High Idle

[johnm]

My 99 is doing something that's a little weird, and I'm wondering if you guys have had similar experience so maybe can help me out.

 

With the AC on, the idle in Park is 900, then after I speed up and slow down, it gets a little higher every time, like there something sticking.

 

With the AC off, it's around 700-800 and seems to drive and act normally.

 

I know the idle is supposed to go up slightly with the AC on, but not that much right? It did this for a while when I first got it, and then stopped doing it for a couple months, then it did it for a week and then stopped and now doing it again. Anyway, I'm wondering if the cable actuator over on the right side of the engine bay is sticking or getting a bad signal or something?

 

Any thoughts would be appreciated.

[johnm]

Follow up/more information.

 

The pathy is doing this following a throttlebody/intake cleaning treatment. I realized the other times it has done this is after replacement of parts (the first time the distributor, the 2nd the spark plugs). It's not generating any SES codes. After doing some reading of the service manuals and the interwebs, the only thing I can reasonably guess is that the ECU "learned" settings are causing the high idle. Since there doesn't seem to be an easy way to reset the ECU to the factory default (other than with a diagnostics comp), I guess I'll have to live with it until the computer relearns.

[skulptr]

is your a/c clutch engaging?? if its not engaging the idle can stay up like that

[johnm]

yes, the ac clutch is working.

[tekazgtr1984]

Mine did the exact same thing after cleaning the TB. It was annoying as hell as I could never figure out what it was...

 

It just went away one day and has been okay ever since. I'm guessing the same should happen for you.

[Alkorahil]

Next time you start the truck, as soon as the engine turns over and starts, as you replease the key stomp the gas pedal quickly once to the floor.

This will clear out the IACV which may be sticking.