IAC numbers way too high

[JonnyBoost]

ive adjusted the IAC screw almost all the way back towards the firewall and the scanmaster #'s are still in the 70's when at idle(closed loop). the car is barely able to maintain idle w/o dying (550-600 rpm's)

WHAT GIVES!!

 

[TurboDave]

Because adjusting back like that is in essence, closing the throttle blade which in non computer cars would reduce idle rpm. However the computer sees this reduction in rpm and raises the IAC numbers to compensate and maintain the commanded rpm.
The further back out the screw goes the higher the IAC. Conversely, the further in you screw it, it will eventually bring the numbers down.
But remember each full revolution or two of that screw must also be accompanied by a re-adjustment of the idle TPS setting. They work together, and must be kept in proper adjustment.

 

[JonnyBoost]

how long does it take the computer to re-calculate.... it seems if i go the other direction with the screw the engine rpm jumps to about 900-1000

is it okay for it to idle that high...and will adjusting the tps back down after bring the idle back down to an acceptable level

thanks for the help

 

[TurboDave]

It should only take a few seconds for the rpm to come back to normal.

A good rule of thumb starting point for the air bleed screw is to set it so that you can just barely see the first thread starting to show through the FRONT of the mounting boss. Set it there and then also make sure your TPS is properly adjsuted and then and only then, start the car and check to see what the IAC numbers settle on WHEN THE CAR IS WARMED UP.

No adjustments or chages should be made in this area until the engine is at full operating temerature.

 

[JonnyBoost]

thanks dave,

ill give the 1st thread thing a try, it sounds like a good starting point