Is there a way to test the IAC???

[Pronto]

What would the procedure be if you are replacing a properly adjusted tb/iac/tps with a ported tb with unknown idle screw adjustment? I would like to change my tb/doghouse and add a pp with the minimum issues. I assume I should warm the engine before taking off the tb/housing.

 

[turbo39151]

Tested both cars today. Best I could get was 45 on the IAC. Then we took a known working unit from his car and it was on the money with almost no adjustment. None of the special re-set steps were necessary...

So it seems both of my IAC's are inoperable... Now I'll replace them and have no more headache. At least that's the plan...

Thanks to everyone for the help...

 

[strikeeagle]

Glad you were able to run it down...

strike

 

[greeneyegi]

You did it all wrong.
First, unscrew and remove the IAC motor (ignition off) and clean the pintle, and also clean the pintle seat and holes in the throttle body. (the conical hole that the IAC pintle seals in). Use carb cleaner and wipe the pintle seat clean with a paper towel. Screw it back in, but dont over-tighten it cause you can crack the sealing gasket for the IAC. (is the gasket in there????)
Warm the engine up. Shut it off.
Turn the idle air screw in a few times to open the throttle blade a little.
Ignition on, short those 2 pins (top right 2 pins) and wait. Shut ignition off. Pull that paper clip AFTER ignition is off.
Pull the IAC connector.
Start the engine. Slowly turn the idle air screw out and keep bringing the idle down until the engine dies.
Turn the ignition OFF.
Plug the IAC CONNECTOR back in.
Now turn ignition on.
Adjust the TPS sensor to .44 volts at idle. Scanmaster makes it easy.
Tighten TPS down.
Shut ignition off.
Start engine.
Good to go.

What does it mean when the screw is all way out and no longer touching adjustment screw and car wont die?Nothing binding up the throttle body?

 

[NY Twin Turbo]

What does it mean when the screw is all way out and no longer touching adjustment screw and car wont die?Nothing binding up the throttle body?

It means the ECM is commanding the IAC to open as much as necessary to keep the engine idling. Or it means the IAC is stuck open. Or it means you have a vacuum leak. Or it means air is escaping past the IAC for some reason, like crud holding it open.

But basically, it means something is wrong. Because if the engine is running and the throttle is closed 100%, the engine is getting air from somewhere.

Most likely, the first thing I wrote. Adjust according to the procedures outlined by other posters to this thread.

 

[GNRick]

I've had a couple high iac issues on two different tr's over the years. Both were solved by cleaning the throttle body where the up pipe connects and where the IAC screws in. Also cleaned the carbon off the IAC. Never did that grounding/resetting procedure.

 

[greeneyegi]

That

It means the ECM is commanding the IAC to open as much as necessary to keep the engine idling. Or it means the IAC is stuck open. Or it means you have a vacuum leak. Or it means air is escaping past the IAC for some reason, like crud holding it open.

But basically, it means something is wrong. Because if the engine is running and the throttle is closed 100%, the engine is getting air from somewhere.

Most likely, the first thing I wrote. Adjust according to the procedures outlined by other posters to this thread.

thanks,
Yeah i followed the instructions to where you unplug the iac then bring idle down to shutting off but it didnt,so today i will dig into it some more.

 

[greeneyegi]

by shorting the aldl ,is this causing the iac to extend fully?
In theory the iac extended with the throttle blade closed,zero air should be entering plenum?