hi all,

I just found this and I want to share...

*the problem: *
high idle and it can't be adjusted lower...

*things done:*
- clean and check throttle body
- replace and adjust the TPS (throttle body switch)
- replace the temp2 sensor
- replace oxygen sensor
- replace all vacuum lines
- new air filter
- clean AFM
- new throttle body gasket
- clean and check throttle body valve
- replace the ICU, idle control unit with a known good one from a perfect
running van

and.. the idle still hanging high about 1500 rpm *(with the idle screw
closed all the way down)*

I was temped to replace the Idle Air Control Valve...but since a new Idle
Air Control Valve is pricey ($240.00) I tried this last attempt before
throwing it away although it seems working good (it vibrates w. ignition on)

*the discovery and fix:*
in the back of the Idle Air Control Valve, between the 2 connectors,
there's a small allen screw....
- I turn the allen screw out (counter clockwise), put it back on and the
idle went even higher (1800 rpm)
- so I turn the allen screw in (clockwise), put it back on and the idle
went lower (1100 rpm)
- after giving that allen in one more turn, the idle went to 900 rpm
- I left it at 900 rpm and open up the idle control screw to set the idle
at 950 rpm..

now I have a perfect idle at 950 rpm w. the idle screw in the middle..
which I can play with it..

I think for some reason the idle control valve is pumping a higher volume
of air and the allen screw is lowering the air volume either by lowering
the speed of the pump or restricting the air.. *(my theory)*

if you have similar problem try it

dan