lothos Posted September 9, 2008 Report Share Posted September 9, 2008 I replaced my ISC last week with a brand new ACDelco part. I've noticed it still hunts for idle every couple days, and can see the gas pedal move. Is that normal behavior for these, or should I request a replacement part? When I replaced it I took out the old part, and put in the new ISC. I tried gapping the actuator so that there was a slight gap between that and the throttle lever. Went through the ISC testing tree in the book and it told me it was out of range, and to adjust the actuator out. So I moved it out and retested until it was at 10.5 degrees, which is within the 10 - 11 the book specifies. The throttle is being held open slightly by the ISC actuator now, at I assume 10.5 degrees open. I did the idle learn procedure. Every couple days now I can see the pedal move slightly, and I think the ISC might be hunting for an idle?? The ISC motor isn't loud like the old one, and the pedal doesn't move as much as it did when the old motor was in. So, should I request a replacement part, or is this normal? Thanks guys! WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn. Cheers! 5% discount code at RockAuto.com - click here for your discount! Link to comment Share on other sites More sharing options...
Ranger Posted September 10, 2008 Report Share Posted September 10, 2008 First be sure that you don't have any vacuum leaks. Link to comment Share on other sites More sharing options...
lothos Posted September 10, 2008 Author Report Share Posted September 10, 2008 If I look for vacuum leaks it sounds like I can use throttle body cleaner or Brake Kleen, is that right? I've found bits of information on vacuum leaks in threads here and there, but no step-by-step process that a newbie could follow. I'm pretty confident the ISC was adjusted correctly. I just ran out and checked my RPM using PCM Data PD11 and I'm sitting at around 650 on idle. It fluctuates a little bit between 625, 650 and 675. I'm not sure if that's high or not, if it was high that would indicate a vacuum leak right? WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn. Cheers! 5% discount code at RockAuto.com - click here for your discount! Link to comment Share on other sites More sharing options...
Ranger Posted September 11, 2008 Report Share Posted September 11, 2008 I think the amount of fluctuation would depend on how bad the leak is. Yes, Tb cleaner or Brakleen will work just fine. Spray it anywhere there is a vacuum seal (manifold mount, TB mount, vacuum hoses, manifold overpressure relief valve, etc and listen for an RPM rise. Link to comment Share on other sites More sharing options...
lothos Posted September 11, 2008 Author Report Share Posted September 11, 2008 Do my RMPs sound like it's where it should be? Should they be pretty solid or is it normal for them to fluctuate? Is it safe to use TB Cleaner or are there areas I should be careful with? I'll check for a leak tonight as soon as I find out I won't blow anything up Going through an automated car wash makes my RPMs fluctuate and the idle gets real rough. Also, this morning on the way to work it was raining, and my tires were spraying water, and the car ran rough. It didn't just happen at idle, it happened during driving so there's something else going on besides just the ISC (which only kicks on when the gas pedal isn't pushed). After turning off the car when I got to work, the iSC motor was hunting for an idle again when it hadn't done it for a couple days. From reading posts on here I've come to the conclusion that I need a new tensioner and serpentine belt and that it's probably slipping. WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn. Cheers! 5% discount code at RockAuto.com - click here for your discount! Link to comment Share on other sites More sharing options...
Ranger Posted September 12, 2008 Report Share Posted September 12, 2008 Do my RMPs sound like it's where it should be? Should they be pretty solid or is it normal for them to fluctuate? Your RPM's sound about right, but the hunting is not normal. Is it safe to use TB Cleaner or are there areas I should be careful with? I'll check for a leak tonight as soon as I find out I won't blow anything up TB cleaner should be safe to use. Going through an automated car wash makes my RPMs fluctuate and the idle gets real rough. Also, this morning on the way to work it was raining, and my tires were spraying water, and the car ran rough. It didn't just happen at idle, it happened during driving so there's something else going on besides just the ISC (which only kicks on when the gas pedal isn't pushed). Sounds like you have a moisture problem. Maybe a bad ground somewhere that gets wet. After turning off the car when I got to work, the iSC motor was hunting for an idle again when it hadn't done it for a couple days. Ratcheting after shutdown is generally a sign of a bad ISC motor. Link to comment Share on other sites More sharing options...
lothos Posted September 12, 2008 Author Report Share Posted September 12, 2008 Your RPM's sound about right, but the hunting is not normal. TB cleaner should be safe to use. Sounds like you have a moisture problem. Maybe a bad ground somewhere that gets wet. Ratcheting after shutdown is generally a sign of a bad ISC motor. So the RPM's should hold steady, and the fluctuating RPM is probably caused by a vacuum leak? I'll check that out this weekend. I called RockAuto and they're sending out a warranty replacement for the ISC. How do I look for a bad ground? Spray water until the problem comes back? What would the fix for that be? I'm pretty sure I need a new tensioner, pretty sure the belt slips under high acceleration. If the belt slips when wet could that be causing this problem? Thanks for your help, Ranger. WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn. Cheers! 5% discount code at RockAuto.com - click here for your discount! Link to comment Share on other sites More sharing options...
Ranger Posted September 13, 2008 Report Share Posted September 13, 2008 I think for the ground, you;ll need a FSM to locate them. If you find one that looks rusty or corroded, remove it and wire brush the contact surfaces till they are clean. I doubt that a slipping belt would cause a hunting idle. Link to comment Share on other sites More sharing options...
lothos Posted September 13, 2008 Author Report Share Posted September 13, 2008 I've got the FSM, and I've cleaned the grounds on the engine and the one by the headlight/battery. Haven't cleaned the one by the transmission/wheel well yet. How do I find the locations of the ground in the FSM? Any idea what section I'd need to look in? WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn. Cheers! 5% discount code at RockAuto.com - click here for your discount! Link to comment Share on other sites More sharing options...
Ranger Posted September 14, 2008 Report Share Posted September 14, 2008 Oh boy. now you're trying to test my memory. I know I've seen it. Somewhere in the electrical section if I remember correctly. Link to comment Share on other sites More sharing options...
lothos Posted September 14, 2008 Author Report Share Posted September 14, 2008 Haha ok, I'll take a look at it and see what I can find. Thank you very much for your assistance! WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn. Cheers! 5% discount code at RockAuto.com - click here for your discount! Link to comment Share on other sites More sharing options...
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