Hey Y'all,
My 3.1 MPI is being cantankerous again.
I went through the proceedure to set minimum air as follows:

Jumper the ALDL, turn ignition "on" without starting the engine, wait 30sec, unplug the IAC, unhook the jumper, and start the engine. I set the minimum air to allow 650 RPM in drive with the brake on when at operating temp. I reconnected the IAC.
All worked well for a week, until I took a road trip to some cooler climates. Soon it is back to it's old crap, start it up cold, and it first goes to 1700, then up as high as 2500! The throttle is not sticking, and when warm it will idle at about 14-1500.
I have repeated the jumpering, turn key on, wait 30sec, unplug the IAC rigamorole two or three times and it tames it until I drive a bit, then it's back.
I don't think the IAC is at fault, due to it obviously extending all the way when you do the adjustment process.
Let me add, the "Check Engine" light DOES NOT work and I am not ripping the dash apart to get at the bulb, so I can't check fault codes.
What might cause this? What sensor(s) give the IAC the signal voltage to raise the low idle speed?
Let me add that the timing is at 11 degrees, plugs are new, fule pressure is good, and I find no OBVIOUS vaccum leaks.
Also, I have a hesitation right off idle.

Ideas anyone?

Eric

 

You might want to reconsider this. It really isn't hard. I changed a bulb in my instrument panel in 15 minutes. Also, the bulb could still be good.....it's possible that you have a bad ECM....although unlikely.

You could have codes set that can help you fix the car....but if you don't fix the light or get access to a scan tool you're just making it harder for yourself.

 

My Haynes manual shows having to remove the dashboard to remove the instrument cluster in my '91.
Is it that easy? How do you get the **** off the light switch to remove the bezel around the lights?
E

 

you say the "Check Engine" light DOES NOT work also

seems like ECM trouble

 

You mean these lights are not prone to burning out, and the part of the ECM that controls this function could be not sending data to the lamp? The light should come on when the ignition is turned on, correct? And go out once the engine is started, providing there are on codes set.
It also occours to me that I had the battery disconnected some time while I unhooked the IAC and set minimum air, then it was fine for 500 miles or so. I'll bet something set a code, caused the problem and my disconnection of the battery cleared the code from the ECM and it ran fine until the condition popped up agian, causing the ECM to send the signal to raise the idle. The IAC is working fine, just doing what the ECM is telling it to based on some fault elsewhere.

 

you have to get a normal checking code, I think its 32 - when you turn the key. Do the check with the paperclip and see if there are any flashing codes coming up - if no flashes :hail:

 

You don't have to remove the dash. I have the same interior as you.

To remove the light ****, you have to pop out the little panel below it, then reach in with a screwdriver and press a button to release the ****. It's a little tricky. Also, when the **** is out your lights will be on so put it back in after you take the bezel out.

All you have to remove is the panel underneath the dash, the light ****, the bezel, and then pull the instrument panel out. You'll have to tilt your steering wheel down for it to clear.

Also, if the light IS NOT burnt out....I'd look towards replacing the ECM.