Must be a Tow / Haul mode thing and/or shift strategy, since 2nd-4th gears on the 4R100 and 3rd -5th gears on the 5R110 are identical. Regardless, towing 7K lbs with OP's pickup and gearing should'nt put much strain it.

I tend to shift my 4R100 manually through the mountains, but the shift strategy updates that these tuners offer has my interest. Certainly seems the transmission updates are appreciated even more than the nominal power gains.

 

So any thoughts on accepting this under preforming engine and swapping in a 6r80 trans with a stand alone controller.?
Won't be cheapbut would give me 2 additional gears to help out. Would like a 6r140 or 10 speed, but no controllers available.
A 2020+ 7.3 dually will go over $60k so worth some investment to fix this truck, and no sense putting another gutless 6.8 in the truck, I know of no other gasser dually I want to invest in till the godzilla showed up. I had a good 7.4 chebby, but have to go too far back to find one of them.

 

First I would verify if the “tune” on the truck is actually an old school chip vs an electronically loaded tune, like all of the modern tunes. If it’s a chip plugged into the PCM that will need to be removed before loading any new tunes from a handheld tuner.
The truck with its combination of mods should pull your 7K TT easily through PAs mountains, something is definitely out of whack. Have you changed the plugs and boots yet? Even at the low mileage you have the parts are still 20 years old and any degradation in the spark will kill power under load. Fresh fuel filter?
My ‘05 2V V-10 Excursion (the big wagons never got the 3V motors) with the 4R100 has the Banks headers and Y pipe with a free flowing muffler, 35” tires and 4.88 gears for an effective 4.39 gear ratio and 5Stars 89 octane performance tune with matching fuel is our dedicated tow rig. It pulls our 41’ TT with 3 slides and lots of mods that scales between 12 & 13K depending on water load and rear rack loads. I also tow at 65 MPH and typically see between 7.5 (lots of stop & go in small towns) and 9.5 MPG (open highway on flat-ish terrain). The towing performance is more than adequate, my tune forces a downshift out of OD at 65% throttle opening, then once in 3rd a momentary lift will get the torque converter locked back up and then it will typically either maintain speed or accelerate unless it’s a very steep highway grade. I have never needed to go to wide open throttle in the over 85,000 towing miles we have logged with this 6.8. I am willing to bleed off a few MPHs on long grades to avoid a downshift most times as I like the better MPGs more than being the first on to the top of the hill.
Gears are the most important part of the 2V V-10 4R100 towing puzzle, a good tune with improved shift strategy is second with exhaust improvements third in my experience.
This has been our combo for the past 10 years and about 75K towing miles, from home here in PA it’s been from Canada to FL and as far West as WY and West TX. A well setup 2V 6.8 can be a pretty capable tow rig.

 

My power in my v10 00’ 4.3 265’s ex 205k improved a lot with reman injectors. It had a little ping on towing hills before. Gone now.

this past summer I towed hills all over New Hampshire and Vermont with 2 kayaks and a canoe on the roof and 4 bikes on the front of the camper and an 8k camper trailer. I actually pulled most highway hills at 50-55 mph in second and some long ones in 3rd at 65 and passed bigger newer trucks than mine. I was amazed. Sailing around $200,000 truck and trailers with my $3800 truck and $3800 camper 20+ years old.

never use cruise, anticipate hills, manually downshift before the computer says it should and don’t be afraid to let the thing sing at 3600rpm in 3rd all day. I never pulled hills at more than 3/4 throttle.

 

To bring this up to date with my debacle. -- Changed the oiled air filter back to a factory Motor craft paper - np improvement.
I had convinced myself that maybe?? the previous owner had left an economy tune in it, so I had the ecms reflashed at a Ford garage. - No improvement. The service tech said he couldn't see anything in the control system that had been monkeyed with (aka- tune) He did recommend pulling the cat and seeing if it was plugged or "loose". Said they had seen these truck where the ceramic cat had loosened and when going uphill the block would slip to the back and impinge airflow thru the cat. Sounds like a longshot but. I am not convinced a tune would significantly change , as you can find detailed info online that these are really snake oil fixes and nobody produces real before/after Dyno results...
I have pulled our camper on 3 trips this spring and it sucks. To the point I think it is dangerous towing on the interstate roads. I have to pull these short steep (for the east coast) hills regardless of which direction I head.., Last weekend came up seven mountains east of State College for those who know the area. It is a 5 mile long pull at a 6-8% grade. Hit the bottom at 75, crested the top at 40 floored. Truck has long tube headers, and I changed the gears to 4.56. It should pull our 6500# camper easily up any hill in the east, not puke out like it does. Engine runs smooth as silk and I hate it that I can't get it where it is tolerable. Don't want an oil burner, and hate to drop the coin for a Godzilla. My chebby 5.3 and wife's expedition 5.4 both with 3.73 gears will out pull this slug.
Plugged cat??

