Idle Air Control Motor

[JonJames_dsm]

How would the engine operate if there was some damage to the IAC or if it had a loose connection?

 

[shorty10011010]

it really depends on how damaged it it. but typically it would have idle surge, even a possible boost leak

 

[My1GLaser]

The idle rpm is based on how much air bypasses the throttle plate when closed. (assuming closed loop functions are working correctly and fuel supply is correct)

1. The throttle plate doesn't seal completely tight so some air bypasses it when closed.

2. The BISS allows a certain amount of air to bypass the plate.

3. The FIAV allows air to bypass when the car isn't at operating temp. (or anytime because it sucks! )

4. Depending on where the ISC was when it stopped moving, it is allowing air to bypass also.

What you don't have now is something to control the idle when there is a load (ac, fans, etc) when coming to a stop and the rpms drops rapidly, or if there is too much air bypassing the throttle plate.

You can change the idle with the BISS if it is revving high from too much air or stalling out because of too little. Turn it in to reduce the idle (clockwise) turn it out to increase the idle (counterclockwise).

 

[bertrenolds]

I would also like to add that a defective IACM can also burn you ECU board out, happened to me. If you are worried it's bad autozone has them for under a $100 brand spanking new. And it causes idle surge and your car will never sit at a certin rpm. It's main use if for keeping your car running smooth until your car is warm and I know people that run without them but IMO it is way less of a bi*** to get your car started by keeping it. Get a block off plate for everything else but keep the IACM.

 

[boost97gst]

Ring the ISC motor as follows: Pin 2-3, pin 1-2 Pin 5-6, Pin 5-4. All should read roughly 30 ohms

 

[bertrenolds]

Ring the ISC motor as follows: Pin 2-3, pin 1-2 Pin 5-6, Pin 5-4. All should read roughly 30 ohms

That test is unreliable because you can have it read 30ohms accross the board and have it still not work. You are supposed to test it under power somehow and no one has the tools. If you suspect its the IACM and yours it the old ass brown top or even a worn looking black one I would just replace it. Make sure you don't have an boost leaks and then it's probably the FIAV or the correct name IACM. They are so cheap now at autozone it's worth the piece of mind!