I have been driving my F250 6.7 around town here for about 1 yr, and it has always maintained a rock solid 16.3 mpg average. Now while nothing has changed in my driving she only can give me 15.4. Somehow I have lost almost 1mpg and I can't figure out why. I don't believe that we get a winter blended fuel down here in FLA, and I always fuel up, at the same place. There is just about 8k mi on the truck so I doubt if the air cleaner is that dirty, and I dont let it idle any more then usual. It's less then 1mpg, but it's driving me crazy. I expected the milage to improve,not go the other way. any comments would be greatly appreciated.

 

You know, it could be the air filter. I recently changed mine and to my surprise found out that it is less than $15 for a new one. (my '08 6.4 was like $75)

It would be inexpensive for you to give it a try and eliminate that possibility.

You could also run some Motorcraft fuel treatment/injector cleaner but it will mess up your average until you burn it, you may get a false high average.

Tire pressures, wear patterns, rotation? Alignment?

The southerly winds have returned for the spring and the remaining cold fronts are coming in with more anger, maybe your prevailing winds have been stronger?

 

same thing got it october and been average 16.5. had the free update done in december,2 weeks later i am at 13.5 to 14.2

 

Nipperdog, have you done an oil change yet? I remember that the factory oil has some additives in it, maybe it's time for fresh stuff?

Do you ever run it for long periods of time? Might need a good 4 hour cruise on the interstate?

I have almost 37K on mine but I don't track MPG cause I'm towing all the time so I wish I could help more. I'm just going through everything I can think of.

My biggest MPG helpers and killers are mainly wind. I can get 14.5 one day and 11 the next. My monthly averages are always in the 12's. Last month was about 6000 miles, 400 some odd gallons of fuel, and I think it was 12.2 for the average.

 

DONE AT 3200 MILES WITH O.E. PARTS

 

MY FIRST CONCERN WAS THE VIBRATION IN THE DRIVETRAIN BETWEEN 40-45,WHICH STILL ISN'T FIXED. NOW WITH DIESEL @ 3.65 GL. STARTING TO WORRY ABOUT THAT AS WELL BEFORE I START TOWING MY CAMPER THIS SUMMER.

 

GEN MANAGER OF LOCAL AUTO PARTS! SO I STAY ON TOP OF IT. FORD IS BAFFLED ON THE VIBRATION, BEEN ROTATED, BALANCED, ALIGNED AND REPLACED. FORDS GOING TO TRY A 1300. DOLLAR DRIVESHAFT NEXT.

 

Just an FYI...typing in all caps means you're yelling.
Good luck with the vibration. Someone else here (Thom12) had it and ended up in arbitration with Ford and lost.

 

16 MPG around town is amazing. I hardly get that in the summer.
I'm running 13.0 currently (empty) with all local driving the past 400-500 miles or so (have not gone anywhere fun, too much working).
What I call local driving is some highway, county roads and city in my daily driving.

Now out on the open road, that's a different story.
I see mid 18's on the interstate moving at 75 MPH or even higher MPG if I slow down.
My truck just doesn't care for the city driving.
Which is fine because I don't either!
I would rather drive down the country roads with trees and fields.

 

I see guys post on here all the time about 16 in the city, i have only had my truck for two weeks now, but never get 16, i average about 13 to 14 hand calc and the gadge that tells you how many gallon you used is usaully alittle off too, it usually takes more to fill it then it says, I will say that on the highway, i set my crusie control to 68 and i got about 18.3 miles mpg which is pretty good, i have found my self trying to ease off the gas and start off easier to see if i can make a difference in fuel in the city, no difference that i can speak off much, would love to see 16 or even 15 in the city once, lol, my over all average is 13.3 from day one, and i only have 360 miles on it, i did read a post on here about running your truck hot and hard to open it up, i will wait awhile before i do that, its not broke in yet, and i cant wait to see if winter fuel makes a difference too, so come on summer...lol

 

He is also replying to the wrong post. He has another thread on this issue, somehow ended up replying on this one.

 

It's currently on its 2nd oil change. I'm going to install a new air filter tomorrow just to see if that is the cause, but I can't recall driving through any extremely dusty conditions since I've owned the truck. Mostly city driven with a few 100mi highway runs.

 

Yeah, I know what you mean. I hate changing that filter right before pollen season too, but mine was visually very bad and for what I think was about $10 I said go ahead.

I remember from my '08 that the air filter restriction gauge really needs an extreme situation to trip to a bad filter. And, you don't have many miles but a year is a year. With the CFM that runs through these things it certainly could be a factor. I'd still like to know the CFM rating on the system.

 

Yep that Donaldson air filter in the 08 was a real monster. I kind of expected to see the same setup in the 11 but was surprized to see the puny filter that they are using now. It dosen't seem adequate for the size of the motor, but I'm sure that Ford has done the math. I did about 30k in my 08 before the filter needed a change.

 

I try to clean the MAF sensor about once a year, but it should probably be done more frequently if someone travels in dirtier environments. Someone who does this must remember to use only MAF sensor cleaner and not any other kind of electronics cleaner because it will mess up your MAF otherwise.I've read stories on the M3 forums of guys who've tried other products and had to buy new sensors because they wanted to try some product meant for other applications, so don't trust any product meant for a different applications. A person doesn't have to use much, just thoroughly soak the wire/s and screen if applicable on the inside of the intake tube, let the residual dirty solution run from the part and let it air dry for a good 15 minutes before trying to start the vehicle.

YouTube - CRC Mass Air Flow Sensor Cleaner There are a couple of you tube videos that demonstrate its use, but this one is the best I could find. I'm not invested in this product, other than it's one of the products I use regularly.

I haven't tried to clean my MAF sensor yet on my truck, I've done it many times on my M3s and Yukon, but it's pretty easy to figure out how to access the MAF sensor and clean it in any vehicle. I recommend removing the sensor and spraying it while it is not still connected to the vehicle.

This is a bit more important when oil soaked air filters are used as oil may transfer to the MAF and cause excellerated degradation.

You may find that the vehicle is a bit more responsive after a cleaning.