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1G Idle Speed Control not Good !!

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emanuele

Probationary Member
9
0
Aug 15, 2009
C.del Lago, Europe
Hi,
I have a problen with Idle speed control in My 1G Eclipse Turbo AWD 1991.

I would like to be have a help about my problem:
When my car is running at the idling occurs that the number of revolutions of the engine vary intermittently between the value of 1500 rpm and 1800rpm.
I tried to replace my old ISC Motor with a used plastic but the problem remains.
 
Without the FIAV you shouldn't have much of a fast warmup idle. Since the ECU programmed idle and decel cutoff limits are higher when the ECT is low to allow the FIAV to fast idle your not hitting the decel cutoff when cold. As the coolant temps rise the values in the table drop just like the idle speed is expected to and at some point your crossing the line and surging starts.


Does your ISC pintle move in and out when you turn the ECU on like in this video? If it doesn't then the ISC system is not working correctly.

Does the IPS have a good ground connection and pull the voltage on the green wire to 0 when the throttle is closed and sit at > 5v when the throttle is opened. If it doesn't the IPS isn't working correctly.

Do all four coils in the ISC measure between 28 and 38 ohms? If not the ISC is bad, it can still be bad if they do since this only tests the coil windings and not the bearings or pintle screw thread.

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If the ISC works you have a bypass leak somewhere. They are harder to find since a pressure test only identifies external leaks so you may still have air sources to the intake after you have found all the external "boost" leaks.

No, the ISC pintle doesn't move like that video with the ignition turned on and off. It doesn't move whatsoever. I hear a single click and feel it click in my hand, but no movement or vibration.

I adjusted the IPS. Throttle cable disconnected, unscrewed the IPS then screwed it in until I got continuity...then screwed it in 15/16 of a turn more. This is how I was always told to do it.

I will check the voltage when I get home from work tonight. I am not sure how many volts is going through the green wire. The thing I do know is that if I unplug the connector from the IPS, the idle will remain at a constant 1500rpm without any surge...so I assume it is working properly.

The coils measured at 38 ohms across each one. I tested it three times just to make sure. I have an old tan colored one sitting in the garage that I tested and it tested out at 28 ohms...I am not using the tan one. I am using the newer black plastic one.

I have the small grounding tab on the throttlebody still, if that's what you're talking about.
 
I bought a brand new ISC and decided to test the current one again before putting the new one in.

When the ignition was turned on and off, the plunger moved in and out.

The initial testing resulted in the ISC simply clicking a single time and nothing else happened. I connected the brand new ISC and the plunger moved the same amount in and out as my current ISC. So the thing here that I should ask is this, is the current ISC still good since the plunger moved freely when the ignition was cycled?

Because as I said, the last time I checked, the plunger did not move and it clicked one time and that was it. If this ISC, I am going to return this brand new one.
 
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