Dealer Flash causing lower fuel mileage

[Alan Reagan]

Took the truck in for the free oil change at the dealer and when I picked it up the dealer said there was an ECM update. On my second tank of fuel and my highway mileage is down 3 mpg. I'm going in tomorrow to see what they have to say about it. Anyone else have this problem?

 

[Larry Willard]

I've had several updates on mine but no noticable change in fuel mileage. Did they put in synthetic oil like the factory fill?

 

[Alan Reagan]

Larry, Probably not synthetic. I didn't think about that. I'm going down there this morning to talk to them. This a significant drop in mileage.

 

[Alan Reagan]

I talked to the dealer this morning. The flash was an emissions flash. The mechanic said the mileage will come back after about 5K miles. All of the adaptive tables were reset and the ECM has to learn those values again and it takes a while to do it. I have pretty much covered all of the bases with towing, empty, interstate, two lane driving, etc. Time will tell.

 

[sag2]

This is what it covers (besides a couple of false CEL's).

In addition to addressing the above DTCs, the following powertrain system
improvements/enhancements are also included in this software release.
· **68RFE Transmission Shift Quality Improvements for low speed First to Neutral and
Neutral to First (Garage Shifts).**
· **Charging system improvements for single alternator applications (Changes the
cutout threshold from 600 to 500 RPM).**
· **Diesel Exhaust Fluid (DEF) system calibration improvement during Stationary
Regeneration.**
· **Cold idle speed stability improvement.**
· Charging system improvements for dual alternator applications.
· Torque increase to 865 ft/lbs (D2 vehicles equipped with the Aisin transmission
sales code DF2 only).
· Fuel Filter Minder calibration changes.
· wiTECH Fuel Pressure Override and Fuel System Run Up test improvements.

 

[Alan Reagan]

It has made a significant improvement in the transmission shifting. It's a lot smoother now. It's like my '11 was.....I can hardly tell it is shifting.

 

[Deleted member 995608]

The mechanic said the mileage will come back after about 5K miles.

At 3 miles less per gallon, I'd be a little upset if had to wait 5k miles for my mileage to come back. That's a lot of fuel.

 

[Alan Reagan]

I'm not happy at all with the mileage drop. They have had several complaints about the situation. However, they can't go back on this flash. I'm actually seeing some improvement already. I am up almost a mile per gallon from last week and it's climbing slowly at a tenth of a mile per gallon and I'm on my second tank.

 

[Alan Reagan]

Well it's back. It has taken about 3K miles but I took a trip this past weekend, not towing, and the mileage was up to 23.2 mpg when I got home. I refueled this morning and hand calculated and it came out to 23.4. I guess the adaptive tables take a while to repopulate. My around town is actually about 1 mpg better at 20.1 over the last two fill ups. So I'm happy again. The truck did seem to go through at least two regents after the update and that really sucked down some fuel. During the second one, I got on the interstate, set the cruise at 70 and could tell when it finished because the mileage started ticking up and continued improving through my trip this weekend.

 

[Doubleclutch]

Thanks SAG2! Can I wishfully hope that the 865 Tq number can be added to the 2014/2013 trucks running AISINs?