Miss 5.4 SC Harley Davidson. Please help.

normalname · #1 10-20-2009, 09:48 PM

I am throwing my self at your mercy for guadance. I am lost, and don't know where else to go.

My 2003 Harley Davidson edition pick up is missing like crazy. I notice it mostly in city driving, low rpm, low speed. 20-45...I initially thought it must be a bad cop, after talking to a few guys I decided to wait a few weeks and see if it produced a code. No such luck.

Fast forward to today. Brought it to the dealership and had it placed on the power balance scope. Picture four mechanics staring at my engine scratching their heads and you will know my pain. They said "it appears to be missing intermittently on all 8 cylinders.

Mode 6 showed no miss code or pending code.
Power Balance showed all cylinders had peaks below center.

WTF, all 8 cylinders? Would the truck even drive if all 8 were missing? I cannot imagine all 8 cops are going bad. Neither can the mechanics. At this point they wanted to blindly tear things apart looking for a problem. I don't wish to devote the time or money to such a retarded endeaver. Surely someone can point us in the right direction so we can dissasemble with a purpose.

What module, sensor, computer, left handed widgit, ECT, could effect all 8 cylinders intermittently?

Thanks in advance for taking the time to offer a stranger assistance.

Mod list incase it helps.

51,475 miles
Headers with no cats, magna flow mufflers.
FTVB
E-fans
Dyno tune

Changed the spark plugs without change. Went with factory recomended plugs and gap.
Replaced fuel filter, problem persists.

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dgwoodworks · #2 10-20-2009, 10:00 PM

before anything major, I would disconect the battery and reset the computter

Matts ford · #3 10-20-2009, 10:11 PM

how many miles? was there ever any coolant leak? was there any water down the spark plug bores? check the fuel pressure. someone else may know what the specs are for that engine.

normalname · #4 10-20-2009, 10:18 PM

Quote:

Originally Posted by Matts ford

how many miles? was there ever any coolant leak? was there any water down the spark plug bores? check the fuel pressure. someone else may know what the specs are for that engine.

Cant believe I left out mileage... will edit and add.

51,475 miles. No coolent leak, or none that I saw. All the spark plugs appeared dry and the boots to be in good condition.

I have not checked fuel pressure, however the filter has been replaced.