mtskowronski Posted April 16, 2008 Report Share Posted April 16, 2008 I have a 1993 Cadillac STS and it is periodically revving to 2-3,000 RPMs. There isn't a pattern to it - it happens when I put it in park or when I come to a stop. It makes the car lurch forward and drive so I have to keep on the brake until it stops revving. Anyone know what's causing this?? Link to comment Share on other sites More sharing options...
abad95 Posted April 16, 2008 Report Share Posted April 16, 2008 That would be the ISC (Idle Speed control) Motor. Florin Link to comment Share on other sites More sharing options...
mtskowronski Posted April 23, 2008 Author Report Share Posted April 23, 2008 That would be the ISC (Idle Speed control) Motor. Florin Link to comment Share on other sites More sharing options...
jackc Posted April 23, 2008 Report Share Posted April 23, 2008 That would be the ISC (Idle Speed control) Motor. Yep. Its time to replace it. An AC Delco replacement can be had for about $65. Git 'R Done before you burn your brakes or launch it into a wall. Link to comment Share on other sites More sharing options...
fivepointohman Posted April 23, 2008 Report Share Posted April 23, 2008 That would be the ISC (Idle Speed control) Motor. Yep. Its time to replace it. An AC Delco replacement can be had for about $65. Git 'R Done before you burn your brakes or launch it into a wall. Welcome to my world my friend, It's actually not the IAC motor... I have replaced it about a dozen times to date so far. First thing you need to do is check the car for codes. It is most likely a wiring issue as many of us experience this. Mine will do this without warning at random times and I cannot stess enough that this behaviour is bad for the transmission. let me know if you need additional help. Link to comment Share on other sites More sharing options...
jackc Posted April 23, 2008 Report Share Posted April 23, 2008 Welcome to my world my friend, It's actually not the IAC motor... Year models 96 and up do not have ISC motors. They use an Idle Air Control, which is a different system. I'd support doing additional diagnostics, but on a 93 model the most likely cause of random revving will be a bad ISC motor. Link to comment Share on other sites More sharing options...
fivepointohman Posted April 23, 2008 Report Share Posted April 23, 2008 Welcome to my world my friend, It's actually not the IAC motor... Year models 96 and up do not have ISC motors. They use an Idle Air Control, which is a different system. I'd support doing additional diagnostics, but on a 93 model the most likely cause of random revving will be a bad ISC motor. The 93 still has a Idle motor. I would dig into it deeper with some diagnostics before replacing it. Link to comment Share on other sites More sharing options...
mtskowronski Posted May 6, 2008 Author Report Share Posted May 6, 2008 Thanks for the help, I'll look into these suggestions. The car's just been sitting in the driveway cuz I don't want to kill the brakes and tranny. I did name the car Christine though!!!! for those of you who are Stephen King fans! Link to comment Share on other sites More sharing options...
abad95 Posted May 6, 2008 Report Share Posted May 6, 2008 Have your ISC motor changed. It won't hurt.Sooner or later you will have to. Florin Link to comment Share on other sites More sharing options...
hiljak Posted May 12, 2008 Report Share Posted May 12, 2008 Have your ISC motor changed. It won't hurt.Sooner or later you will have to. Florin check the throttle body and blade for build and clean it well. Sometimes a buildup and make the idle control motor max out and skip. If it still does it after you clean the blade and throttle body, change the ICM. James 1999 STS 65k 1995 STS 127k Link to comment Share on other sites More sharing options...
iwanta2000caddy Posted May 12, 2008 Report Share Posted May 12, 2008 Have your ISC motor changed. It won't hurt.Sooner or later you will have to. Florin check the throttle body and blade for build and clean it well. Sometimes a buildup and make the idle control motor max out and skip. If it still does it after you clean the blade and throttle body, change the ICM. i have a 2000 STS and had the EXACT same problem. REALLY ANNOYING! it turned out to be the crank shaft sensors ($300 incl parts and install from the dealer)_.. PCM 341 or 340 i think. Anyways, i am not sure if this is the same problem with your car but definately worth looking into cheers Link to comment Share on other sites More sharing options...
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