f250 triton problem

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May 22, 2006 | 08:52 PM

gvsu141

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f250 triton problem

i have a 1999 f250 superduty with the 5.4L triton with about 260k miles. sometimes at idle it will drop to about 400 rpms and starts loping. when given even just a little gas, it runs fine. it only will do this at idle. i was wondering if anybody has an idea on what this could be.

May 22, 2006 | 08:55 PM

gvsu141

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also, when hooked up to diagnostics it came back as running lean

May 22, 2006 | 09:35 PM

FortyFords

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Change the IAC (Idle air control valve),the most common problem of hunting idle.Was there codes in memory ?
could be a vacum leak also
Rich

May 22, 2006 | 10:42 PM

ReAX

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From: Central Florida

yep IAC and pull the throttle body and wipe the gunk off of it.

May 23, 2006 | 06:27 AM

kenneBF250V10

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From: Mount Airy, MD

I agree with FortyFords, try replacing the IAC valve for starters. You mentioned that a diagnostic test reported a lean condition, that definitely sounds like a vacuum leak. I had the same problem immediately after installing my supercharger. I don't remember exactly what the codes were, but it was running lean on banks 1 and 2. I tracked down the vacuum leak, fixed it, cleared the codes and the lean condition was gone. Check all of your vacuum lines for cracking and replace any that look bad.

May 23, 2006 | 08:44 AM

gvsu141

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thanks ill try that, but where is the iac valve located?

May 23, 2006 | 08:59 AM

kenneBF250V10

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From: Mount Airy, MD

Right on the back of the upper intake. It looks like a little silver canister with about a 1 1/4" rubber hose and electrical connector coming off of it.