problems with GM TBI

[Bruce Plecan]

Subject: Re: problems with GM TBI
Diagnosing IAC,  short the A-B (top right hand two) pins of the ALDL
together,
and turn the key on, don't start motor.  Listen to the IAC motor.  Uses a 1
1/16"
wrench to tighten into the side of the Throttle Body.  Has 4 wires coming
out of it.
You should hear a wrirrring sound,  if quite,  hook up a little no 67 (dash
bulb)
across the two green, and two blue wires for a moment, and it should
flicker.
They control a stepper motor, IAC.  If  you hear the whirring then ya know
the
wiring is fine, and then motor runs, about the only thing left is the Port
when the
pintle runs being carboned up.  Use a wrench remove the IAC, and using Carb
Cleaner remove as much Carbon as possible.  Reassemble.  Test drive til warm
and over 40 mph to reset IAC motor.


>Sounds like an Idle Air Control "IAC" solinoid/motor might have gone bad.
>Jeff Bratcher wrote:
>> Upon cold start up it would run great until I shut it off. When I
>> immediately restart it (ie after going into a store, etc.) I noticed
>> that it would stay at high idle and would not come back down to normal
>> idle until the Jeep was shut off and sat long enough for the motor to
>> completely cool off (overnight usually).
>> <snip>


Does the thermostat work?.

Cheers
Bruce
If it gets wierder then the above e-mail me off list, and I'll try to walk
ya
thru it