Warrior3313

Hey. I have a 2011 FX4 ecoboost crew cab and I have not been getting the same mpgs that people talk about. Now I have done some things like put the autosprings level kit on and Toyota MT 33x12.5x20 on but I have read plenty of others who have done the same who get better gas mileage then me. I recently went up to Vermont round trip about 600 miles and averaged about 13.8-14 mpgs. Now I am not sure whether it is because I have not calibrated the true to the newtires yet or what. I have read something about the trailer brake control disabling it and getting better economy but that didn't seem to work either. Crushing on the highway at 60mph I was getting 13.9 about. That doesn't seem right to me at all. I was wondering if anyone else may have any ideas. Could it be a software issue or a transmission issue? Has anyone heard of other problems like this?

Please help me out here as I am at a loss. I know the mods that I have done don't warrant this bad of mpg and even before the new tires I wasnt doing much better.

zitterich246

If you havent calibrated the speedo for the tires your mpg wont be right. Also the cold weather along with winter blend fuel will affect it. The level kit also somewhat affects the aerodynamics of the truck. Ive lost about 2 mpg since the weather started getting cold.

gimmie11s

^^^ what he said...

You need to hand calculate a couple tanks and report back (tire size change is making your computers mpg calculations incorrect) ....

The tire upgrade is is going to hurt your mpg's but not to the tune of 5-6 mpg.

TJPlatinumEB

Don't forget that in addition to your speedo being off by a few percent, your actual miles driven will not be right as well.

Factory tires are roughly 31.91" tall and in upgrading to 33's you have effectively increased your tire size by approximately 3.4%. This is of course how far off your speedometer and odometer will be also.

You are actually going 3.4% FURTHER in miles than you think you have. This of course throws off all calculations done by the computer.

Do a few tanks of hand calculating and be sure to add that 3.4 in there when doing so. Take whatever miles it says and multiply by 1.034 to get actual miles and then divide by the gallons filled up. With a 20 gallon fillup that can sway the mileage by a full .5 and of course more as you go up.

However, with the tires and winter fuel, I wouldn't expect much better than 17 or 18 on the highway for that truck. If you figure in stock form you could get say 21 at best, knock a good 2 off for the winter fuel and then another 1 at least for the tires and lift. You've gotta remember that the additional weight of the tires, size, tread pattern, and of course increasing the height of the truck with both the tires and level will effect that too.

Warrior3313

Yea I mean I know the tires throw the speedo off but I wouldn't think by 4-6 mpg. I was wondering of anyone has heard of any issues with the transmission or maybe a software ecu problem affecting the mpg from the factory?

P150

In any other full size truck with your setup, you'd be getting 10-12 mpg.

ken75ranger

Sure it would.
Like the other guys said. It's a few things.
1- The speedo is off so your mileage is off.
2- your truck is now taller. Airflow underneath it lowers mpg
3- heavier unspung weight from the new tires lowers mpg's

You can get rid of number 1 if you try.
Get it reprogrammed or use a gps unit to find your actual miles and hand calculate the mpg's.

KGSloan

your numbers are right in line with mine as i have not recalibrated my speedo

my tires are ~5% taller than stock, so whatever my mpg display reads i have to add 5% to in order to get the real number. i am generally between 13.5-15mpg on the display, which is actually 14.2-15.8mpg. pretty respectible for a lifted 6,000lb truck with retarded heavy 10-ply mud tires. for example, my buddy with a 6.0L chevy and a lift with similar size tires gets from 9-11mpg unloaded.

Warrior3313

Yea I guess so. I ordered the AFE intake today to get some better air flow and hopefully help out with the mpg. I am also waiting on Mike at 5star tuning to get me some tunes for this truck. I know all about the bad mpgs as my last truck Was the Ford Raptor. I had as much done to it as you could with out turbo or supercharging it. I was pushing 500Hp on it so I sold it actually mad a profit and bought this as my new project vehicle. My raptor was getting 8-10 mpg and 12 highway tops. That thing ripped. Miss it a lot.

Just found it funny that even before my mods I was only making about 14.5 mpg around town. Oh well gotta pay to play as they say.

matt99

Pics or it didn't happen!

And those things shouldn't affect your mileage by 6mpg. My dodge lost less than that with 10" of lift and 37/13.5s before a gear change. Try a GPS unit to track distance and manually calculate