My idle speed control motor on my 89 360 stays open longer than it should i think, when i let off the throttle it maintains at that rpm for a couple seconds before it starts idling down. This is the only 1st gen I've ever driven, but i don't think that is normal. I tried cleaning it up but to no avail. Is it possible to jus unplug it without stalling? Or is there a way to adjust it so it doesn't have this delay? Thanks!

 

The delay time is chosen by the computer and is not adjustable. As it gets colder the time can be longer. Mine stays up longer than I think is needed also but I believe the computers were programed to avoid the possibility of the idle dropping to soon and the engine stalling. Every thing about our trucks is very conservative to err on the side of longevity and reliability. JMHO

 

Okay I guess I didn't know if this was a normal thing or not, just kind of a pain when hookin up trailers and such, or when ya go to slow down and you don't lol. If thats the way it's supposed to be I spose I'll deal with it. Thanks SEAL
Edit: You said it varies on temp? Could a fualty engine coolant temp sensor(or a different sensor) affect this? Jus a thought since it doesn't seem to decrease at operating temp

 

I understood you to say it is doing this only at startup. My response was predicated on that understanding. Once it warms up it should not do this unless the A/C is on. What RPM is it holding it at? Have you checked the computer for trouble codes?

 

I haven't got any codes for anything, it's done this since I bought it in '07. My truck doesn't have a tack, but if I'd guess probably around upper 1000's, possibly lower 2000's? It stays there for a full 2 seconds before it idles down

 

The RPMs don't sound out of line if it is operating normally but without actually seeing what it is doing it is tough to say if anything is wrong. I would check the codes. The computer uses signals from the TPS, coolant temp sensor, and various switches to control the idle. I doubt the last two would be the problem if it is doing it when cold or hot.

1. Cycle the ignition key ON-OFF-ON-OFF-ON within 5 seconds. To cycle the ignition key ON means to turn it only as far as it takes to get the radio to come on. It does not mean to turn the engine on.

2. Count the number of times the "check engine" lamp on the instrument panel flashes on and off. The number of flashes represents the code. There is a slight pause between the flashes representing the first and second digits of the code. Longer pauses separate individual codes. For example, flash-flash-flash [pause] flash-flash represents the code 32.

A code of "55" represents end of error codes. If this is all you get then no error codes are stored in the computer. This is the normal condition

 

Ok, I've tried the key thing before and didn't get anything, so i probably did it wrong, when i get back home this weekend I'll check for codes like you said, see if i find anything. Last year I changed the TPS thinking it had to be that, but it didn't make a difference. Appreciate the good help here