Hello everyone. On my 2004 5.4 screw, 197k, I am getting a studder and a cel when I tow my boat. 1 year ago I changed the plugs and since 4 broke off I ended up doing a head job. I replaced all of the stock components with the kit from Amazon that was recommended here (new chains, guides, followers, vcts, etc), It was all Ford products and the truck ran great for almost a year.

Then, one day when it was raining I had the dreaded studder and my cel came on. The codes were The generic P0325 and the other code indicated cylinder #8 misfire at that time. I changed the coil pack and boot in cylinder 8 and put her back together. It seemed to be fixed BUT...

When it rains, or when I tow my boat the truck starts to studder as soon as it goes into overdrive.

I bought my truck new and have been here since ‘04 so I know the normal fixes and have tried them. I even changed my oil to make sure my vcts were working correctly.

I do need to change my fuel filter, and this issue only started after I put a can of sea foam in the tank, but that could be a coincidence??

Im pretty stuck here, what would you guys recommend? The truck won’t do this when driving normally, only when raining or pulling the boat BUT I can feel that it’s not running 100% smooth at idle. I can feel a misfire even though the light goes off after 2 days of driving.
Thanks for any advice, Chris.

 

I would put two bottles of Chevron Techron or Gumout for high mileage engines in every tank of gas for a while and see if that helps. There could be excessive carbon buildup on the pistons causing detonation.

 

Do NOT put Seafoam in the gas with a port fuel injected engine and catalytic converters. Techron is safe.

What brand spark plugs did you use? Did you use dielectric grease in the coil boots?

As a test, try using high octane gas when you tow.

 

I’m going to change the fuel filter and run a couple bottles of Techron through it with some 93 octane as a start.

I cant remember the part number, but I used the most recent updated spark plug that was recommended on here.

The odd thing is that I can feel the misfire when it’s wet out and before the truck gets up to operating temp.

I did did use dialectic grease on the boots, both ends, and every one felt as if it made great contact.

Even though I can feel a rough idle at start up the cel does go off after a few days of normal driving but as soon as I hook up the boat the cel pops right back up.

I really wish it wasnt the #8 cylinder that showed the misfire first as it’s the hardest plug to pull! But, I haven’t had a cylinder specific code since switching the coil packs.

 

Probably help, but cleaning the throttle body might be a good thing to do. It might help smooth out the idle.