So I pick up my '15 24 Dec, as of today I have 4500 miles:

1st tank barely got past 10 mpg

2nd tank gave me hope and showed up with low 13's

3rd tank and beyond, I watched the mpg counter drop 1 0.1 at a time till I am at 10.3 overall mpg as pulled from the AB trip meter, not the instant read.

DEF, good lord Roy in his best days could not keep up with the way its sucking down DEF. So far its drank 10 gal that i have put in and the screen is showing 'Less than 1/2" full. I can add another 2.5 for a grand total of 12.5 gals of DEF ++ what ever was in the tank when it was delivered, even if it only had 1/2 tank (I checked when I picked it up and it said "Full" that would bring total DEF to 14.5 gals in 4500 mi! to Roy

First dealer I took it to called mpg/DEF use "NORMAL" and wrote that on the ticket when I picked it up.

Meet with Service Mgr of Ford house that sells LOTS of SD's here in Ranch country. He looked at me and Normal, NOT!!!

Here is the initial take on this: They have found some of the later deliveries SD's get locked into a learn mode and just 'never learn'. This uses a lot of fuel and DEF to boot.

He then asked if it ever suddenly seems to explode with power. I said YES and I am talking shove you back in the seat kind of power. He said that the engine mgt sys is supposed to meter the power so as you don grenade the trans or smoke the tires from a start and this is another indicator that my computer system is not working correctly. So it went the shop today, told them to keep it as long as needed. He said he might kick this up to Ford Engineering and get their take on it.

I post this in the event some other on here are seeing the same poor mpg/DEF consumption.

 

Thank you Don. This just shows that a second opinion on something this important is worthwhile. I hate when I have a problem & some "know - it all" has the simple but useless response. Thank you & please keep us posted.

 

I've noticed my mpg and def consumption is erratic but there are so many variables it's hard for me to reach a conclusion. Is my build date in your zone of maybe weird computer stuff?

 

And I am not getting "great" mileage either.....instant now shows around the 14 mark. But the DEF usage is in the ball park of what others say they use. I have just shy of 9000 miles on now, and I broke thus puppy in towing my Raptor from ND to AZ, plus some other trips around AZ with either the Raptor or the 38' GN.
So, without going out and looking, I am guessing the total towing miles on mine to be right around the 2500 mark. And the AB trip meter shows an over all average of 11.6 I think. But, I can never get the fuel mileage that other people seem to get, either......so I just write it off that I must have more fun!
Hope you get your problem resolved!

 

I am at about 5,500 miles. Just filled the DEF tank for the first time. Some hwy miles.....lots of town miles. over all....about 14 miles / gallon. Now with the summer blend of fuel, I am seeing this increase by about 1.5 - 2 miles/gallon.

Have not towed the Monster yet.......

 

I think it's the newer firmware, which probably has some similarities between the 2015's and the older years. My 2011 is awful after this latest "emissions" update. 12mpg is normal now empty, which used to be my towing mileage.

 

What waz the build date? It should be on the sticker on the door jam or show up in engineering test mode.

 

I picked up my 2015 F350 with the max tow option on April 11 and it was built on March 16 according to the dealer.


I noticed that one of my spare DEF tanks in my shop had a small pin hole in it so at about 3,000 kms I poured it into the F350 but it would not take the whole two gallon jug but took at least three quarters of it.


I have done maybe 500 kms of towing with this truck and yesterday at about 4,400 kms I got a "805 kms of DEF remaining" message. We were about to head up to my in laws which is an 800 km round trip journey so I grabbed another two gallon DEF jug and poured it in. It too started spitting out with a little over 3/4 of the jug poured in. I don't understand why if there was only 805 kms of DEF remaining I couldn't empty an entire two gallon jug into the DEF tank.


Is it possible the DEF remaining calculation is dynamic? The reason I ask this is that for the first time yesterday I hooked up my 15,000 pound fifth wheel travel trailer to the F350 and hauled it about 20 miles to my buddies shop to have all the tires of the trailer replaced. So I got this low DEF message after towing for about forty miles. If the computer thought I was going to continue pulling this load would it then have decided that I only had 800 kms (500 miles) of DEF remaining if I continued to tow? Perhaps that is why I could not get the entire two gallon jug in.


This DEF consumption definitely is much higher than I had with me 2012. If I did no towing or only say a 1,000 kms of towing I could go 8,000 kms between oil changes without having to add any DEF. If I did a lot of towing between oil changes I would sometimes come up 1,000 - 1,500 kms short and have to add DEF.


With less than 5,000 kms on the 2015 and less than 500 kms of towing I have already added more than three gallons of DEF to the 2015. Unfortunately I did not check the DEF level when I picked the truck up from the dealer so I don't know the starting point.


Another difference is that on my 2012 the low DEF warning would pop up with around 1,300 kms to empty in the display whereas the 2015 gave no warning until there were just over 800 kms of DEF remaining.


So far I am actually pleasantly surprised at my fuel consumption. With the max tow option you are forced into 4.30 gears while on my 2012 I had the 3.55 rear end. With the 2012 I was getting around 19 mpg to the imperial gallon empty and about 13 mpg when towing heavy at around 70 mph. No real towing data on the new truck yet but I hand calculated 17.6 mpg on the first 1,200 km trip I did with the 2015 which I thought was not bad for a brand new truck.


