Do you think it could anything mechanical, plugged filter, etc?
Do you think the DPF delete would make any difference?

 

There is always the possiblity that a mechanical issue is present but doubtful.

Big tires create and fair amount of drag. I would assume they are of an agressive tread pattern as well.

How are your regens? How far apart? Tail pipes clean?

A programmer and a DPF delete may help some with the mpgs, maybe a couple but then you put your warranty at risk.

Another consideration is the towing, you don't want to add too much more power when towing as your egt's could become an issue as well.

 

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Hey,
I have a 2010 F250 6.4L, 18,000 miles total, DPF Delete, EGR Delete, CAT Delete, Spartan 210+ HP tune using Phalanx Tuner, 3:55 rearend, Stock Continental 32.5" tires, just drove it to Dallas, TX and back, total of maybe 1,400 miles. Runs great, sounds great, got 21.73 mpg at 66 mph turning 1,700 rpm for 294 Sm. Personal record on the fuel mileage for this truck. Not surprising, pushing it up to 80-85 mph, turns a little more than 2,000 rpm, fuel mileage drops about 25% to only 16.1 mpg. I guess that's what happens to brick walls hitting too much wind. At 70 mph, I get right at 20.0 mpg, all of this hand-calculated at the gas station pump, of course.
All these figures are empty truck, no towing.
I've met others getting better mileage, but, my 6.4L is not even broken in yet. Expect by 30,000 miles it'll be broken in.
As for Ford Powertrain warranty, the three (3) Ford dealers I've spoken to regarding engine mods tell me Ford has to definitively correlatate an engine component failure to diagnostic proof of overtemp or overboost. The fact alone that you mod the truck is not grounds in court for voiding an entire factory warranty. Cause and effect must be proven to effect (contract law).

– Chuck Smock, Major, USAF, Columbus AFB MS