05 f-250 cc lariat fx4 srw fully stock and about 2700 miles...

I didn't buy the truck for fuel economy, but wasn't expecting this either... seems like the past three fillups have been producing less and less mpg. The best I have ever done was on a 300 mile trip to Wichita Falls from Austin. Not terribly hilly and set the cruise on about 70 or so.. averaged about 15.2 mpg. since then, the mpg have dropped after every fillup. Last time I filled up, the computer said 14.6 mpg, and after filling to the top of the neck (like I do everytime) it was about 14.7. Now the mpg meter is saying 13.2 and after 65 miles, I am already hitting the actual "full" mark which I usually don't hit until around 100 miles or so....

can anyone tell me if I have a problem or am I just crazy? Well, I can answer that one! I am not expecting honda like numbers, just 7.3 numbers will do. Heck, how about 15 mpg again!

Just had to vent a little... Ford talks about a new 6.0 which is suppose to get better fuel effeciency than the old 7.3, and I know some are getting it, why the heck am I not... you would think in a day of mass production and everything having to meet the same specs that all would be within a few tenths of a mile of eachother...

if anyone has any suggestions, please feel free to chime in.. Thanks

oh, most of the driving is highway... I live out of town a little and my office is on the outskirts of town, so very few lights and no stop and go traffic.

 

Welcome to the forum, afrantom!

With a LOT more horsepower, and if you USE that hp, not sure how we can get better mpg

What kind of rear end ratio do you have ?
what size tires? what air pressure? do u accelerate hard...

U allude to it, but not sure if you are using JUST the overhead lie-o-meter to report your mpg....
if you are, have u reset it between fillups by holding both buttons in until it resets?

keeping the rpms below 2K seems to be the real economy setting...

ON one trip back from Memphis to Dallas, was not in my usual hurry, in fact, we were listening to a great book on tape we wanted to finish, so I slowed WAY down... never went over 65 I think, and the overhead reported 22. something... actual hand calcs showed 21.5 !!!
I was stunned that a 8k+ lb beast could get that great mpg with all I was carrying !
(course I do have a few mods that may have helped like the predator and turbo back exhaust - and aired the tires up after I got my adjustable rancho shocks)

but please know that I didn't buy this truck for mpg....

 

Sorry to hear the mpg isn't any better- In addition to JD's questions, have you done your first oil change? If not, do it.

Good Luck and please do report back (good or bad)

 

sorry, don't tow anything, 3.73 gear ratio, tires are stock bfg's on 17 inch rims and the tire pressure is 70 psi I think... don't accelerate overly hard and I do reset the trip computer and the mpg meter everytime I refuel and then hand calculate and compare to the computer... looks like I am a little over half way to your 22!!!

 

Seems like with the wind and colder temps here in dfw area, MPGs have gone down 2-3 mpgs since summer. I wonder if we get any winter blend fuels around here? Im getting around 14.5- 15 hand calc. Was getting 16.5-18 in the summer. About the same thing happened last winter. Im not worried in the least.

 

Are you resetting the computer each time you fill up by pressing the two buttons at the same time. When you do this, the display should go to 0.0 if you are sitting still at the fueling station.

I suspect what you are seeing is the cumulative mileage for city and highway and all that combined. The city driving has a much heavier bias on the average than the highway driving, i.e., it doesn't take many miles at at 12 MPG to pull down the overall average for the rest of a tank driven on the highway at 19 MPG.

You can reset the computer as often as you like. I do it sometimes to get a feel for what the "instantaneous" MPG is for a given condition like cruise after I've gotten on the highway or pulling a steep hill, etc.

I record the fuel used and miles for each tank and put them in a spread sheet. I always top of the tank the same way - to the filler neck.

 

yes, I always reset everything.. I too have done the reset while driving, and within a few minutes, it is right back to the 13. to 14. something.

 

just rolled 3500 mi on 05 F-250 and average 18 hiway, and between 15-16 city. very satisfied. hiway speed between 70-75

 

I wish I could average 15 MPG. I love everything about my truck but that. I am getting 11-13MPG. I have been running my Super Chip in high performance mode so I guess I will try the economy mode to see if that helps. I know I propably loose a couple of MPG with the 35" tires . I envy you guys getting the 16, 17, 18 plus MPG. Would it help to get an AFE or Airaid filter?

 

Hi Pitchinfool

Welcome to the 6.0 L forum and to FTE. Please take a moment to review the Welcome sticky post at the top of the forum page. There are links to great threads and other info in there.

Has your odo been recalibrated for the larger tire? If not, you'll actually be traveling further than what shows up on the odo and your mileage may be better than you think. Just a thought.

 

Daryl, I had the odom recalibrated 2 times now but it is still off about 4 mph. The last time it was recalibrate at 590 revolutions per turn ao I called Toyo again. This time they told me it is 596 per turn. Plan on having it recalibrated again next trip to dealer.

 

Being in Austin, your winter blend is probably coming in about the same time as us here in the DFW area....
but you ARE in the "hill" country so that has a bit of an impact....

but like you, I suspect yours is not running at peak yet...
there was a new flash for the trucks computers that just came out this month, so maybe give your svc people a call and just talk to them to see what they say....
if they are not responsive, there are other dealers in Austin and bet they would love your business !
Good luck and keep us posted...

I hope your truck gives u the great service MINE has

 

OK so you have a new truck and your getting below average mileage. Don't expect the greatest numbers while the engine is new. Diesels have a long break in period. I was averaging 13 to 15 mpg the first 6,000 miles or so. Part of that was the honeymoon period where I was loving the throttle maybe a little too much. Lot's more power then my old 93 F-150 my F-350 replaced. You should see some improvement after 8,000 to 10,000 on the o-meter. In the mean time, keep a close eye on the oil level. If you have an injector o-ring leaking a little, you oil level will rise slowly and this will also have an effect of your mileage. Also, what kind of fuel are you using? You'll see a drop in mileage if your pumping diesel #1 into your tank as opposed to diesel #2.

 

I also had low mpg when i bought my 04 F-350 SRW 4x4. I was seeing around 14 or so average. I know how 28,000 after 14 months and i am seeing around 19 and better at times. I have the short bed and usually pump in around 30gallons so i am satisfied with that kinda range. I agree with the others in saying just be patient and remember it takes alot longer to break in then a gasser. Also on a side note about the tires. My truck being a 350 SRW i recieved the pirelli load range E tires and they are off with my factory set speedo. The truck is actuly going about 3mph slower then what the OD reads. I know it puts more miles on the truck then are actuly there and that isnt good but i cant take it in and loose a day of work for that. I am getting GoodYear MTR 315 75R16's (35in) this weekend so that will fix it :-) .Try using a gps to get the accurate speed. That makes a difference. Good Luck

Ryan

 

all, thanks for the input and advice... I just in the last few minutes got an oil change, so hopefully that will help. I am probably just over reacting, but I will kepp you posted on the results in the next few weeks... Thanks