1998 Ford Expedition Turns off in reverse

1998 FORD EXPEDITION
210,000 MILES • 5.4L • V8 • 4WD • AUTOMATIC
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RICHDREW87
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My expedition turns on fine and in drive it also runs fine but when put in reverse it either starts to turn off and I'ill give it a little gas and it stays on or it will turn off completely. Took it to a mechanic because additionally to turning off in reverse it started to turn off when I was at complete stop, mechanic said he changed auto control valve and when at a stop it no longer turns off but still does when put in reverse.
Dec 17, 2013 at 9:01 PM
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WRENCHTECH
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You may have a bad IAC ( idle air control) but try eliminating any vacuum leaks and cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle.
Dec 18, 2013 at 2:27 AM
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RICHDREW87
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Already changed out the IAC but it still turns off when i put it in reverse, what else could it be?
Jan 13, 2014 at 6:49 AM
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WRENCHTECH
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Did you scrub the throttle body?
Jan 13, 2014 at 7:02 AM
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RICHDREW87
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yes scrubbed throttle body and no leaks either and still turns off in reverse.
Jan 15, 2014 at 2:04 PM
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WRENCHTECH
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It may have something to do with the engine shifting an moving wiring around. You may have some wires somewhere that are chafed through and make contact with something when the engine shifts.
Jan 15, 2014 at 2:41 PM