'89 Isuzu Trooper with cold idle problems. Stalls until warm-then, idles fine. Checked the under-console diagnostic leads and get message regarding "cold idle solenoid". Cannot find this. Is it more than just a piece of pipe? That's all I can find on microfiche at Auto Zone.

Check coolant temp sensor. These fail often and cause all kinds of mystery problems. This unit acts much like a choke on old carb engines and can fail in different ways. Most common (I think) they fail such that the ECU thinks the engine is cold when it has begun to warm and thus the ECU delivers too long a pulse to the injectors so that the engine runs way too rich. I think it is also possible for the sensor to fail at any point between cold and warm such that the fuel mix is wrong except for the particular temp at which the sensor is stuck. Also O2 sensor has some fuel "trim" input.

Check glow plugs and valve clearances, both of these will cause bad cold starting, but once hot will start fine

Sounds like an Idle Air Control (IAC) motor to me.

hi,
plug the EGR line and see how it acts. better yet put a ball bearing in that line and reconnect it to the EGR and see if it goes away. definate vacuum issue somewhere. tranny modulator, check every line coming off the firewall manifold. the throttle position sensor might need to be replaced. its one of the only moving sensors under there. on my 89 tempo I could adjust my idle, move that idle screw around so it idles up a bit to get it out of that dead area on the TPS. plug wires after that. those notchbacks are getting extremely rare, and with a V8! put it far far away....

jm

On modern day cars the parts that get fitted need to be adapted to the ECM using a decent diagnostic machine. I bet that this was not done and the car is now suffering as a result.
Something to try is resetting the ECU, simply disconnect battery for 10 minutes, reconnect, then start car from cold *without touching gas pedal* and leave idling until the rad fan comes on (this resets all the base idle settings) then take it for a drive - hopefully will solve the problem

check for spark at the coils under load. May have to change some ignition coils.

I had the same issue on my 99 Trooper.

It would usually start when completely cold, but idle around 2k RPM.
It would drive fine. But if I shut it down, ran into a store, and came back out, it would start but immediately idle.
Had to ride the gas a little to get it into gear.
The Check Engine light has been going on and off for 6 months or so.

I took this to my local trusted repair shop (no Isuzu dealers within 200 miles).
The diagnosed the light, and found that the Intake Gaskets were bad or leaking.
The idling problem was related to the car not being able to control the amount of air coming in.

They replaced the Intake gaskets by the next day, and I haven't had a problem since. And no more check engine light, which has been on half a year.

Here's some details from my bill:
(1) Intake Gasket set $107.95
Misc materials $21.00
2.1 hours of Labor

The total cost to me was $345.00, and I definately don't feel gipped.

If I remember correctly it is the EGR valve. That simple. it is the round thingamajigger with vacume tubes comming aout the top and bottom side, its in the back (firewall) to the right of intake manifold on 4 bangers. Also check all vacume hoses for cracks, connectors etc. Especially right under the intake manifold where ther are three of four together, they get bunped off easially. also when you turn on the Defrost it will help to increase idle untill warm. don't forget to check air filter too. if dirty it can cause the vacume ssensor to missread and please make sure it is all sealed properly, clamps tight.

many automobiles behave that way on a cold start, so you don't have to worry about it. just continue to rev the engine until it is warm!

my trooper will not idle properly /it takes to long to warm up/after it warms up it rides with a high and low idle