Idle Fluctuates

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Jun 22, 2016 | 02:50 PM

coreymp1992

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Joined: May 2016

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Idle Fluctuates

I have a 2002 F250 Super Duty V10. when idling while cold the rpms will fluctuate back and forth a hundred rpm or so till it warms up a little. any ideas?

2002 Ford F250 XLT V10 (6.8L) 6 Speed Manual 4X4

Jun 22, 2016 | 04:51 PM

kcducttaper

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My first thought would be the EGR valve. A lot of times, the EGR opens up a bit more and the engine will run a little richer when it's cold just to warm the motor up quickly. Once it warms up, the engine leans out a bit and the EGR reduces flow a bit. That would be my first suspect at least.

Jun 22, 2016 | 05:49 PM

stufarmer

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Joined: Jun 2014

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From: Tampa

You didn't mention you had a Ck Engine/Service Engine Soon light on.
I'm going to suggest you clean the Throttle Body. The Symptoms you've described are typical of a Dirty/Sticky Throttle Body.
Periodically the Throttle Plate becomes dirty, it then begins to Gum up around the Throttle Plate restricting air intake resulting in an Idle Fluctuation. The cooler the engine, the stickier the Throttle Plate is.
This procedure is very easy to do. Only if this doesn't correct the idle fluctuation would I suggest looking any further. The only thing you'll be out is a can of Throttle Body cleaner.