Mechanics

HIGH IDLE THEN RPM BOTTOMS OUT

1995 Saturn SL1 • 4 cylinder 2WD Automatic • 101,000 miles

OK, so I have to hold down the gas to crank the car. Then it has a high idle (2k RPM) for about 15-30 Seconds then the idle hangs around 1100 RPM. After about 2 miles the check engine light comes on then goes back off once the vehicle has warmed up. After about 15 minutes of driving the RPMs will bottom out and while at a stoplight they will jump to 1400 RPM and bottom back out to 500. I've replaced the Idle Air Controller, Throttle positioning sensor, and PCV valve. The vehicle has only 101,000 miles on it with regular service doone it. This issue causes the vehicle to shift hard and not want to crank.
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Raustinesq
December 2, 2010.



You could have more then one problem but let's start with the problem of you have to hold the gas pedal down to start it. That is most likely a bad coolant temp sensor really common on those car's. There only like 10 it's screwed into your head over by where you upper radiator hose goes onto the head. It's the bottom sensor with two wire's going to it. Also inspect the connector going to it if it's corroded you will have to replace the connector too.I would start by replacing the sensor and see how it run's make sure you get a brass tipped sensor the plastic tipped one's crack and leak into the connector's. Let me know what you find and how it run's after you replace the sensor. Also what code's do you have?

Saturntech9
Dec 2, 2010.
Ok, i'll have to try that on Sunday. I appreciate it. I'll update you with a SITREP as soon as I have one. Don't have the codes.

Tiny
Raustinesq
Dec 3, 2010.
Alright keep me posted.

Saturntech9
Dec 3, 2010.
Awesome! Sorry it's taken so long to get back to you, but I just changed it today, and it solved the starting problem. I now dont think I have an idling issue either. I've realized it's a hesitation issue. It feels like it's bogged down between 1000 and 2500 RPM. Any thoughts?

Tiny
Raustinesq
Dec 13, 2010.
If it's a hesitation issue I would be checking your plug's and wire's and coil tower's for corrosion also check and make sure your spark plug wire's to make sure there routed correctly.

Saturntech9
Dec 14, 2010.
Subject: 95 saturn SL1

From: raustinesq reply
I appreciated the help and advice you gave me about my idling issue. It was a huge help. It cranks now with no issues after replacing the coolant temperature sensor. It seems now that instead of it having been an idling issue it's something else. I dont experience any fluctuation in the RPMs now. But it's accelerating very sluggishly between 1000 and 2500 RPM. Also, it will shift funny, either into the next gear too soon, or not into the next gear at all unless I let off the gas. Then it will shift up. To me it seems like a vaccum issue but I dont really know where to start. If you remember the original post I had already replaced the Idle air controller, the throttle positioning sensor, and PCV valve before you suggested the collant temp sensor. The check engine light stays on constantly now and I dont know if it makes a difference but the door chime continues after taking the keys out of the ignition (no head lights on or anything else).
Saturntech9 say's>You really need to reply on this question you started so I don't have to go to my email and copy and paste what you wrote to me there. So does your car feel like it has a lack of power?Because you say you have to let off the gas to shift that to me sound's like you could have a plugged cat. So what code's do you have you said you have your service engine soon light on.
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Saturntech9
Dec 15, 2010.

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