On my 2003 f250 super cab short bed I got around 18mpg hwy and about 15mpg city. On my new 2006 f250 crew cab long bed I'm getting about 9mpg on both city and hwy. I know my FICM is bad (just waiting on the deductible money to get it replaced... Should be next week) but would that result in such a huge mileage decrease, or could there be something else going on as well?

 

FYI, mileage figures are from my SGII.

 

Tire size, 2wd vs 4wd, axle gear ratio all factor in too.
lifted or not too. Just calc by hand. # miles/ # gallons to get mpg.
Be sure to verify (gps) speed and distance since rhey are possibly effected by tires and gear changes...

 

I was getting 18+ in my 06, it's starting to dip a touch with the cold weather, last tank was 17, the one before was 17.5 mpg. 70/30 highway to street miles.

Josh

 

Both trucks were 4x4 and both have the stock 17" wheels. Don't know what the axle ratio of the other truck was or what this one is, but I had thought they were all the same among SRW trucks? Neither truck is lifted at all. obviously this one has more weight, but not that much... SGII mileage was verified with the last truck by simple math... Haven't had enough fill ups with this one yet to get a good simple math average.

 

I calculate my fuel mileage useing the gps for mileage, it is about 15 miles more than what my truck reads.

 

Also discovered that my right rear tire probably has a slow leak... it was low when I test drove it at the dealer, and they put all the tires to 65. Right rear was back down to 20 yesterday! Put all four tires at 75 (rated for 80) and I got about 15 on the highway today, which is acceptable. Hopefully a fixed FICM will bring that up a bit more.

What would cause a leak that slow (been over a week and about 600 miles since I bought it)?

 

No nails or screws?

Might the valvestem. Squirt some soap on it and see if it bubbles.

Josh

 

Have ed @ ficmrepair.com add a atlas 40 tune to gain 1-2 mpg, then roll back the pcm. https://www.ford-trucks.com/forums/1...0-flashes.html I have done both and average 15 mpg combo driving, just got 18 mpg on a freeway trip non towing with my 8200 lb excursion!

 

Glad to hear you hit 15 hwy!
When I got my truck 2.5 years ago I figured on my 15 miles country road & top gear slow 50 mph highway commute I should be able to squeak out 20mpg.....fat chance.
If I have the patience and anticipate stop lights & really, really am a big soft foot suck.....I can get 18mpg; mostly average 16--argh!!!
From what I've seen on here 15-17mpg mixed driving will be your average; if you have a lead foot 12.

I had my FICM replaced on my 05 & all the flash updates done & gained a 1/2 mpg -haha -$1,400 later.

One thing that does makes difference is max out your air pressure in your tires-had my tires rotated & they upped the pressure to tire max of 70psi & I gained a full 1 mpg. Also if you don't need a true 'lug' tread go for grooved hwy stlye next time for new tires. Another 1-2 mpg or so if you are on the highway much. Wish I new that before I spent $2,200 on my lugged babies.
My father in-law drives a C*mm^s & easily gets 4MPG better than me; we each pulled our 10,000 trailers the same route & speed this summer-1,000 miles. I got 11 mpg to his 16. That's 45% better & I'm paying over $6 gallon for diesel up here in B.C.
I know don't mentioned the C word on here or be banned for life.......I really love Fords just want a couple mpgs better is all.
Good luck & I almost forgot-check your brakes are fulling releasing.
My rear brakes callipers where so badly corroded that they started dragging-talk about dropping mpg's!!!

 

Over the last 35,000 miles with all driving combined I averaged 14.5 mpg. Its not bad for a rig the weights 7,800 lbs empty. That includes about 15% of the time towing.

Thad

 

Thanks for the numbers, guys! In light of all your posts, really makes me wonder how I saw 18-20 in my old truck!

Unfortunately my next tires will be heavily lugged since I have about 330" of snow to deal with each year and my job includes towing people who don't know how to drive out of ditches. Haha... should be fun!

Maybe I'll invest in a second set of wheels at some point and keep highway tires for summer and lugged tires for winter.

 

Replacing your ficm is Not the same as having it rebuilt with a tune! I use cetane booster all the time, buy my diesel at shell stations if possible. I'm using as larger turbo with heavy tuning and am very happy with my mpg/power level! There is a 1-2 mpg winter fuel loss.

 

The newer PCM/FICM flashes are atrocious for MPG compared to the Buzz Flash and the previous Flash version.

I could hit 18-19 steady highway in my old 2005 F250 and it had a service body on it and weighed at least 9,900 pounds at all times.

Pulling a 7,000 trailer I averaged 12-14 highway with that truck. It also had the infamous Buzz Flash.

The newest Flash Version 9 might be the shiznit for induction heating and cold start, but I'll keep my annoying Buzz flash and 18+ average MPG any day.

Josh

 

I have the newest flash also and mpg do suck, is there a way to get an older flash? I live in florida and rarely see cold weather. I just ordered an atlas 40 ficm and will be throwing it in when it gets here but would like the peace of mind with an older pcm flash as well. Thanks and sorry for the