More ISC Headaches...

[higaran]

Let's start with some history:

I have a 1G Laser 2.0 Turbo AWD 5-spd. Last January, I started having the classic DSM idle surge problems. Knowing nothing about these problems, I took the car to a local grease monkey, who eventually figured out that my idle speed control motor was fried. He told me that a replacement from Chrysler would be nearly $600 CAD. Not wanting to spend that much money, I asked him to just disconnect the motor so I could drive without it. I also took the car to another shop for a second opinion, and they confirmed that my ISC was really dead.

So for the last 10 months, I've been driving with no ISC. It actually works OK, but you've got to stomp on the pedal when you want to start the engine cold, and you've got to keep a feather-weight on the pedal when your A/C is running to keep it from stalling out.

Anyhow, in November I discovered a guy on eBay who rebuilts DSM ISCs, and I bought one from him for about $40 US - not a bad deal, I thought.

So yesterday, I removed the old ISC from my car and installed the new one. But there's no difference in the way the engine operates! I still need to stomp on the gas to get the motor started, or it stalls the moment you stop cranking. I tried both the old and the new ISCs with the same results - no difference.

I even tried hooking up the wiring harness to the ISC and just holding it in my hand while I had someone else crank the motor and start the car. When you're holding the ISC and you turn the car's ignition on, you can feel a brief "twitch" in your hand - something is happening inside it - but you can't see the shaft move at all. Both the old and new ISCs seem to do exactly the same thing.

Is this the way the ISC is supposed to operate? I'm pretty hamfisted mechanically, so I really know next-to-nothing about what I'm doing. How do you know if the ISC is working or not?

Did the eBay guy sell me a dud? Or is there really something entirely different wrong with the car?

I hope someone can help me out!

 

[SoonToBeDSM06]

Let's start with some history:

I have a 1G Laser 2.0 Turbo AWD 5-spd. Last January, I started having the classic DSM idle surge problems. Knowing nothing about these problems, I took the car to a local grease monkey, who eventually figured out that my idle speed control motor was fried. He told me that a replacement from Chrysler would be nearly $600 CAD. Not wanting to spend that much money, I asked him to just disconnect the motor so I could drive without it. I also took the car to another shop for a second opinion, and they confirmed that my ISC was really dead.

So for the last 10 months, I've been driving with no ISC. It actually works OK, but you've got to stomp on the pedal when you want to start the engine cold, and you've got to keep a feather-weight on the pedal when your A/C is running to keep it from stalling out.

Anyhow, in November I discovered a guy on eBay who rebuilts DSM ISCs, and I bought one from him for about $40 US - not a bad deal, I thought.

So yesterday, I removed the old ISC from my car and installed the new one. But there's no difference in the way the engine operates! I still need to stomp on the gas to get the motor started, or it stalls the moment you stop cranking. I tried both the old and the new ISCs with the same results - no difference.

I even tried hooking up the wiring harness to the ISC and just holding it in my hand while I had someone else crank the motor and start the car. When you're holding the ISC and you turn the car's ignition on, you can feel a brief "twitch" in your hand - something is happening inside it - but you can't see the shaft move at all. Both the old and new ISCs seem to do exactly the same thing.

Is this the way the ISC is supposed to operate? I'm pretty hamfisted mechanically, so I really know next-to-nothing about what I'm doing. How do you know if the ISC is working or not?

Did the eBay guy sell me a dud? Or is there really something entirely different wrong with the car?

I hope someone can help me out!

Since you have idle surge, have you checked for common vac leaks and pressurized the system? You can check the ISC motor to see if it works by yourself if you have a ohmmeter or a multimeter by going here

 

[turbo2086]

Check out your FIAV (fast idle air valve) That is actually used when you first start the car cold. It opens and closes by the coolant temp. Perhaps its stuck open, or close.

Boost leak test. See if your O ring for your Biss is leaking, or your shaft seals.

Adjust your idle by grounding terminal #10 in your diagnostis port, and grounding the wire behind the battery coming from the firewall. Do this when the car is warm. Then adjust your idle. Its in the Haynes/Chilton manuals.

Do you have a datalogger?

 

[BaddAssGst]

You can measure the resistance between the coils on the ISC. You measure resistance between 1 and 2 and 2 and 3 and then check them from 4 to 5 and 5 to 6. The resistance should be somewhere between 28 and 33 ohms.

Also, how often does it surge when it's connected? When it's warm, when it's cold, all the time?

 

[higaran]

Thanks - I will check the ISC terminals with an ohmeter - that's probably the place to start.

The car no longer surges. It started surging about this time last year, only when the motor was warm - say, after I'd pulled into a parking lot after driving on the highway for an hour. But after I unplugged the ISC, of course, the surging stopped. I tried reconnecting it several weeks later, but it no longer surged at all. It also no longer revved the engine up when I started the car cold, which led me to believe that the ISC was responsible for both.

I never knew anything about a fast idle valve. Where is it located? Sounds like that's more likely to make the motor stall when I try to start it cold.

I also never knew I could adjust my idle, but I do have a Haynes manual, so I'll have to read up on that. The car usually starts OK in the summer, but when it hits -40 degrees here in Canada, it's hard to start the car at all somtimes.