Topic: High Idle

[underwhelmd]

94 YJ, 2.5 litre, 5 speed

Idles at ~800 when cold, then gradually increases to 1500-1600rpm as it warms up and driven.
I've replaced the TPS, cleaned the Idle Air Control a few times, cleaned the Throttlebody itself, replaced the Throttlebody gasket, removed ALL but the 4 vacuum lines needed to make it run. I checked the remaining lines and connections for leaks.  I removed those other lines just temporarily to make sure it wasn't them causing vacuum leak.

I am about to buy a new IAC (dealer only) but before I spend that $100 (canada, eh) I'd like to go over a few things.  If the intake is leaking at the head, would this gradual high idle happen or would it idle fast immediately?   How big of a job is it going to be to check/tighten the intake bolts on the bottom with the engine in the jeep? Is there another sensor that would cause high idle?  For example, my speedo doesn't work so it's throwing a "distance sensor" code right now.  CPS? 

When I took the IAC off the throttlebody, there is an O-ring there on the plunger thing but no gasket...  is that correct?

I should say that it runs fine except for the idle.  Makes good power. Thanks for any replies.

[Tall Boy]

lets see, If i remember correctly to check for intake manifold leaks we spray carburettor cleaner on the intake and if it dies there is a leak, and if not it's not leaking. At least I think it is carberettor cleaner.

[aw12345]

Brake cleaner, or simply water works also.

Art

[underwhelmd]

Thanks for the replies.  I was all over the intake manifold with carb cleaner previously and no change in idle.  I ended up ordering the IAC this week and will see what happens when it's installed.

[underwhelmd]

new IAC installed.  no more high idle.