IAC operation?

[jph331]

The IAC on my car seems to be operating inproperly. Once it warms up the idle jumps to 1700-1900rpm. I try to adjust the idle speed vs coolant temp but no effect.

I unbolt the IAC from throttle body and adjust idle vs coolant temp to both extremes but iac position does not change. Also I cycle the key but iac does not move. Sometimes it will shake a little but nothing.

I tried my IAC and fast on another vehicle and it works fine. Also ohm checked the wires and it checked out good.

TPS is set to 13. The target rate would not change from 10 while adjusting idle screw until the vehicle died, then it jumped to 71.

What am I missing or not checking? Vaccum leak maybe?

 

[T66Typhoon]

On the typhoon, I had to adjust the throttle plates to get to work correctly.. you probably have to do the same. I could not get it to idle down enough and idle correctly because the IAC was so far out of it operating range... I had to open the throttle blades up a bit... a 1/4 to 1/2 a turn was all it took.

I just adjusted it until it was in range of the maps... where IAC was effecting it. Not sure if it makes sense or not what I am describing.. but try opening it up a bit and give your IAC some range to work with.

 

[bobc455]

I'm also gonna guess that the throttle blade(s) need to be adjusted. When the engine is cold it requires more air to idle, but when it warms up it idles with less air so I'm guessing that you need to close the throttle blade with the setscrew.

If the target IAC is not moving from 10 and you verified it's operation on another vehicle, then your high idle is probably due to too much air getting in somewhere else (a vacuum leak is possible too!). If that air is getting in through the throttle blades, closing it up a bit should help your problem.

-Bob Cunningham
bobc@gnttype.org

 

[Glen]

We are going to make afew assumtions first. Maximum TPS for Idle is set roughly 2 degrees ABOVE actual, meaning throttle resting on stop TPS reads 12* set max idle TPS to 14*. Throttle follower is set properly. No vacuum leaks

Either manually or electrically extend IAC pintle. Manually, remove IAC and extend pintle GENTLY by hand, doing it electrically depends on which style IAC you have, check your wire diagram to extend pintle. Reinstall IAC if removed, LEAVE electrical connecter DISCONNECTED, open throttle blade with throttle stop screw. Start engine and allow to warm up to operating temp. Adjust stop screw to 100 RPM BELOW desired idle speed, this is MINIMIUM idle speed. Shut off engine, reconnect electrical connector. Adjust idle maps ie. Idle Speed Vs Coolant Temp, Start IAC, Throttle Follower, Max TPS for Idle. Now. go smoke some Fords