So, I just got back from a 5000 mile eastern coast loop from Maine, towing an aluminum 14' cargo trailer conversion (trailer converted into a camper). The trailer is probably 4000 lbs. My 2015 5.0 v8 3.31 differential xlt was a pleasure to drive and be in for hours. I've told people that it was like 'driving my living room'. The truck has now, 8000 miles on it.

Observations

Yes tons of things were good, pulling power, uphill, downhill, comfort, electronics conveniences. I don't have to mention this stuff. Anyone who has one knows.

Some things that I find interesting:

Towing gas mileage
I used to have a teardrop trailer. About the same weight as this V nose one that I have now. This was my first long trip with it. My teardrop was low. It's height was barely above the top of the tailgate box. My gas mileage with this truck has been averaging 21.4 mpg (checked only using the trucks readout) without the trailer. With my old truck and trailer I lost about a couple miles per gallon. On this trip I averaged 12.2 mpg. Quite a drop. I figure it's because of two things. One is that the gearing on this truck and 6 speeds is designed for better mileage with nothing in tow. Second, The very tall profile of my cargo trailer compared to my old one probablly contributed to most of the mileage drop because of air drag. The truck would often be in gear 4 or 5 when towing compared to 5-6 that it usually is without anything in tow. Right now gas is cheap so it's not a big deal. I figure the good gas mileage I usually get is worth it as my long trips are usually only once or twice a year.

5-4 downshift
I think I have the hard downshift issue in these gears. I noticed it more on the trip as I often slowed considerably on steep inclines and the automatic downshifting was a hard clunk dropping from 5 to 4, noticable in the cab. I believe there is a software fix for this and I'll be having that looked into with my first oil change.

Engine surge
The engine would rev up when downshifting from 2-1. This only happens in tow mode. It sounds like when you mistakenly put the truck in neutral and step on the gas thinking it's in gear. I get a short one second rev of the engine when it downshifts. Anyone else have this problem? I haven't read anything about it here. Possibly because tow mode isn't used a lot by people.

Speaking of hills.
I've never had a vehicle that sensed hills while towing and adjusted gears on a steep downhill grade. It's really nice and works well. You almost don't need the brakes. It automatically gears down and does it nicely, as if I had done it manually.

Foot vent won't open
One thing I hadn't noticed before, but the lower vent doesn't seem to blow any air. Even when the fan is turned on high. I'll need to further check this out and take it in to be checked with my first oil chainge

All in all the truck made this trip a pleasure. The amenities are super nice. The wife is happy, and the truck performed with a load uphill and downhill admirably.

 

My F250 has a similar surge when downshifting in tow mode. Havent towed yet in the f150 but they are serious about tow mode on the F250 6.2L compared to other trucks I have owned. Unloaded it seems like it almost will lock up the rear tires when downshifting if in tow mode, very firm shifting too.

Not that this applies here but there is probably and explanation such as the converter stays locked or something.

 

The 2-1 downshift sounds more like rev matching from your description. The jump between gears 1-2 is pretty significant so it sounds like the PCM is reving the engine a little bit to smooth out the shift.

 

My thoughts exactly.

 

Just FYI on the hard 5-4 downshift. I have experienced the same issue. I just had my truck at ford for a warranty repair on a bad cv boot and thought I would get them to fix the downshift while I was there. They told me I would have to bring in the trailer loaded with whatever I was pulling when I experienced the problem and let them duplicate it or Ford would not warranty the fix.

The issue with that for me is that I was pulling an 20 foot trailer with a 35 hp John Deere tractor and equipment. I am not about to load all that up and take it into the dealer.

I am going to check around at other dealers and see if this is requirement everywhere of if it is just the one dealership.

 

The TSB for the harsh 5-4 downshift is 15-0142. I had it done and it fixed the problem.

Telling you to that you have to bring the trailer in to get it fixed is pure bs.

 

Yeah I agree its bs. I had a copy of the TSB with me and they still told me that.

I will be checking with another dealer.

 

Thanks for posting this up. My truck while in tow/ haul or sport mode unladen even is very rough 5 to 4. A couple of times it felt like I was rear ended.