 

I had a 2000 SC DRW 2WD with 4.30 gears that we bought new and we pulled a 16K 5th wheel. The only mod was a Banks Cap Back Power Pack that came with a oversized KN style filter and filter box that was on it the rest of the time we had the truck. It wasn't the speediest truck on the road but it got the job done for 13 years and 130K miles until the transmission started giving up. The transmission was the weakest link in the truck and the biggest drawback when it comes to power. Checking the converter would be worth a try but I would also replaced the plugs with Motocraft and replace the boots with a quality ones. And at the same time take a compression test. Pay close attention to #5 and #10 plug because they are a SOB to get to and sometimes are over looked when being changed, the V10 will still run smooth even with a questionable plugs.

Denny

 

Absolutely check if that cat is clogged. Disconnecting the header(s) from the y-pipe should be a pretty simple check (maybe have to wire up some support for y-pipe). On that note, curious if your V10 has an 02 sensor aft of the cat.

Also, when's the last time the fuel filter's been changed? Being a creampuff (75K miles) is a good and a bad thing. A lot of downtime isn't good for the fuel system / filter either. If either of the above don't help performance, I'd check the fuel pressure too. Really believe it's going to end up being something simple (especially now that you have a known tune / baseline)

Unloaded, does it run ok thru the rpm range? Or does it feel like it's laying down past 3K rpm? Mine pulls strong from 3K on up (it's linear, but strong) with your same gearing.

 

I had a plugged cat on mine when I got it 10 years ago. It drove fine and idled fine on test drive but would struggle with a load. The honeycomb material was broken in between the ends. A visual on both ends of the car looked like new. It ran much better after gutting it. The exhaust smells though.

Last year I finally swapped in reman fuel injectors. I always had a ping on high load situations towing long hills. There is only special bench testing for injectors. Mine still opened and closed but I assumed they leaked when closed and did not flow max when full load. Night and day difference. I tow 8k camper and a pile of kayaks on the roof of our excursion up many highway hills in Vermont at close to the speed limit in 3rd.

I don’t think anyone should use cruise while towing unless it’s the flats of Kansas. Getting the downshift early is the key to keeping the rpm’s in the power band which is anything above 2600rpm. I anticipate with OD turn off and leave it off for most country hilly roads. Most times on big country hills I will let off and manually shift to second and keep the rpm up around 4k.

I have 4.30 and stock tires, no tune.

If you find a good shop (like older ex-ford tech) they might be able to interpret the live data and see if the computer is trying to correct for lean condition under load.

my truck pulls very well for a $3800 purchase 10 years ago.

 

Well now, two weeks ago I had the local Ford dealer reflash the ecms back to original specs plus any updates. (Only cost $80)
Made one 100 mile trip and although markedly better - must have had some crap economy tune in it - still not what I expected.
So I followed several folks advice/hint/idea that the CAT was plugged. Just took the whole section of pipe off and laid it on my workbench and preformed surgery on it. Just cut a window in the housing. Front and rear honeycombs looked fine, middle one was loose and over halfway plugged up with what I presumed to be crushed CAT material. Removed the whole mess and welded it back up. It is loud, probably too loud to keep it this way but just now pulled into a campground after dragging the camper about 150 miles up/down/up/down northern PA goat paths including I-80. Totally different truck. I was able to pass trucks going up Rockton mountain on 80 (around 111 mm) and actually gained speed till I was running 70 mph. Gears, factory tune, and a removed cat make me want to keep this behemoth now. I will probably put an aftermarket CAT in it as it is straight pipes headers back, and the CAT did tone it down a bit. Not sure what it will do to mpg but sure can't hurt it any. WIll see on our return but super pleased overall now after it struggling from the time I got it.

 

Glad you got everything worked out. Those cats are a downfall on these trucks. I have a 2002 F350 CCSB V10 AUTO 4X4 with 3.73 gears, 285/75/16 tires. Truck was not what I expected when purchased with only 111k on the odometer in 2019. Found out in PA(I'm in the northeast) any trucks registered over 9k pounds are emissions exempt. I pulled the cat completely. Night and day difference. Definitely smells like it's running rich. But fuel mileage hasn't suffered and more low down torque when pulling. I've been towing a 7k travel trailer with ease.