Running a 2016 350 superduty.
I watch the fuel efficiency fairly constantly kind of a game to keep getting as high as possible.


Something strange keeps happening. at random I will go on hiway running around 19 mpg for some time then all of a sudden it drops to around 12 mpg. nothing changes and it will stay on 12 mpg or so for around 20 minutes then come back up to the 19 arear.


any ideas.
it does ot seem to co inside with the def cleaning or road surface or weather conditions.










Cheers for any thoughts.
SteveP

 

Are you sure it isn't in regen? That is exactly the behavior for a regen. The message that appears on the dash is only for a couple of seconds and very easy to miss. You might try hooking up a OBD scanner such as ForScan or Torque Pro to monitor it.

 

Steve:

Welcome to FTE! Great group of people in the 6.7L section.

Sounds exactly like a normal regen.

bruce...

 

Thanks guys I will try pay more attention to the regen. that's crazy that is F@#$ up your mpg so much.
Im doing a really long drive next week so should be able to pay special attention.


Cheers guys SteveP

 

Thanks guys.
I'll keep a closer look at it. that's crazy a regen drops the mpg so much. guess I got a lot to learn about these
Cheers STeveP

 

There are some anecdotes that the new PCM flash (which corrects the rare "jackhammering" during regen) also uses less fuel during a regen. I'm thinking about having it done just for that reason.

 

Mr Rat whats the PCM flash ?
cheers mate.

 

PCM flash is a dealer procedure that reprograms the engine controller firmware. They update this all the time, the latest one is supposed to change the regen from left bank only to both banks and less fuel.

 

like when did this come out?


Fert

 

Like a few months ago.

I got it done and I like this strategy better than the one that came with my 2015.

 

is there a PCM number for this upgrade? or however it is kept track of by ford so I will know what to ask for specifically when I goto ford.


I hate hate hate the dam regen, but gota wait till warrenty is up


Fert

 

I would love to know how you guys are getting those impressive mpg numbers. My 2015 F250 cc PSD 4X4 averages 15 mpg according to the dash monitor. While on vacation, we towed our 10,500lb trailer around 1500 miles with some 6% and 8% up and down grades in southern Utah. A lot of flat land also. I averaged 10.8mpg which I think is still respectable for this combination. I have not checked the mileage the old fashioned way of miles divided by gallons yet.

 

The 4x4 is hurting you some. My '15 seems to get around 19 conservatively driven on the freeway, and 14 with a large camper loaded even on mountain passes (again, conservatively driven) - about the same as my '99 7.3L. 4x4 has a bit of extra mechanical drag and is about 3" higher. Driving 80 mph can have an effect too .

 

Yeah but I didn't think it would hurt that bad. I will have to pay a little closer attention to it. This truck came with continentals on it (hi way tires on a 4X4??) which I replaced with a set of toyo AT2 which didn't help either.

 

Get ready to be depressed when you check the mpg "the old fashion way". The Lie-O-Meter is about 1 to 1.5 mpg high.