It's not the T/H setting that changes the calculation (but that's not a bad idea!). It's in the setting menu of the center display. It appears that the DTE calculation is a combination of fuel tank level, historical MPG with an added bias on whether you have to DTE setting set to "Tow" or "Normal", telling the computer how you intend to use the truck on the remaking fuel level. As I said earlier, my 2.7L truck works as expected, the 3.5L Eco, not so much.

 

But, if you haven't run in T/H you don't have an average T/H MPG. So, there must be a default T/H MPG in the system. Otherwise, when you change the DTE calculation to use the T/H average it wouldn't be able to calculate.

Perhaps the default T/H MPG is unrealistically high, so when I changed DTE to T/H the result was actually higher than Normal?

 

Yes, I just made a 3600 mile trip in T/H.
It does it regardless of the transmission mode.

 

Maybe be it checks past mpg based on what trailer you are towing at the time. So if no history of towing a/this trailer it goes with the default factory one. But once you start towing a trailer it then uses what you are getting now figures.

 

That's pretty much what I'm guessing, although I forgot you can name the trailers. So, if it was programmed for it the average MPG could be recorded by trailer and used to calculate DTE. However, then it would have to handle the situations where you run in T/H but aren't connected to a trailer. So, I'd bet it just records average MPG for any time you are in T/H and uses that to calc DTE.

 

Even Fords engineering wouldn't be that dumb to use the transmission mode, it's got to use what mpg you got before while having this trailer hooked up and by knowing what trailer you have hooked up. The travel home one or the 12' boat one. To be of any useful value to us. I think when you pick tow DTE it looks into the history of what it got before with this trailer. And if no history just starts with the default one.
It should make no difference what transmission mode you use.
But even than it would have to strongly figure in what you are getting in the pass few miles and keep up dating the DTE miles.

 

So, how do you figure in the Tow/Haul mode? You can tow without being in T/H mode on the transmission. Does that make any difference?

And, if you don't have a trailer attached but go into Tow mode for DTE, why does the DTE change?

Note that I don't have any answers, just lots of questions.

 

You change the DTE calculation in the Settings menu on the information display between the gauges.

 

That's my point I think the T/H mode isn't used to figure DTE as it doesn't mater it's the average mpg the truck was getting last time with this trailer, when first asked for the towing DTE. Once you start towing it then updates to what you are how getting. So "At this speed with this trailer on this type terrain you can go X miles till empty". Change any of this and it will have to update to be of any use and I'm sure it does.
As to why not having a trailer attached and switching to T/H mode changes the DTE it's because the different shift points causes you to get diferent mpg. Now as to why it thinks T/H mode is going to get you better mpg,,might be because it hasn't been driven long enough to get a update over the factory default mpg yet.

But what do I know??? I'm still trying to figure out how to get my halo lights to work. And that my cooled seat back shouldn't make my back sweaty.

 

Yes, I've done that. But, the question is whether the calculation uses an average MPG that has been achieved in the transmission's Tow/Haul mode, regardless of whether a trailer has been connected. Or, an average achieved while pulling a trailer - regardless of the transmission mode, Normal or Tow/Haul. And, if the latter, is it just while pulling any trailer? Must be as there's only one selection in the DTE calc - not one for each of your trailers. Unless the DTE changes when you connect/disconnect a specific trailer.

 

Now we would think that it would keep track of which trailer was pulled last and use that mpg if you just switched to towing DTE to get a idea without having a trailer attached. And if a trailer was attached use its history mpg.
But just because we think something should work one way doesn't seem to mater on this truck.
I have three different trailers I'll pull with my truck but so far have not done any pulling. So I have no first hand experance yet.

 

So, what's keeping you? Do it to answer the question!

Seriously, I have two trailers myself and another across the fence I could easily borrow with which to answer the question. But, I've not done that either. Guess we aren't so curious after all?

 

I was curious enough to just go check mine both for this thread and the one I'm going to start about my halo lights not working the way the manual says they should.
So with about 25 miles into a full tank my normal setting shows I can go 670 miles till empty, but switching to tow I can go 740 miles to empty. Guess I should start towing a trailer all the time??? Just makes it hard to park at Wallyworld..

 

That's pretty much what I found - Tow DTE is better than Normal DTE. There must be some default MPG that gets reset as we drive, but when we don't tow it has to use the default.

 

Right,,, the magic EPA ones.