I have started experiencing the weirdest issue i have ever seen and I have no idea what it is.

If I rev the engine, even blip the throttle past 1200 rpm just slightly, on the way back down the rpm's would hang at 1200 for 3 seconds and then drop to normal idle.

If I am in gear, slowing down, force the rpm's down below 1200 rpm and get off the clutch, they will bounce back up to 1200 for 3 seconds and then come down to normal idle.

At first I thought it was my throttle cable getting caught, but thats not it. I thought maybe the IAC but it responds properly to the AC turning on and the fans.


I am completely baffled. It started happening just out of the blue.

 

You could try adjusting your dashpot. It will have a similar effect if adjusted out too much. Although it wouldn't really explain why your idle would just back up to 1200rpm. Something to check out, mine had a similar issue (Link) until I backed off the dashpot.

 

I should have probably mentioned that I dont use MS for idle.

 

I have the same thing and I like it. I find that it helps me in stop and go traffic. it helps with the engine not to bog down. I thought I had a stuck cable too but it seems to be normal behavior.

 

does it happen if the idle valve is disconnected?

 

I haven tried this because for me to disconnect the idle valve is a mission and a half. But I assume because the RPM's hang and then drop, its the IAC doing it.

Unless you want to tell me that if I disconnect it and the symptom stops then my IAC is acting up.


I will agree that this is an inadvertent benefit which is why it doesnt bother me that much. Still strange though.