IAC testing
 

I read in a previous post that while the engine is idling, unplug the IAC. if the engine idle drops, that means the computer and IAC are working together and there is no vacuum leak.
BUT, what if when you unplug the IAC at idle and the car dies??? Does that indicate the idle is set too low? And idle should be set with the IAC disconnected, right?
thanks in advance...

Use the feeler gauge method to set your idle:

Put transmission in park.

Back out the throttle screw.

Put a .010" feeler gauge between the screw and the throttle plate. Turn the screw in until the feeler gauge has a little drag to pull it out. With the gauge out, turn the screw another 1.5 turns.

Reset the computer by disconnecting the battery for 5 minutes.

Start engine and let it idle for 2 minutes. Goose throttle and let it idle. Then lightly press and release throttle. Let it idle for 5 more minutes.

Shut down engine.

Start engine and turn on all accesseries. Let idle for another 10 minutes.

Your idle should be what it says on your emissions sticker. About 650 to 700 rpms. Use a digital tach in multimeter to get RPM, not the one on your dash.

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351W 89 Mustang GT Convertible

Oh, forgot. Since something changes when you unplug the IAC it probably means it is working correctly.

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351W 89 Mustang GT Convertible

Thanks again Jim...I actually found that old post on how to do that, did it, and I think the idle is a lot better.