Idle Speed

[peter paul fenske]

At 01:21 PM 12/26/96 -0600, you wrote:
>I have a friend running a 1988 Chevy 4.3l TBI engine with a Howell harness.
>Is there a sensor or some harness signal that he can intercept and
>modify to allow him to manually adjust the idle speed slightly up or down
>from the ECM setting?
>
>Thanks.
>
> - jack
Hi Jack

Unfortunately the idle speed is hardcoded vs temp lookup in the ecm.
The ecm controls a stepper motor. This is in closed loop.

However you can generally raise the idle speed by 150 rpm over the set
point with no ill effects using the minimum idle set screw on the
throttle body. Most ecms do not report a IAC error and those that do
need a difference of more than 150 rpm from the set point.

Merry Christmas: peter