Got a ‘17 F350 welding rig, bought it brand new got the extended warranty. Around 65k miles I went to fire the truck up around noon at work and it just spun over. Company mechanic came out to where we were working said I had moisture in the coil packs. Check engine light ends up coming on later that evening on my way home.
I take it to a small shop I trust, they think it’s a broke valve spring. Since I have warranty I take it to the dealer. They say it’s not a broke valve spring, code says misfire cylinder 5, but the truck isn’t missing. They have it 2 weeks, finally I just come get it ‘cause I needed to go back to work.
Fast forward about 6 months and 20k miles, truck started getting worse and worse to the point where it started dying in the cold mornings before work. I would auto start, let run for 10 minutes while I got ready, come outside and the truck is literally jumping(shaking) and missing so bad it sounds like it has a lope tune. The lights are dimming it is struggling to stay on. I have multiple videos of all this. It takes about 5 minutes of actually driving it to level out. Sometimes it would start fine then check engine light would start flashing while driving and it would run like total crap. After about 3 days the check engine light would go away by itself.
As of today, dealer has had it a month and says they can’t fix the truck because it won’t mess up long enough for them to hook up their scanners or whatever. Says check engine light is on, but the truck runs fine.
I literally waited months to the point where the truck was doing it multiple times a week, multiple times a day. Lots of coworkers got to see my truck messing up. If I killed the truck at work and didn’t run it for a few hours, it would struggle to start and then be missing at idle. So it SEEMS to happen more often when the truck is cold. However, it does it while driving too so I’m not sure. I don’t know if the dealer is stalling or what’s going on. I asked service manager to call Ford and I sent him my videos of the vehicle, it’s been a full week since that conversation. Do I try another dealer? Anyone had these issues, what are my options?

Oh also only in early morning the advanced trac and hillside control would go out, cruise wouldn’t work. I pull over and turn the truck off/on it would be fine and not do it again until another random morning. Not sure if that’s at all related.

 

battery good? How old is the battery? Might be some of the issue… these newer vehicles run off exact voltages down to the .01v…had weird issues with a bad battery once.

also check your ground connections on everything.

 

broken valve spring! had one do this for a year cyl#2 misfire would start up run rough clear up and be good no codes for months. they replaced coil wires plugs and fuel injector still no fix. finally #7 spring broke and i fixed it, then another valve spring broke and dropped in the cylinder. this time put a hole in the block. as the heads were pulled off could see #2 cylinder and piston was way blacker then the others. looked it over and sure as **** the spring was broke but wedged itself were it was still working somewhat. would get a #2 cylinder misfire code once a month or so for a year. spent alot of money at ford and they replaced a ton of stuff. wish i would have checked the spring first!!

 

I have to say, that another dealership
would be my next move.

 

I had the same issue with a misfire and check engine light. It ended up being moisture on the spark plugs and coils . They changed all my plugs be and two coil. That resolved the issue.

 

So was wondering on the misfire issues would it not be a good idea to 1. remove coil packs to check for corrosion and moisture and remove plug and check compression of cylinders?? it would seem to be is the issues like was stated above the misfires was at startup and when warm was not a issues adn then when the #7 spring went out it created a damaged engine issues and then the #2 spring was found.. The compression will be lower in the bad spring cylinder at least giving a hint of the issue..

the coil pack and plugs under them do not appear to be that hard to remove to check.. is that not a good plan??

 

There are resistor pills under the plug boot springs in the coils that corrode and can cause misfires. A good set of spark plug wires/boot kit will come with the resistors.

 

I’ve been a ford tech for quite a few years now. One I suggest going somewhere else, two it sounds like you have a bad valve spring or something wrong in the upper valve train. I would suggest taking the coil currently in the problem cylinder and moving it over to a different cylinder. See if the code follows. If it does then replace it. If it doesn’t gonna have to dig deeper. The coils on the 6.2 are notorious for arcing to the cylinder heads so don’t jump the gun into the valve train until you verify. Next time it’s doing it open the hood and watch that coil, you’ll be able to physically see it arcing if it’s bad enough, if not get yourself a spray bottle and soak it down.

 

Ford Boss has a video that shows what the arcing looks like at night.

Sorry, having issues posting link but it's on YouTube.