case, a quick wiggle would hopefully find it.
Did the TPS get installed correctly?
I never had a TPS off any of my Saturns, but on some cars they are not fool proof and can be installed wrong, leading to definite issues with idle/performance.
Check to see if the TB is sticking as well, they do suffer from some carbon buildup those S-series. my SOHC (like yours) was worse than the DOHC's.
I never had a TPS off any of my Saturns, but on some cars they are not fool proof and can be installed wrong, leading to definite issues with idle/performance.
Check to see if the TB is sticking as well, they do suffer from some carbon buildup those S-series. my SOHC (like yours) was worse than the DOHC's.
When you start/ restart the ecm resets the .35 volts or whatever as "base/zero" then if it wiggles up or down it says you want 1% throttle, and it opens the ISC motor all the way for emissions/ dashpot duty.
I suspect since you got a new part that is presumably not scratchy, that something like another sensor is messing with your +5v reference from the computer, or a ground. Check for ANY voltage between pins 4 and 5 on the OBDII port; there should be none. One is computer ground, one body. Most scan tools short these two pins together; if your car runs great with a scan tool connected you have a ground discrepancy.
I suspect since you got a new part that is presumably not scratchy, that something like another sensor is messing with your +5v reference from the computer, or a ground. Check for ANY voltage between pins 4 and 5 on the OBDII port; there should be none. One is computer ground, one body. Most scan tools short these two pins together; if your car runs great with a scan tool connected you have a ground discrepancy.
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