1G Idle surge stops when AC is turned on

[surel0ser]

I read the post on adjusting the throttle cable because it hot conditions it sticks. When the ac is off the car idles when stopped but as soon as I turn the ac on the idle stops. Could this solve my problem?

 

[95blackGsTurbo]

So you are saying that when you turn your AC on your car stops idle surge? If that is the case it stops because the engine has a load on it and it means that you IAC motor is bad. Adjusting the throttle cable really wouldn't help anything unless there is uber slack in it or it's too tight. Check the voltage output on your IAC.

 

[surel0ser]

So you are saying that when you turn your AC on your car stops idle surge? If that is the case it stops because the engine has a load on it and it means that you IAC motor is bad. Adjusting the throttle cable really wouldn't help anything unless there is uber slack in it or it's too tight. Check the voltage output on your IAC.

Yep will do, whats an IAC?

 

[95blackGsTurbo]

Idle air control. Sometimes called ISC. Idle speed control. Basically it controls speed at idle.

 

[steve]

I've read many of the idle surge posts and it sounds like you have most of the answers. As I am a complete idiot when it comes to cars I enjoy mine and want to fix this idle problem. When I start the car the car idles between 1.5 and 2.5 rpms. But as soon as I turn on the ac the idle stops but will do it every once in a while when stopped for a brief time. I've read that the isc could be bad and to adjust the throttle cable. I found a picture of how to adjust the cable, I can do that. But I have no clue what an isc is. Sorry to both you just wanna get this problem fixed.

This might help you understand some of how this works. Ignore that it's for the 3000GT and stealth. They share the same setup.

http://www.stealth316.com/2-isc-iac.htm

Steve

I kind of understand but if the idle surge stops when I turn the ac on doesn't that mean the isc is functioning properly?

No. It doesn't mean anything. Does the idle drop when you turn on the AC? Does it go up and then drop back down to 750 when you turn the AC off?

Steve

When the ac is off the idle continues to surge from 1.5 to 2.5 rpms when the air is on the idle evens out at 1 rpm. When the air is turned off it goes right back idleing from 1.5 to 2.5

Then it's clear that your ISC isn't working. Start by checking the resistance of the ISC coils and check the ECU for blown ISC drivers and capacitor leakage. Once the ISC is functioning if you still have idle surge, check for boost leaks.

Steve

 

[steve]

Sometimes called ISC.

Depends are if you started as a 1G or 2G guy. They are called ISC in the 1G manuals and IAC in the 2G manuals. Same part, same function.

Steve

 

[surel0ser]

Then it's clear that your ISC isn't working. Start by checking the resistance of the ISC coils and check the ECU for blown ISC drivers and capacitor leakage. Once the ISC is functioning if you still have idle surge, check for boost leaks.

Steve

As I have no clue what any of those are or what to look for I will take it to a local shop and have them test everything. I am doubtful that I can find a good import shop in the area but I'll see what I can come up with. Thanks for all the help. I'll let you know what they find.

Also, I'm taking it alot of the 1gs have problems with the isc. Should I order a new or rebuilt one from one of the recommended shops or do you think a used one off a junker would work.

 

[surel0ser]

Just now had the time to get around to this can someone please tell me where this isc is located.

 

[steve]

Bottom left of the throttle body when your standing at the passenger side fender looking at the TB. In addition to the Stealth316 link there is some pictures of it's location on a DSM on http://dmtalon.v8eaters.com/ISC.html

Steve