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John Mc
John Mc, Ford Technician
Category: Ford
Satisfied Customers: 6240
Experience:  19 years Ford Lincoln Mercury experience
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My 2003 Ford Expedition (4.6l V8) has a bad idle surging problem.

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My 2003 Ford Expedition (4.6l V8) has a bad idle surging problem. After the engine is warm, the idle will surge from less than 500rpm (and occasionally stall) to around 1300rpm. The engine seems to be running fine at speed - it is strictly an idle issue. I have cleaned the MAF sensor and checked around for obvious vaccuum leaks and found none. I have read forums that point to the Idle Air Controller, but I'm not sure where that is. Suggestions?


Hello, I am John, a Ford dealer technician.

I hope I can help solve your problem quickly and accurately.


the iac valve is located on the back of the throttle body housing. it is the size of a half can of redbull. try tapping on it with a small hammer when it is acting up. if it clears up, that is your problem.


Thank you,


JustAnswer Expert

John Mc and 5 other Ford Specialists are ready to help you
Customer: replied 8 years ago.

Not sure about the IAC. Didn't see anything that looked like Red Bull. :-)


However, in my banging around on thingsI think I did finally find the problem - a large vac leak in the elbow of the large line running from way in back of the throttle body to the passenger side valve cover. Is that the EGR valve or the PCV valve or neither?


Soon as I put my finger over the gaping hole, it idles right down nice and smooth. Looks like it wasn't the IAC, but I do appreciate the help. I'm sure I'll be in touch again.