It just doesn't work that way in real life. I've known a few people with aux OD units and none of them report a significant increase in MPG. Any increase they see is more likely due to having more gears to get to hwy speed.

The key here is 'It takes a minimum amount of fuel to push a vehicle down the road at a given speed'. It will be the same amount of fuel at 2100 rpms as it is at 1700 rpms. I can tell you that towing with 4:10's and a 6spd (my dually) is waaaay more desirable than the 3.73's and 4R100 (my Excursion) and towing MPG was almost identical.

I put 120k miles on my Excursion and the best MPG I saw was with stock tuning and 265/75/16 Michelin LTX's. My now ex-wife could squeeze over 20 mpg out of the big dinosaur driving it like a granny and staying under 65mph (often cruising at 60mph... ) I could never drive like that and generally saw about 15mpg with 285/75/16's. Of course, I was burning free high-cholesterol fuel and had little regard for MPG most of the time. At 22k lbs GCW with Toy Hauler in tow I was generally around 10mpg - but I was known to put the chip in my hot tune (324 RWHP ) and drop the hammer climbing grades if I was in a hurry!!! I estimate I was in the gals/mile category at that point... (Btw, it takes good tuning and a BTS transmission to do that with confidence )

 

I think that what Tugly mentioned about checking the ODO against the mile markers is the best way to verify your mileage readings. Those markers are surveyed within less than a foot error.

 

Started doing this on a 10 mile stretch of the Turnpike. But I have 3 girls with me and there was a rest stop, LOL!

I did, however, uncover some data showing my EBP all erratic and such. I started a new thread about it here: https://www.ford-trucks.com/forums/1...l#post15449864

I'm thinking we find and fix that problem, we'll fix this MPG problem

 

Hey Mark, can you give a clarification here?

I found this in my manual:

This seems to contradict what you said about not having learning transmissions in the Diesel Excursions

Did Ford have generic, one-size-fits-all manuals, listing something that isn't in my model?

Is this some special version of Excursion that has the adaptive learning?

Or is the info in the manual just dead wrong?

I'm the guy playing catch up on this stuff, so maybe you or someone has addressed this conflicting info already, but I'd sure appreciate if you'd do it again

Thanks!

BTW, this was in the main owners guide, not the supplement, which I don't yet have electronically.

 

Yes they did.

Yes there is. The Excursions with gas engines had adaptive learning software for the 4R100 transmission.

It is right for 2/3 of the engines available in the Excursion.

 

Thanks, Mark. That's clear enough, even for me to understand

Now I realize the emphasis should have been on "diesel" doesn't have the learning transmission instead of "Excursion" (I might have assumed that last part )