How to clean your IAC (Idle Air Controller) valve

I realize this is an old thread, but I'm a new 05 owner and have this problem, so I have two questions. Does the TB cleaner method work on the later style of TB. Someone else asked, but I didn't see an answer. If it does, could it take multiple cans of cleaner? Mine worked until I reattached the air intake assembly.
BTW this started after I filled up with gas, (name brand).
Thanks in advance
Paul
 
RangerPaul said:
BTW this started after I filled up with gas, (name brand).
Click to expand...

When you say that, do you mean that you stopped for gas, filled up, re-started your TJ, and it started running rough? If so, did the rough running stop when you started driving or did it continue? Finally, if it continued, but eventually cleared up, it's not likely the IAC, but rather the EVAP/Purge Solenoid. Keep reading if so. Otherwise, if the rough running only occurred at idle and never resolved itself, the IAC is a likely culprit.

You can download a Factory Service Manual from the TJ Resources section here on the forum. When you do, you'll find a description of how the thing works on pdf page 1665, along with this picture of where it can be found (it's #2) on pdf page 1666:

1714687405187.png


The EVAP/Purge Solenoid is an electronic valve that the EVAP system (coded into the logic of the PCM) uses to dump fuel vapors from the charcoal canister to the intake manifold at certain times, to burn those vapors up instead of releasing them into the air. The problem is that the solenoid can fail in the open position, and then, when the PCM runs in open loop, the engines runs rich, and that causes the rough running. It's especially evident after filling up because the refueling process stirs up a lot of vapors in the tank and vent system. It eventually clears up because either those vapors get completely burned up as you drive or the system goes into closed loop at some point and the O2 sensors pick up the rich condition and the PCM reduces the injector pulse-width to get back to a proper air/fuel ratio.

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I stooped to buy gas. Fill her up, and in about 2 miles it would no longer idle. It died every time I let off the gas. CEL came on. Stayed that way for the 200 plus mile trip home. Parked for a day, then it worked fine, (cel still on) for about 8 miles the same thing. Gave a P0508 Idle Air Control Circuit Low. Cleared it. Did TB cleaner thing and that worked for a short time, so I reconnected the air intake tude and it failed again.
 
RangerPaul said:
Gave a P0508 Idle Air Control Circuit Low.
Click to expand...

That code and those symptoms are definitely an IAC problem, and I don't think re-fueling had anything to do with it. Grab the 2005 Powertrain Diagnostic Procedures Manual from the TJ Resources forum (it's the last one in the list here) to find the troubleshooting charts for that code (it's on pages 188-189). Here's the first part, showing when it's monitored, what triggers it, and possible causes:

1714696491848.png
 
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Well, I noticed that spraying the throttle body itself with cleaner wasn't getting the TB itself any cleaner so I wondered if I was getting the same results in the IAC. I tried actually wiping the TB with a cleaner soaked rag, and saw minimal difference, so I pulled the whole assy off and removed the IAC from the TB. It took quite a bit of scrubbing to clean the TB it self and the IAC was totally gunked up. Also the IAC itself was different from any of the ones I saw described. It was only attached with one screw. After some intricate scrubbing and a LOT of TB cleaner the plunger started moving again. I made sure that anything I could reach got a good cleaning. While all this was happening I had the battery disconnected so that, hopefully, the computer would forget the previous state. I reinstalled everything and viola! She runs correctly again. I drove it around for a few hours and she didn't stall, throw any codes, or turn on the CEL. Thank you sab for the guidance. It really helped!
 
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