I have a 2001 F 350 with a V10 it keeps coming back as a misfire on cylinder 3 and 4 I replaced all of the coils and plugs and pigtails I have even swapped out the coil packs from side to side and I still keep coming back with the same code the truck has a bad check around 1500 RPM with a load on the motor mainly doesn't in overdrive and first starting off any help would be greatly appreciated

 

I would do the fuel injectors on those cylinders. I had misfires on my 2008 5.4 and both times it was the injector...changing the plug and coil pack first.
Possibly need to have compression checked if injector doesn't solve the misfire.

 

I forgot to add there is new fuel injectors new fuel rail and I have done a compression test and I replace the O2 sensor

 

Any signs of coolant in the spark plug wells? Reason I ask is there is a heater hose near cylinders 3, 4 & 5 and when it leaks, coolant pools up around those cylinders' spark plug tubes causing it to misfire.

 

When I changed everything it was all dry and I just checked again it is still dry

 

Try replacing 3&4 coils with 1&2 coils.
Just because it's a new part does not automatically ensure it is a good part.

edit, nevermind, I see you tried swapping coils already.

Are you the one doing the work on this vehicle?
It wouldn't be the first time a "professional" skipped that side on a plug change in a V10.

If you are certain all the parts are good, I would suspect wiring to the PCM, either the coil wires and/or injector wires.

 

Computer says it's a misfire on 3 and 4? Or you do? Misfire monitors aren't always accurate. Pull an injector plug or coil plug with engine running and see if there is any change. That's assuming you can easily replicate the problem either at idle or while holding a consistent RPM, which it seems like you cannot really do, based on your description

You may just be chasing your tail here, if the actual misfires are not where it says. Otherwise, REALLY good advice above.

How many miles? With an engine that old it could be a timing issue. Based on a Rock Auto search, you have a timing chain and not a belt. My 2.5L Jeep engine had a timing chain that was slacked. I was chasing the issue for two years with an intermittent misfire until it finally slacked so much it would stumble at idle, and I could diagnose it. It showed up as a single cylinder misfire then the misfire kept jumping to different cylinders.
2.5L Intermittent Random Misfire - Jeep Wrangler Forum

A slacked timing chain could retard the timing which could cause knock in a cylinder or cause a half-assed power stroke. This could show up on a compression test.

What are your compression numbers, and what is the spec range for your engine? Even if you are within spec, if your compression is on the bottom end of the range, that could indicate a slacked timing chain.

 

Quick question. Did you delete the previous data stored on your meter? If not, you will likely get the same results until you clear it and run a new diagnostic test. At least, that's the way my meter works. Just my 2 cents worth.

 

I have done all the work on the truck myself my schedule is the one telling me and misfires are on three and four I've cleared the data several times there's a few guys I work with who have also tried chasing down everything on this truck we are all stumped we even took the coil packs off of one of my old V10 that all work but it blew a rod through the wall and it still came back as 3 & 4 misfire it shows up 6 codes the same code three times for each cylinder

 

What exactly are the codes?

I don't understand what means:
"my schedule is the one telling me"

 

Assuming you've done a compression test, I hate to say it, but I think you are looking at a tear down to find your cause. At this point I'm thinking worn camshaft lobes which would also give you a misfire read on your diagnostics. But before you do that, remove the valve cover on that side and check the lifters and pushrods for those cylinders. Inspect the pushrods for unusual wear on the sides and measure the length to factory specs. I mean, at this point you have to think outside the box a little and get creative. Again, just my 2 cents worth.

 

Also, make sure you are really looking at cylinder 3 and 4. I have seen guys troubleshoot the wrong cylinders because they try to apply the GM numbering scheme to a Ford.

 

x2.. it does happen.

looking down on engine.. the side most forward is #1.. on a V6/V8/V10.
on the compression test.. I hope the throttle body was wide open.

I know, old stuff.
intake valve open
air in
fuel in
all valves closed.
spark
power
exhaust valve open
push exhaust out.

start over.



ALSO,, possible intake leak between # 3 and 4....

 

Where are the push rods on a v10?

 

I am not trying to be a Smart A$$....

but when the problem is not easy to find.

start with the basics... the basics will direct you to the problem.

50 years of wrenching does tell me this. it is a gas engine..
the rules of a gas engine running has not changed...