Welcome to FTE! Sorry for your issues. She needs to go back and the dealer needs to have a good look. But, if she's not showing a CEL, she may not be throwing any codes.

 

Just remember you have to drive for economy and that takes a bit of restraint in the beginning, "cause it's just too much fun". Watch the green real time mpg gauge and you will quickly learn what it takes to get the MPG's out of it.

 

I'm not sure what driving for economy has to do with the highway miles. This weekend I put 260 miles on it across the turnpike where I was able to set the cruise control and never touch it again until I got off. I reset the average meter after I was already on and accelerated and looked at it before I had to decelerate to get off at the exit. I only had to turn the cruise off 3 times for traffic and only varied by 5 mph when I did. I got 15.6 doing 73 mph on flat ground with a tail wind.

Turning around and coming back into the headwind later in the day I decided to say screw it and came back at an average of 78 mph and ended up with the highest mpg I have seen in a long time. I got 16.3 on the way back. (Maybe it isn't flat after all)

Now my actual mpg was much lower than those figures because I was already accelerated and no stopping and starting. I only had about 15 miles of non-highway driving on each end of the trip and a little warm up time before we headed for home, but I ended up with about 15.3 overall. I just wish I could have gotten the bigger fuel tank...

I'm up to just shy of 2000 miles now and my lifetime average has gone down to 14.8. I'm not looking forward to walking into the Ford dealer and having them tell me that it is normal for mileage to decrease in the winter colder weather.

 

Look I just hit 2600 miles on mine and let me tell you friends, I spent the better part of 10 hours ( 5 hours each way, on my trip from Metro Detroit to Chicago ) and never hit anything over 18 MPG on my truck. The ONLY time I hit 18 was approaching downtown Chicago in the horrible traffice going between 45 and 55 MPH.

Again, I tried everything, only way you'll ever come close to the sticker number is if you drive NO faster than 55 MPH and if you really want to fool yourself reset the lie-o-meter 4 or 5 times during your trip

My truck has the 3:31 gear, if you drive the current speed limit of 70 MPH you'll never hit the advertised MPG. Again, stop fooling yourself

 

I'm achieving 23+ routinely at 70 MPH. Cruise control is no friend to gas mileage. The computer will run the hell out of the truck to maintain the desired speed.

 

You are getting 23+ at 70 mph in a 4x4? I guess I should be disappointed then. I had been hoping for 18ish. I'm only dissapointed because I can barely make 15-16.

I had someone following me today and they said my exhaust really smelled. They asked if I was really running rich?

 

Don't get me wrong. If I gas up and hit the highway immediately then I'm hitting 23+ like I did tonight and so many times in the past. But, my average daily driving is typically around 18 mixed, city and highway.

 

That is where my frustration comes from. I live right next to the interstate and my work is just off the interstate, so almost exclusively interstate round trip of 250 miles. And that is where I average only 15-16. That is why my life average over the 2000 miles is 14.9 because there is hardly any city driving. Otherwise I bet it would be 12-13 range. I did a stint where I stayed home and ran the kids around and that tank was around 10 mpg for the week... Ouch.

 

23 MPG no way...serious....I never use the cruise control, as soon as I see the MPG decline, I left off the gas, I'm that **** about getting max mileage.

Ford was foolin' all of us when they printed that on the sticker. Guess my biggest deal with the hole thing is I've had nothing but Superduties since 96', this is the first light duty truck I've owned. Ford never prints the MPG on the big trucks, so I was really excited to see the 18-21/22 on my sticker. I was really hoping that's what it would get.....oh well

 

Unfortunately these window stickers apply to the lightest trucks with the tallest gears. At 65 mph, I'm taching about 1500 rpm's and reaching 23+ on flat land. I have no reason to lie.

 

I posted in a couple of other places but you might try turning off the trailer sway control. I found a nice jump in highway mileage with it turned off. It was trying to control sway all the time and dragging the rear brakes. I still see huge swings for no reason from day to day but it does seem to help some.
Worth a try.
And it resets to on every time you crank up so you have to turn it off every time.

 

I have 6000 + on mine now and have always got 17 - 19 mixed city highway and 20 -23 strictly major highway. Last big trip was Fort Pierce, Fl to Pittsburgh, Pa 1170 miles lowest I got was I think 18.5 in the mountains of WV and 20 -23 the rest of the trip. I still get agitated when I get below 20. One day I filled up in Ft Pierce reset the meters and went to Stuart, Fl about 30 miles along the river at approx 40 mph the whole way, no stops or lights and very little traffic. When I pulled into Stuart I was getting 28 MPG and have a pic I made my wife take cause I will probably never see that again!

 

Keep in mind I live in Florida, flat, no cold starts or warm ups. My truck is 2wd and has 3.15 rears, supercab and 6.5 bed which is not loaded down with anything. You should be getting much better, especially if you are really **** about economy. I would have to guess you got something wrong. Of course the numbers posted by Ford I think are at 65 mph not 70 -80 mph and I'm sure under much different conditions.

 

Here is the pic it was about 3 miles out from Stuart and It hit 28 just before we pulled in. As you can see the instant guage is maxed out at 30 mpg, 1000 rpm and 40 mph. Also the truck had 511 miles on it then.

 

Here is some interesting reading, ya never know!

All I can tell you is that sway control defaults to on all the time. You have to turn it off every time you crank up. I actually felt the brakes release when I turned it off on the interstate. Mileage immediately went up.
I assume there are some kind of rate sensors in the rear of the truck that detect sway.
I know based on my experience that it was activated and I had no trailer connected. I would assume it is there for when you have a heavy load in the bed as well to help prevent rear sway.

As for the 02 Sensor, mine was fine. Not my problem w/ poor economy but could be on others.