I just traded in my 04 Lariat for a 13 King Ranch. So far I love this truck, but my mileage sucks. My supercharged 5.4L was getting around 12-13 mpg on the highway. My F250 work truck with the 6.2 gets 13.6 mpg. This truck new truck has slightly larger than stock tires and an ecoboost engine. I wouldn't expect it to get nearly what it did from the factory, but I just did 500 miles highway and got 12.9 mpg... I've noticed the exhaust (which is aftermarket) has smoked my aux backup light and had some black buildup on the rear bumper, so thinking its running a bit rich? I bought it used, so I don't know if it has a stock tune or not. Plan on taking it to the dealer sometime this week to get it checked out, but wondering if anyone here knew what may cause it.

And here's a couple photos of it just because I'm so proud. haha

 

What size tires? If its not programmed then the speedometer is off therefore your MPG shows lower than what it should be. Black Soot is completely normal since its Direct Injection. What speed were you running on the trip?

 

The tires look larger than stock. If that is the case than you are getting more MPGs than what the readings on the dash are showing. It would have to have an aftermarket tune to recalibrate the speedometer and it probably doesn't. However, my truck gets better MPGs with a tune than it did stock.
Sooty tailpipes are normal for direct injection engines.

 

And also remember you have a Heavy Grill Guard, Toolbox, 4x4 etc..

 

Tires are 285/65R20 BFG AT. Pretty much the same size as what is on my work truck, but the work truck also has more toolboxes that are fuller, a bigger engine, and more weight (4x4, crew can, long bed). I haven't done the calculation by hand yet, but based on how many gallons I had to fill up for a trip I've driven before, I wouldn't be looking at much more than what the truck is currently calculating.

I was doing around 70 for most of the trip. 65 through some parts and 75 through others.

 

Traded my 08 5.4 in for a 13, but do not see the range of fuel economy they say. Just another disappointment along with the poor ac.

 

i went from a 265/60/18 to a 275/65/18 and when running the truck stock the speedometer was 4mph off and was showing 16.2 mpg (which is low for my truck) I was finally able to put my tune back on with a corrected speedometer and my mileage is back up to 18 to 18.5 cruising around town, But im also 2wd, 18" wheels and no accesories with extra weight.

Also with the Eb as you should know, the harder you push the pedal the more boost you get which mean lower fuel mileage. I've averaged 13 mpg pulling 6400 pounds to 22.1 mpg with cruise set on 68 for 230 miles. Average over 34,500 miles is at 18.0mpg Hope you get it figured out!

 

So it sounds like I need to find out if it has a tune and if not, get one. Who are some of the higher recommended tuners for the ecoboost F150s? I still have my PHP Gryphon and SCT Tuner from my 04 F150, so I'm assuming I would just have a mail order tune loaded to one of those and I'd be good to go.

 

DI engines produce black soot and you need to adjust the speedo for your bigger tires. You don't need a tune for your truck, just get a tool to change your speedo, or have a dealer do it for $100-150. In fact, I'd recommend against tuning it because that would completely void your entire powertrain warranty.

But I loved your old truck! Damn. I probably would've bought your bumper from you too lol. That would've been annoying for you though cause of the whole mounts being welded to the frame issue.

 

Which means that their diameter is 5.3% more than stock (275/55x20). Which means that your speedometer, MPG, MPH, etc. is also off by that percentage.

MEANING: When the speedometer indicates 60MPH the actual speed is 63MPH. *At 75MPH you're doing 79MPH.
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I really doubt it has a tune, but ya never know. As far as Tuners i'd Totally recommend 5 star and MPT.. For the price it will cost you to get the ford dealership to recalibrate your speedo you can get a couple custom tune's. Looks like you like performance with having a super charger on your previous truck therefore you will love the eb with a tune (i know i do)..

As far as Ford voiding your powertrain just cause you have a tune is not true. Be smart about it and you will likely never have a problem with the dealership.

 

Coy, it voids your warranty. Maybe your dealership said it doesn't and they'll stand by you, but trucks come into us tuned and we have to ask Ford, Chevy, whoever about it, and it voids the warranty. Dealers can tell immediately now if you've tuned your truck.

That's why Stage3 and 5 Star are offering powertrain warranties.

 

Yeah, it wasn't a super easy decision to let it go. It did cross my mind to yank that bumper off since I had only had it on there for a year, but I would not have been able to do that in just a day. That design made it pretty difficult to install and impossible to remove.

Well, that would explain why I was passing so many people on the highway...

Sounds good. I think I'll get the dealer to check it out just in case there is anything. But sounds like a tune is the way to go.

 

Well hell if i walked in my dealership and said Hey, guess what Im Tuned! Im sure they would void the warranty

All i am saying and its been proven numerous times, be smart about it and there wont be any problems. When you are going to the dealership put it back on stock, drive it for a 150 to 200 miles so everything is back to normal and not mention the tuner. If going with MPT or 5 star they have a damn good track record therefore chances are your not going to have to worry about failures due to the tunes.

My dealership is one of the rudest, non helpful dealers i have been to and havent yet had a problem cause i was "tuned"

 

That's not been "my" experience with it, but that's interesting. And you can't drive it for 200 miles if it breaks down haha.