low grade misfire

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Feb 18, 2008 | 11:07 AM

dalman

Thread Starter

New User

Joined: Oct 2007

Posts: 12

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low grade misfire

I have a 04 Screw w/ about 95000 kms (60000 miles...on the 5.4L) and I am getting a strange miss/shudder. I seems to only happen when I am going downhill at about 110km/h @ 1800 rpm ish in cruise control. (obviously in OD) At first I thought I had gone over a big frost heave, but it happened again and the last trip. It accelerated just fine and if I keep my foot lightly on the gas it appears to go away. I did read a thread in the tranny section about the low grade misfire and replacing egr valve, COPS and plugs.... what I do not know is if it is more transmission or engine related..as it does "feel" like it is coming out of the rear end. Any ideas?

Feb 18, 2008 | 12:16 PM

mattd17

Fleet Mechanic

Joined: Dec 2004

Posts: 1,365

Likes: 6

From: Ketchikan, AK.

the 5.4 will get a good shutter in OD with a bad COP. when i had my 99 superduty, i thought i had a big problem since i had never felt it before, but it just turned out to be the #4 cop.