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Ya, I mentioned on the JU ZJ board that I had alos dropped it in Reverse and it stalled. and to just that, someone suggested cleaning the IAC. Seemed harmless to do and easy, so I did it before going home last night.
Good news I did get from the ZJ board is a link to a place that sells just the pump and not the whole assembly. pump alone, ~ $90, vs. whole pump assemebly at $200. I'll post the link in my other thread for future reference.
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Actually, a Jeep doesn't have an IAC. In a Jeep, the part that does the same thing is called the Idle Speed Control Motor
. The ISCM is nothing more than a stepper motor that controls a pintle. The pintle then opens and closes a hole in the throttle body. The hole is past the throttle plate. The ISCM takes it's orders from the ECM. The ECM senses a need for more/less air to maintain the 14.7:1 Air Fuel ratio, and opens/closes the ISCM pintle to trim the ratio.
Symptoms of failure usually is a racing/bouncing idle. The little ISCM is really very robust, and rarely fails. Simply removing it from the throttle body and cleaning it is normally a cure. Replacement is nice, but it costs money that usually you don't need to throw at the Jeep.
When I clean it, I pull it off and spray it with Wal*Mart Tech Carb Spray. This softens the carbon and washes away about 75% of the gunk. This little treatment is followed up with a good scrubbing of the pintle with scotchbrite. The scotchbrite burnishes the pintle and cleans it up slicker'n snot.
The same treatment is done for the whole throttle body at this time. It's not hard to do... so why not. The little hole that the pintle mates with/and plugs is often overlooked. It's subject to the same carbon build up. If you don't clean that hole then the pintle sometimes does not effect a good seal. Then the idle problems reoccur.
Does the ISCM effect the running of the Jeep in reverse? Nope... otherwise it'd do it also in froward gear. The problem described would have to be somewhere else... such as fuel delivery or perhaps a problem with engine load monitoring (MAP/MAF issues).