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Aug 6, 2009 | 07:53 PM

kingeightclub

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Joined: Jul 2009

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help.help.help

hello all. found this site a coupl weeks ago,awsome.i have a 2003 f 250 w/the 5.4 Withe the engine on and in park runs smooth.Put in drive with foot on brake the engine misses.Also when cruising at about any speed,but not when acclerating.New plugs,fuel filter,air filter,pcv valve and clean MAF.I also unpluged each COP wile running. The engine flutterd after each unpluging witch tells me the COP's are good( i think).There is no codes and no check engine light.Been to one shop,they couldn't figure it out but said i was running 10% lean.any help would be great.thank you

Aug 6, 2009 | 08:49 PM

ReAX

Post Fiend

Joined: May 2006

Posts: 10,007

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From: Central Florida

Were the plug boots clean, black and crack free when you had the plugs replaced?
Have you checked the fuel pressure?

Aug 7, 2009 | 10:29 AM

kingeightclub

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yes , the boots were also changed w/the plugs.have not checked the fuel pressure.will try today.thank you

Aug 12, 2009 | 11:25 AM

kingeightclub

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Joined: Jul 2009

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checked the fuel presure.key on engine off 40psi.let sit five minutes 39psi.so i belive the fuel pressure is good. what to do next.i dont know

Aug 12, 2009 | 01:49 PM

Monster-4

Logistics Pro

Joined: Aug 2007

Posts: 3,974

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From: Millersburg, OH

The missing sound like a bad COP. A misfiring COP will NOT trigger a CEL in these trucks. You need to read the Pending Codes from the PCM and it will tell you the cylinder(s) misfiring.

The lean issue sounds like a vacuum leak. The line that comes off the TB and goes to the PCV tends to crack at the elbow near the TB. If it gets bad enough you should evetually get a code. Check it out just to be safe.