My 02 Expy is running rough, most pronounced at idle, but also at take off and moderate driving RPM. Throwing no codes. Fuel filter was replaced last year, air filter is still serviceable, cleaned MAF and throttle body. After doing some reading I pulled the IAC and cleaned it out. I noticed before I slapped it back in last night that the valve spring was still not completely freely moving. I could reach in with my finger and actuate it down, but it does not want to freely return to its normal (closed?) position. Returns about half way then seems to just stick, it will close but it doesnt seem to want to.

Doesnt seem to have any trouble starting, running or driving, it's just really rough, and has a sputtery sound coming from exhaust. Thoughts?

 

Sounds like a dirty IAC. Could also be a vacuum leak in the IAC tube/connections. Use the search button above and in the Advanced Search, enter Cleaning IAC and see if you don't get a lot of hits explaining what is involved.

 

Cleaning IAC search is what prompted me to remove the IAC and clean it in the first place. Started by spraying liberally with throttle body cleaner, had read that its good to fill it with cleaner and let it soak and break down some of the hardened carbon, but the cavity does not "fill up", the cleaner just leaks out the back of the IAC. So I placed in a ziploc bag and filled that with cleaner to the point where the IAC internals were immersed for about 30 min, pulled out and cleaned, actuated valve, etc. Probably spent an hour total cleaning this thing up, and still it would not fully actuate to the closed position on its own.

I guess Im just looking for confirmation that A) my symptoms would possibly indicated IAC, and B) the IAC should indeed actuate more freely than I am seeing. Obviously do not want to go drop $50 on a part that doesnt need to be replaced.

 

Ok, got it. Have you checked for vacuum leaks at the rear of the throttle body/manifold? That elbow tends to crack.

 

I have not, and Im honestly not even totally sure how to check for vacuum leaks, aside from just listening for the sucking?

 

You have to work the mechanicals (the plunger) inside the IAC while cleaning. To clean you ONLY use a lubricating cleaning agent such as Deep Creep or WD. DON'T soak it, you'll compromise the seals. Using compressed air to assist is best as this will force clean/lube in places that otherwise can't be reached.

I doubt it's any good since you soaked it. Ford labeled this valve as "non serviceable" since the chances of someone doing this correctly isn't in the cards.