Mechanics

HIGH IDLE

1995 Saturn SC1

Engine Performance problem
1995 Saturn SC1 4 cyl Front Wheel Drive Manual 298600 miles

My Saturn idles between 1500 and 2000 rpm while the car is in motion. When I come to a stop it will quickly fall to a normal idle and remain until the car is put back into motion. The car runs great with no sputter or stalling. I have replaced both the IAC and the TPS with no luck. Could a break sensor be involved with this problem? Please help
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Kmk1
February 11, 2010.



Well when ur at a stop that would be considered idle not while ur in motion. The computer knows when ur in motion how fast ur going etc.U have a stick so the rpms are higher if they went quickly down to idle rpm when u went to shift to a higher gear that wouldnt be good. Then the engine would be fighting to catch up to the next gear. Do u have any codes?Does that make sense to u?

Saturntech9
Feb 11, 2010.
Yes that does make sense. But when I put it in nutrual at a slow roll 5 to 10 mph or so it revs up to 2 grand. The weird thing if I unhook the battery for a few minutes the problem completely goes away for about a week of
driving then the high idle comes back slowly. I mean the car has almost 300 thousand and is all original except the IAC and the TPS I just replaced tryin to
solve this idle problem, and the water pump. There must be a sensor making this happen. If it were a vacuum leak it would idle high whether stopped or not. Thanks for
your reply.

Tiny
Kmk1
Feb 12, 2010.
If u have had the car the entire time for 300,000 miles and thats all u changed then u reallly need to check ur coolant temp sensor. That will make the car all kinds of crazy stuff even effect the idle. Its screwed into the head below where the upper hose goes on. It has two wires going to it a black wire and a yellow wire. Check the connector too they get get corroded if its corroded u will have to clean it replace it. They crack the tip and leak coolant into the connector. If u replace it get a brass one the plastic tip ones crack. There under 20 let me know what u find.

Saturntech9
Feb 12, 2010.
Yes the car has been in my family since brand new, pretty amazing it runs as good as it does with that many miles and even has the original clutch! I'm goin to go pull the sensor an check it out. Thank u very much for your feedback I really appriciate it. I will post my findings. -Mike

Tiny
Kmk1
Feb 12, 2010.
Well I pulled that sensor and it was cracked. Replaced it with a new one with a brass tip and nothing changed. I found this sensor is not the one that controls the temp gauge. The sensor directly below the coolant hose with one wire to it is the one that controls the temp gauge. I pulled it out and it has the brass tip. Is this the sensor I should have changed? The temp
runs very low also, it runs less than half way to the first mark on the gauge. Is this normal? Thanks. -Mike

Tiny
Kmk1
Feb 12, 2010.
[quote=" Kmk1" ]Well I pulled that sensor and it was cracked. Replaced it with a new one with a brass tip and nothing changed. I found this sensor is not the one that controls the temp gauge. The sensor directly below the coolant hose with one wire to it is the one that controls the temp gauge. I pulled it out and it has the brass tip. Is this the sensor I should have changed? The temp
runs very low also, it runs less than half way to the first mark on the gauge. Is this normal? Thanks. -Mike[/quote
u changed the right one and it was bad if it was cracked. If ur car runs that low and its not super cold out u ethier have a bad thermostate, temp gauge or ur temp gauge sender the one with one wire. But with all those miles and u havent changed much then I would say it wouldnt hurt to repalce the thermostate. Let me know how it runs after that.

Saturntech9
Feb 12, 2010.