Idle Air Control

[BRONCO_POWER]

When I connect my IAC my Bronco idles fine. The problem I'm having is when I'm shifting the RPM's stay up. When I come to a stop the engine idles back to normal. When I disconnect the IAC I don't have this problem.?:? What should I do?

 

[Viperwolf1]

What computer is it?

 

[BRONCO_POWER]

What computer is it?

I have a A9P.

 

[br0nc0xrapt0r]

Do you have VSS hooked up? what about clutch and brake switch? I'm just spit balling here off of my 95 monstrosity.

 

[Viperwolf1]

I have a A9P.

A9P is programmed to do that. A9L would be a better choice.

 

[BRONCO_POWER]

So should I just leave it disconnected? And if I leave it disconnected will I have any problems?

 

[Viperwolf1]

So should I just leave it disconnected and if I do that will I have any problems?

Either live with it, swap out computers or have your's reprogrammed. If you leave the IAC disconnected the computer won't be able to control the idle speed. You will have problems on cold starts.

 

[needabronco]

The A9P is for an automatic, thus why the rpms stay. You don't need a vss with this EEC either. The A9L for a manual needs the vss signal.

 

[BRONCO_POWER]

A9P is programmed to do that. A9L would be a better choice.

Is it a plug and drive swap?

 

[BRONCO_POWER]

The A9P is for an automatic, thus why the rpms stay. You don't need a vss with this EEC either. The A9L for a manual needs the vss signal.

VSS is connected.

 

[Broncobowsher]

If it runs fine with the IAC disconnected you probably have the minimum airflow set too high.

The rule I have been taught (and has worked for the past couple decades) is the engine should go to a low idle and stall in 2-5 seconds after unplugging the IAC. If it dies the moment you unplug it, the minimum airflow is too low. If it keeps running, the minimum airflow is set too high. This is for a fully warmed up engine in nuetral with no accessories running.

 

[Viperwolf1]

Is it a plug and drive swap?

One wiring change is needed to pin 30. If you have an RJM harness there is a swappable plug for this.

 

[70_Steve]

Either live with it, swap out computers or have your's reprogrammed.

Running an A9P. I just live with it. I pretend I have an automatic!

 

[BRONCO_POWER]

I'll be swapping out my computer in the near future. Thank you for your help.

 

[needabronco]

VSS can stay connected, its just not 100% necessary. I would just leave it as is.

 

[BRONCO_POWER]

VSS can stay connected, its just not 100% necessary. I would just leave it as is.

Will do.

 

[mattt]

If it runs fine with the IAC disconnected you probably have the minimum airflow set too high.

The rule I have been taught (and has worked for the past couple decades) is the engine should go to a low idle and stall in 2-5 seconds after unplugging the IAC. If it dies the moment you unplug it, the minimum airflow is too low. If it keeps running, the minimum airflow is set too high. This is for a fully warmed up engine in nuetral with no accessories running.

Minimum airflow set too high or low? How is that set.....throttle stop screw on bottom of tb? I've never heard that terminology used "minimum airflow setting..." so I thought I'd ask. TIA

 

[Sun_and_Steel77]

Minimum airflow set too high or low? How is that set.....throttle stop screw on bottom of tb? I've never heard that terminology used "minimum airflow setting..." so I thought I'd ask. TIA

X2 on the above...please elaborate on this airflow setting and how you adjust it.

 

[Broncobowsher]

Yes, the screw that holds the throttle open slightly. In the old carb days it would have been the idle speed screw. With EFI you set this lower then the engine can run and let the computer control the idle speed with the IAC. Too far closed and the throttle will tend to stick as the aluminum cools and shrinks to the throttle blade. Too far open and the computer can't control the low end of the idle speed.