Newer (black) ISC coils testing 42.7-43 Ohms - how much over 40 ohms is bad?

[Gremo87]

http://www.dsmisc.com/dsmweb-dw/faqs.html says newer ISC's should test 40 +/- 0.25 ohms. Is the window really that small? Is 42-43 ohms indicative of a bad ISC?

 

[2gmitsueclipse]

That ISC should function just fine. I would be worried if it was too low.

 

[steve]

I wouldn't worry about that as long as the ISC is still stepping. Have you pulled it and verified that it homes the pintle at ECU power up?

 

[Gremo87]

Can you explain more Steve? I'm not sure what that means. I took the ISC off and turned the key to on and then checked the ISC and it wasn't doing anything.

It has maybe 2mm of rotational movement if I move it by hand.

PS. Car dies when both diagnostic and timing pins are grounded together, and has low vacuum at idle - and an unsteady idle - if that means anything to anyone - new thread here specifically asking about that: http://www.dsmtuners.com/threads/ca...-and-diagnostic-pins-are-grounded-why.495573/
(And I've done extensive boost leak testing! )

 

[2gmitsueclipse]

The stepper motor should move on its own when the ignition is turned on. Have you recently replaced the ISC? If so, what was wrong with it? How long have you had this one installed?

 

[Gremo87]

Nope I just bought the car recently and it already has a newer version black ISC on it.

So the pin should be moving in and out with the ignition on...well it definitely doesn't do that.

Just to make sure there's no misunderstanding - when you say pin, you mean the thing that protrudes into the hole where the ISC mounts right? The tower-looking thing that I can rotate just a teeny tiny bit?

That thing doesn't move with the ignition on.

Edit: Oh wait - do you mean it just moves once when the key is turned on and then it stops moving? Like in this video?

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Cause I didn't have another person helping me, so I just turned the ignition on and then walked back to the engine bay - I wouldn't have seen it move if this is the case.

 

[2gmitsueclipse]

It should be moving something like this:

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[2gmitsueclipse]

You have a couple of things to check now:

• Check the ISC driver on ECU:http://www.dsmlink.com/wiki/driver01?s=isc drivers

• Replace with a known working unit.

• Open it up to see if it needs cleaned out. See here for more info:http://www.stealth316.com/2-isc-iac.htm

 

[steve]

Edit: Oh wait - do you mean it just moves once when the key is turned on and then it stops moving? Like in this video?

Yes the pintle is the tip that moves. It shouldn't move much by hand but it should move like in the videos.

If it doesn't then it could be the ISC, ECU drivers, or the wiring harness.

 

[Gremo87]

Ok thanks guys I'll have to check it again for movement at the turn of the key rather than after.

 

[Nuzzi]

Any recommendations on which make of a replacement is best? There are several different manufacturers of this newer type. I had replaced my ISC about a year ago with a bpc type and at the time the coils measured about 33ohms, I knew it was low but had no choice to run it. It actually worked fine until recently, although the cel has been on the entire time. Time for another new one.

 

[Gremo87]

I've heard good things about www.dsmisc.com but I have no personal experience with them or any other.

 

[steve]

If I remember correctly RockAuto has them for less than $70.