Fuel Milage Monitor

[djp221]

Took our first road trip in our 08 F350 from Oregon to California and the first time we put CA fuel in the average milage went from 15 to 11. I know the computer isn't very accurate but I'm not sure why such a big difference unless I got bad fuel? The other thing the computer did was go all the way down to 8 mpg for about 10 miles and then all the way up to 30 mpg for about 10 miles? Maybe it was calibrating itself? Just wondering if anyone else has seen this happen.
Thanks, Dan

[timid1]

Originally Posted by djp221

Took our first road trip in our 08 F350 from Oregon to California and the first time we put CA fuel in the average milage went from 15 to 11. I know the computer isn't very accurate but I'm not sure why such a big difference unless I got bad fuel? The other thing the computer did was go all the way down to 8 mpg for about 10 miles and then all the way up to 30 mpg for about 10 miles? Maybe it was calibrating itself? Just wondering if anyone else has seen this happen.
Thanks, Dan

I've got a 08 F250 6.4L. I got 18 MPG on an unloaded long haul from Los Angeles to Chico, with one stop a little past CA-152. Coming back from Chico, I stopped in San Jose then drove back to Los Angeles. On the return trip from Chico, I had an extra 50 gallon auxiliary tank in my truck. Truck computer said I was getting 17 MPG, and I never bothered to calculate it out, but I do keep a fuel log and just from recollection, I get anywhere between 12 and 14 MPG around town, and 15+ on long trips (where the engine is running for hours).

Not sure the onboard computer is all that accurate, with or without my auxiliary tank. Other things to consider are climate and altitude--I'm not sure how these affect your economy. And I'm pretty sure you don't have to worry about bad fuel especially if you filled up on the interstate alongside big rigs.

[blackcloud2k]

yes the lie o meter is only a frame of reference... It is rarely accurate. When I was stock I figured what ever it said on average, I would subtract 2 mpg's. Tuned on average I subtract 5 mpg's and most of the time that is what my hand calculated mileage comes out to. Not exact science but just something for reference.

[Escalado]

Its crazy how everyone differs so much. My dash reads as much as 23mpg on freeway trips with the cruise control set. The best I have calculated is 17mpg which im pleasantly suprised about. Stock SCSB with 373's.

[TXTech11]

yea... I can get it to read about 27.5 on highway trips (H&S/dpf delete/intake).... when in reality it's like 14/15 max (mods in sig). Distance to E reads about 800 miles sometimes (I WISH!!!)

[blackcloud2k]

Ive had mine read as high as 56 mpg's, but I was going down hill in cruise control doing 70 mph haha

[DieselFord]

Originally Posted by Escalado

Its crazy how everyone differs so much. My dash reads as much as 23mpg on freeway trips with the cruise control set. The best I have calculated is 17mpg which im pleasantly suprised about. Stock SCSB with 373's.

The 23 is what you’re getting as an average on the highway over what ever the distance it was figured on.

I have a Scangage add on it has a instance update readout, on a downhill totally off the throttle it will post up 9,999MPG for the motor has all the fuel cut off.

On an uphill a good one (6%) pulling my 6K trailer it will post up 5MPG more or less.

After several fill ups and adjusting what the Scangage thinks the total fuel used have found it is pretty well adjusted and the trip feature will display a some what close MPG for the trip.

The only way to get a true number is by filling up to the neck opening and doing hand division for MPGs and this will vary on the highway and city stop and go driving.

My best with my 2007 automatic 2 wheel drive on highway only has been 33+MPG around town this time of year is 16.5MPG

One of the call ups I can display is GPH Gallons Per Hour. In gear with the air on shows .72 GPH and taking the MPH that is 0MPG.

But what ever system one has it will work it all into what ever is displayed and yes the Scangage will show 0MPG, stopped and running.

One way to get a good feeling what you are getting to go set up a fuel log at a site like gasbuddy.com like I use for every fill and it will at the end of year will show you totals, gallons, dollars and MPG for the year.

[aquamans350]

If you never reset the LOM, it appears to be a rolling average of the last several full tanks of fuel, but there seems to be some interpolation or extrapolation that skews it. I'm still bone stock, and I hand-calculate my mpgs every fillup. If I do a rolling average of the past several hand-calc'd mpgs, the LOM is within 2-5%.

From what I observe, unless my driving is always the same for many tanks of fuel, real life driving mixes appear to skew the LOM numbers low or high for a while depending on what I drove recently.

If you asked me, the LOM is just a freebie calculated measurement for entertainment purposes...just like that "realtime" spectrum analyzer display on the Sync/Nav unit.