recently, sometimes at startup after a cool down (overnight, or after a work shift), my '92 will have a low idle - to the point of stalling. But it is intermittant. I cannot tie it to low temperatures or the like, so far. Is this sensor related, or fuel line ? I use Sunoco Super (94 Octane) so the gas is good by-and-large.
Any ideas or similar experiences ?

 

Might be the IAC (Idle Air Control) valve. Do an IAC reset. You can find the short procedure in the C4 tech tips section of the forum. If that fixes it for awhile and then it starts doing it again, IAC probably flaking out on you. Otherwise I would check fuel pressure. Could also be EGR valve sticking open just enough to screw up idle.

 

Thanks for the tip, I'll go do a search now !

 

From the tech tip:

"Reset IAC valve pintle position:

A. Depress accelerator pedal slightly.
B. Start engine and release accelerator pedal, run engine for 5 seconds.
C. Turn ignition “OFF” for 10 seconds.
D. Restart engine and check for proper idle operation. "

 

Thanks - I do not have a shop manual :(
so finding the IAC may prove to be a challenge for me, but from the Tip, all I should have to do is disconnect the elecrtical feed, then reconnect ?
I'll go check my Corvette Fuel Injection book by Probst
thanks again

 

What is your voltage like at startup, and if voltage is low how old is the battery.

 

You needn't pull the electric power from the IAC to do the reset. Just do the part of the procedure I posted above. The IAC is on the passenger side of the throttle body, on the lower part. It is a cylindrical shaped solenoid with a long flat oval terminal pigtail for electric power plugged into it. It sits horizontal as it goes into the throttle body. But you don't have to mess with it unless you intend to remove it and clean it. which is not difficult but the solenoid portion of the sensor is delicate and care must be taken when cleaning the valve pintle not to compress it down any or pull it out any whilst cleaning it. Do not spray any cleaner down into the solenoid area when you have it off (if you clean it). It can seep into the solenoid and screw it up. If the air channel in the throttle body for the idle air source (the air channel the IAC pintle controls by the solenoid moving the pintle in and out) is dirty the throttle body should be removed to clean the idle air channel. If you still have coolant flowing through the throttle body you will not be able to remove it completely from under the hood and go set it on a bench or anything but should be able to get it off enough to clean it and the idle air channel. Don't remove the plastic top peice of the throttle body (referred to as ID plate even though it is blank)-- it's gasket is very prone to damage upon re-install if you overtighten the torx bolts beyond just snug).

 

I'll have to check - voltage is usually above 14.1 on the digital display and higher on the analog

 

Great - I can do that - I have to go pick my son up in an hour, so I'll try it then. Many thanks for the description and location of the IAC :cheers: :cheers:

 

The guilty part ---- cracked distributor. WHo'da thunk it ! It's got it's MOJO back ! :chevy