50ohms on IAC coil?

[eagle93]

I have searched and found many resons for a sparatic idle but none answer my question. When im driving the vehicle everything is fine but when im stoped with the clutch in the idle is boumcy.(900-1200rpm) Then it slowly settles down to 8-900rpm. I tested the coils in the IAT and the first one is at 50ohms where the other 3 are at 30. Would this be enough to make the iat twitch? Im sure there are no vacuum leaks and will make sure tomrrow but was wondering if 50ohms is whats causing the problem.Thanks in advance. Also spec says 28-33ohms in the chrylser service manual.Thanks

 

[snowborder714]

Yes, if one coil is way out, then the ISC is bad. Although I have never seen one coil be higher - it's usually dead (0).

 

[eagle93]

yea thats what I was thinking too. I was looking for maybe 1-2k ohms. Is there anything else besides checking for vacuum leaks that you recommend? thanks

 

[snowborder714]

I'd start with those two and see how that goes.

 

[hotrodssnova]

Those coils should check out at 30 ohms. I had 4 bad iac motors and every one of them had 1 coil at 50 or above and the other coils check in at 30 on the nose. Bought a brand new one and all the coils tested at 30 ohms. The book says to replace the iac if it tests higher then 30 ohms. Btw, each of my bad ones, it was either the first set of pins or the last set, never the middle ones.
Iac= idle air control?
Isc= idle speed control?
I assume we are talking about the stepper motor on the bottom of the tb.
Also they are the same between the Turbo and non Turbo.

 

[eagle93]

Ok thanks guys. Im going to the slvage yard today(day off). Only yard in the area with 4 1G cars. Ill test the coils right on the car

Today I found another Iac stepper motor at the salvage yard. on the last set of pins there was very high resistance(miliohms). So that one was bad too.So now the search is on. I was able to find the door trim peices that go on the top edge of the door beneath the window. Usually the platic coating cracks up. Are stepper motors known problem with 4g63 motors?

 

[Jkappa]

I think so, because I'm going through it now on a 2g.

appreciate when someone offers you help, you may have to buy a part from him in the future!

 

[snowborder714]

Iac= idle air control?
Isc= idle speed control?
I assume we are talking about the stepper motor on the bottom of the tb.
Also they are the same between the Turbo and non Turbo.

Yes, same piece, just different names.
There are a few different units for the 1g's (not sure what some of the 1.8l engines had or what some of the N/T 2.0l engines had), but the 2g N/T units are not the same.

Are stepper motors known problem with 4g63 motors?

Yes, there are a part that goes bad somewhat often.

 

[eagle93]

OK so here is a update. I bought a new ISC and I still have the problem. Theres a new intake gasket and tb gasket installed. I checked for vacuum leaks but have foiund none and even sprayed around with intake cleaner and the idle doesnt change. Also cleaned and checked the EGR and its working great. BISS screw is good and TB is clean.But it still jumps between 700-1500rpm at stop lights ,only jumps when the engine is warm. (about 2min running) and settles down to normal idle speed after about 10sec. Any ideas?

It has to be something telling the ecu to move the isc in and out constantly.