IAC not right!

[Hu Ryde]

Truck is running pretty rough, hook it up to DM and notice that my IAC position was like 60 or so. So I think to myself I have a major vac leak somewhere. I hook the bike tube up to cac and run some air through it. nothing leaks but the TB bushing a very little bit. Well that's pretty normal so I think to myself what next? First I think what caused this??? I just rebuilt the top end about 2 weeks ago and I have about 120 miles on the truck and now this after the rocker situation. do the iacs go bad often?? What indicates a iac that has gone bad?

 

[leroy]

IAC counts would be low with a vacuum leak. Maybe you have a miss and the IAC is compensating to maintain the correct idle speed.

Jim

 

[Hu Ryde]

Shouldnt the IAC be closed or at a low number when running? Anyway I pulled the IAC out of the TB and it is froze, wont move a bit! Going to get a new one and hope that helps.

 

[Loeryder]

The IAC is like a stepper motor. So i am not sure if you'd be able to move it by hand, try applying a voltage...

It steps or "counts" in either direction to let more or less air into the TB while idling. Really doesn't do anything any other time than idling.

Now that you have it out, plug it into the harness and turn on the key measure how far the pintle sticks out.
Turn it off and remeasure.

I have the specs and procedure at home I can email you when i get there, but this should tell you if it is working at all.

FWIW I have seen most trucks idle around 14-15 counts.
Mine is 10 right now, but the vac check valve in the AC controls is hissing.
So with a slight leak it drops counts.
Gotta fix dat.