Regards,


Lauren

 

I forgot to mention that my 2012 was a SRW F250 - not a dually.

 

Similar experiences for me, I will occasionally get the low def warning only to get 2-4 gal of def in it when I fill. I'm about 50% convinced that the venting of the tank, especially to fill, is poor design. If I work at it, move the truck around a bit, I can force to almost get 5 gal when I fill it. I suggest we all pay close attention to this as it may be the whole issue here, just not getting it full.

Those of you with less than 10,000 miles on your trucks are really just touching into the break in period for the exhaust systems. I can comfortably suggest that no consistent behavior from the exhaust system will happen for you until you get some significant miles on the truck. 10 or less dpf regeneration cycles is just the beginning of establishing the baseline parameters for your style of driving/duty cycle.

Just my opinions of course. My mpg towing varies from 13 to 9.0 and the changes don't appear to be attributable to my speed, weight, or weather conditions. It feels random to me so I'm struggle along with y'all to figure stuff out too.

 

I took delivery on 24 Dec, the truck arrived at the dealer the night before. My build date was on or about 2nd week in Nov, I will check, truck is in the shop now.

I am going to concur with the Svc Mgr in his thoughts on what has happened. Its a software issue. This is becoming more and more of an issue across all cars. Engine mgt is no simple process and throw into the mix managing HP/Torque to keep from sending your trans and axles to the junkyard, emissions etc then it really gets complex. But that is doable from a Software engineering viewpoint.

The problem is unless the software does/does not execute a command properly and that coding does not trigger a failure code then the dealer will often just tell you its "normal. because there is no fault code" Mechanics and dealers are falling into the trap of no fault code therefore no problem.

There is no fault code for poor mpg and using too much DEF. Its my guess we only have fault codes for when something goes wrong or its lower limit, not when it exceeds its upper limit.

Don't refill the DEF and you get plenty of fault codes, but if its using to much there is no fault code for that and there should.

Almost all system functions operate within a set of parameters, me thinks some Ford engineers need to get a better understanding of critical systems development.

 

My '15 F350 with a 3:55 rear-end was built on 11/18/14 and I took delivery Dec 20th I believe. Like "Ruschejj", I find that my mileage varies for reasons, I can't explain that do not seem to be related to speed- but could be prevailing wind related. I have just over 10,000 miles on the truck so far.

My overall average is 15 mpg including towing a mid-sized enclosed three place snowmobile trailer about 2500 miles.

Overall though I am happy with the mileage I am getting. I also find that my def useage is less than I experienced with my '12 F250- but that is a subjective determination.

Mike

 

I think the DEF must at times Crystalize and block off the vent tube. Sometimes I would be below 1/2 tank on my 2011 truck and still could not put a whole 2.5 gallon jug in. Sometime not much of the jug at all. Then a day later, you can fit the whole jug in.

My current 2015 truck took 2.5 gallons of def at about 3500 miles. But 1500 of those miles had a trailer hooked up behind me. It's pretty easy to see EGT temps of 700°+ when towing my 4 horse GN trailer. So I expect to use DEF when towing.

 

I'm at about 3600 miles on my '15 and my hand calculated (ok not hand, really Excel) combined mileage is 14.57mpg for the first 3314.7 miles. Haven't filled the tank yet from this weeks return trip from the gulf coast.. so no joy on that mileage.. best tanks so far 16.86 empty all highway and worse 9.81 towing 12,500 5th wheel into a 20mph head wind..


DEF usage is suspect because I'm pretty sure the dealer didn't fill the tank.. Less than 1/2 warning showed at 2280 and it wouldn't take but 2 and a bit gallons.. Put the rest in this weekend.. Got the trip B going looking for DEF mileage so I'll know soon if 2200-2300 is the norm or not.. I suspect that after the break-in mileage and DEF use will get better.. I know that's been my experience of the last several trucks..

 

17 Oaks. I have made the fuel mileage complaint too... But of course I get the it is normal response as well. After initial reports that the 2015's got better mileage and had a little more power I am disappointed with actual results. I, too, all of a sudden notice the truck will have a big burst of power. And then like last night, it seemed OK, but not great. This was tough to judge in the winter when the tires slip on the snow/ice, but now that we are back to dry pavement it is noticeable.

I am reserving judgment until my highway drive to Fairbanks and back in a few weeks. DEF use seems higher than my 2011 was and when I took delivery and drove the 2015 home, I purposely tried to put DEF in and I couldn't put any in. I was going to just make sure the DEF was topped off before my trip, but now I will top it off (again) and bring DEF with me... Being in the wilds of Alaska and seeing 500 miles to idle is going to be a pucker factor I don't want to deal with.

If you figure something out, please let us know. It would be nice to be able to have the tech here call in and have a reference. The techs here really want to help - so if I can point them in the right direction I know that they will listen. This is assuming I don't see the 17-18mpg I should be seeing on my trip. I have done that run in a SD in the summer up here before, so I know what to expect.