Hi everyone, I have a 2009 f250 with the 5.4 triton. Truck has 304k on the clock. Got a number 4 misfire, random misfire code popping. Been thru all the spark plugs probably 4 times. Swapped coils all around still number 4 specific. Getting fuel. The truck drives well from 0 to about 55 but once up to about 60 or in over drive you can feel the power drop out and the truck has a hesitation when you give it more gas. I am considering doing a compression test and or pulling the valve cover off the right bank to see whats going on in there.

What do you guys think or what should I be looking for specifically?

 

I think your plan is sound. But before I did that I would swap fuel injectors with an adjacent cylinder and rescan.

 

When was the last time the fuel filter was replaced?

 

Check your fuel trims at idle, at 2000rpm and under load.. record in graph format and post results.

 

If you can , post all the data stream info, if fuel trim is off , the data stream might just show why.

 

Ok. It's been 24 hours. Up date time. I had a number 6 misfire as well. Went ahead and swapped number 6 and 5 injector and swapped number 4 and 1 injector. Only misfire is still number 4.

Truck is smoothish at idle in park or neutral, once in reverce or drive i get the lag, dropping of RPM, sluggish accelerarion. Again up to speed around 45 plus in overdrive i feel the power drop out.

When the truck cranks it sound good for about 4 or 5 cranks then it will sound weak, then jump back up and sound the same as before. I am starting to think there is a valve not sealing all the way.

 

I would put a scope on both the ignition (primary/secondary) and the injector circuits, see which is causing the issues.