There has been the odd sticky brake caliper. Way want to check hub temps after you drive a while.

 

Definitely hand calculate your mileages before making a formal complaint. I've found the dash computer to be a decent guideline, but not accurate for conversation. Mine is always 4-6 liters out on a fill, comparing what i add to what the truck says I've used. Good luck, i hope you get some resolution quickly!!

 

Yes, I'm hand calulating the mileage and yes... the indash is a bit "happy". I'm usually 1-1.3mpg on the low side of what is being displayed. The fault appears to be in the calulating fuel used portion of the computed calculation. As a first time diesel owner I "probably" cried wolf too soon. So for now just gonna keep an eye on things. I suspect a big portion of the "problem" is having access to information I've never had access to before!

Thanks for the feedback!

 

So, I am guessing then I have an issue. Reading these posts, the 9.9 mpg I got on a 150 mile trip is not normal. I have a 2013 F350 with the 6.7 and a 3:55 rear end. I was towing my 5600lb trailer and it was in the mountains. To top it off, to be legal, I was limited to 55 mph(stupid CA split speed limit). no active regen that I saw, and no warnings. I do believe it is time to replace the fuel filters, as it is past the interval(I don't know when they were changed last, but I know it has been done at least once). So I will change the fuel filters and see if that is the issue. The first time towing I averaged around 13-15 mpg, and that was in OR, where I could do highway speeds like everyone else, so my RPM were up around 17-1800 or so and doing 70 mph.

 

If I hook a trailer up, I get 10 mpg. doesn't seem to matter if it's empty 5,000 lb dump trailer or a 13,000 GN horse trailer

 

Same as above. If I hook up my trailor and drive easy at 55 to 65 I get 10.5....if I'm driving around town at 40 to 45 empty I get 18. This is with 4.30 gear. If I'm driving aggressive empty i get 11. These trucks are heavy and require lots of fuel to get them moving. If you have a lot of stop and go your mileage is going to suffer no matter what superduty configuration you have

 

Ambient temperature and wind speed, are the biggest factors that I have noticed.

 

Thank you all for the input. Maybe it is normal, I wouldn't know, as I have only had the trailer on 3-4 times. It is time, however time to replace the fuel filters, as it has been 47K since I bought the truck, and there is no telling if LITHIA Ford changed them before selling me the truck as a "certified used" vehicle. 4 ply tires, clogged egr cooler, only one key......

 

I used to get 12 MPG with 8k tagging along at 55 MPH but it's 10 now since 12 MPG is my normal.

Also, the fuel system is important to maintain on this truck. I change my fuel filters between 15k-16k. The Shell station I was using when the truck was new for the first 15k had crap fuel and the DFCM filter had a decent amount of algae.
I then switched to another Shell and the filters were clean after 15k. I did further experiments on the third and fourth sets but the end results are to change the filters because you just don't know what stations have in their fuel tanks!

B rated tires on an F350!? What was that dealer thinking? This is how the uninformed lose their life and potentially impact others on the road.

 

Don't forget about traveling speed.

I was on a camping trip back on Memorial Day with a friend that said he got 12 mpg pulling a similar size and weight trailer as mine. He has a Nissan V6 but still I wasn't convinced that kind of mileage was obtainable. On the trip down I had 9.9mpg on the instant mileage reader with my cruise control set at 70mph. On the way back I followed said friend back home and maintained his speed (60-65) and the instant mileage reader when up to 11.5mpg.

 

Yes, I get the best mileage when not towing at 55 MPH. But who wants to do that !

 

Justin,

it is really impossible to tell with just one trip of 150 miles. There are so many variables- wind speed/direction probably the biggest, followed by speed, and how long it takes to get both engine and transmission to operating temperatures. Seems to love 60 degrees, but colder than 40 and the air is a lot heavier producing more drag at every speed. Given your description two others jump out at me.

With that rear end and a light load in the mountains at 55 mph, I suspect you were lugging the engine and you get less efficiency that way. Fine on the flats with a load, in the hills without, but not with a load in hills or mountains. Try locking out 6th gear. Try using tow/haul for a bit and see how that shifts, and more importantly, downshifts going up the hills. Once you see what it does, you can continue to use it or just manualy replicate with the manual shift button.

The other is a regen during such a short trip that is easily missed- those 20 miles/minutes at 9 mpg empty don't impact much overall when they are once every 500 miles, but if you were in regen for 20 of those 150 miles, it exerts significant downward pressure on average mpg.

Even mpg by tankfull can be misleading even if 100% same speed and driving conditions. You end up having only one regent per tank on ocassion but most times it is two, and if city driving maybe 3.

Try leaving trip a alone forever so you can see long term fuel usage. I have had 4 of these dually trucks, all geared 4.10, 4.30 and 3.73 for heavy loads, putting about 100k mikes on them before trading up.. Yes I occasionally have seen instant 20mpg for 5minutes at a time on the flats empty, and 17 mpg empty for 200 miles on the flats empty. I plan on 9.5-10 when towing. My highest mpg in a straight 500 mile day run was right at 11.8. But I have also seen 7.5 mpg fighting headwinds out west. More than 60% of the time i run with 10-17k pounds hooked to the truck. Full 100k life average has been between 12 and 12.5 mph for each of these vehicles.

 

I'd just set your computer to another screen, and quit watching it. Hand calculate your mileage for awhile, then maybe flip back to the mpg screen, and see if it matches. If it doesn't.....then you have a problem/issue.

 

 

John,
I just completed a trip to Frisco and back, with trailer attached and to add another variable-hauling water. A family member ended up in the hospital that cancelled a perfectly good hunting trip that required the presence of both my younger brother and I (I'll spare you the details). I did use your advice and locked out 6th for the trip down, as we were forced to detour from HWY 97 to I-5 (I-5 was closed betwixt Mt.Shasta and Redding due to a wild fire) and take CA 299 to CA 89 and run over the back side of Lassen on CA 44. I averaged 12.6 MPG with 6th locked out in the mountains and around 13.5 on the freeway. Tow/Haul was engaged from the moment the trailer was hitched up. My rule of thumb is that any trailer with a brake incorporated- Tow/Haul is engaged regardless of weight- my boat trailer doesn't have a brake incorporated in the trailer and if I have to hammer the brake, I don't want the trailer trying to come around to kiss the front end. My brother drove about half the trip, mostly all the heavy traffic- he is a professional truck driver and I think he fell in love with with the engine brake function and the easy towing of the truck(strange thing-trailer actually towed better with the fresh water tank full-but that is a story for another forum). On the way back up we averaged 10.5 MPG. So in conclusion, I don't think I have a mileage issue at all. I do want to thank all of you for the input. My mileage will vary, but if I keep the to a reasonable maintenance schedule for the fuel filters, it won't vary so greatly that I have to spend lots of dollars to correct the issue