Help with ‘04 5.4l 3v Ford Triton misfire

[Howard Shadix]

Aside from all the brand jokes. Wonedering if any of the gearheads around here might be able to help.
Got a intermittent misfire cylinder 6. Complete timing set and roller followers 4mo ago. So far I’ve replaced plug, coil, fuel injector. Compression in cylinder 4,5,6 all 180psig with no leak down in more than 10 minutes. Didn’t test the others. No coolant level drop. No evidence of damage to wiring harness. Coil reads 5.3 ohms on both contacts.
The misfire only occurs with acceleration from lower rpm while in OD or when absolute full throttle which I only found out when test driving.

Anyone got an idea?

Thanks

 

[Ken Ford]

Are you sure you are changing the right parts, Ford is unique with the firing order.

 

[Howard Shadix]

Yes, I have been operating using the same diagram you posted. Tomorrow I’m going to swap coils again to see if the maybe the new foes coil just happens to be bad too. The only code I get is the cylinder 6 misfire not the ones for coil or injector???? Mystery

 

[Boot71]

My 05 5.4 had a misfire code for cyl 8 that I fought for some time.
Wasn't until I changed all 8 plugs for a tune up that I found #1 plug burned up.
It's possible you are chasing the wrong one because the code provided is wrong.
Have you done a full tune up recently?

 

[Howard Shadix]

About 1.5 yr ago changed all 8 plugs, not coils. Ran fine. Had the old 5.4 timing knock and 5 Mo ago did complete timing set including all roller followers, oil pump, water pump. Couple of months later this started. At $60 a coil and $18 per plug it’s pretty expensive to replace them all.
I’m going to swap coils tomorrow and see if the misfire changes cylinders.

 

[Howard Shadix]

Thank you both for replying.

 

[Boot71]

Swapping coils will let you know if it's a bad pack, but if nothing changes, you may need to at least pull/inspect the plugs to be sure. I got my Ford master tech status in 2010, and STILL to this day can't figure out why I had a constant #8 misfire code, but the #1 plug was completely burned off. Neither could any of my buddies that still work at Ford. Sometimes weird stuff just happens, and you gotta get old school to physically inspect parts.

 

[Outlier]

Did you use OEM parts? Do you have a way to monitor misfire data?

Do do the simple stuff first. Swapping coils and plugs is a good place to start. If you come upon a dead end with that on the bank that the misfire is from, repeat your previous tests on bank 1.

ETA: I know this might seem oddly specific but swap components with cylinder 7 instead of 5.

Keep us updated please.

 

[Tikker]

I don't own a 3v 5.4, but this reminded me of a YouTube video I watched about this sort of issue.

5.4 3v misfire.

 

[Gingerbeard Man]

I had a misfire in our Lincoln.
For two ******* years I chased the problem. Changed coil packs, tried fuel treatments, replaced spark plugs, replaced the fuel pump. Took it to the mechanic and he couldn't narrow it down and advised against a compression test just because of how ridiculously stupid the process is to get to where you need to get to.

You know what the problem was? The ****ing battery......the battery tested out fine but for some reason it started dying quickly.
Replaced the battery and haven't had a misfire or trouble code since.

Ford has the weird 12v connections in the car that are hot 24/7. If you leave any chargers connected you have a slow draw that will slowly destroy your battery. I have a feeling that's what did it in.