How do you tune in your IAC to work properly. I don't think mine is exactly right. I have a vortec headed 355 TBI. It runs great but I have the idle set way too fast to keep it running at stop lights.

 

are you adjusting minimum idle correctly?
zero out the iac by grounding the aldl for 45 secs with the key in the on position, unplug iac, turn off, pull out ground, start car.. adjust idle screw until its idling smoothly. It might stall initially.. just increase the idle and adjust it until its the lowest rpm that idles smoothly

 

and if you arent doing your own chips yet your idle will never be right

 

I just adjusted my TPS and IAC last night and it worked good until the dar thing warmed up. Then it would stall when I put it into gear. AND then the idle was **** and when I put it in Park the idle went to 950-1000 when I had just set idle at 750 and in the chip it was set at 650 so I should be imbetween those values yes no? I can't figure it out. Also my alternator is giving me major problems. I don't know what I can be. It's really pissing me off. Anybody have any sugestions?

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, Jon (350 TBI!)
91 Red My website

 

Ed Wright is doing my chips and I did what Pablo instructed already. Also I know you have to do all of this after the car is at normal operating conditions. Maybe I'll try it again. I could have done something wrong.

 

Actually when you set the minimum idle the idle speed has to be a bit below the value in the prom. Your min idle should be around 600rpm.

When you are finished adjusting, put the car in drive, let the idle settle to 650rpm and look at the IAC counts. They should read 3-8 counts. If they are higher keep the engine running and raise the idle speed a little bit. Shutdown and restart, and look at IAC again.

The reason min idle is lower than commanded idle is the IAC can only add air to the intake. If you set min idle higher than commanded idle the ECM will loose control of the idle speed.