mileskl

My 2013 F150 4X4 Supercrew EcoBoost 3.5L v6 with 3.55 axle is getting about 14mpg in town (14.5 if I really baby it). I can get around 17 on the highway at 70mph. I've had the truck for about a year and it has 80K miles on it. Any suggestions for improving gas milage? My brother-in-law has the exact same truck, except 2WD, and he gets 20+ combined mpg.

Roughneck12

These trucks are really sensitive to extra weight, hills, wind, winter gas/summer gas, what kind of tires you are running etc.

Pickupman66

I have a 13 Screw FX2. 92k. I average 17.7 -18.5 in my daily drive. it is 45 minutes to and from work. Over a 5 mile long 5% grade up and 5 miles down. I run 65 up it and roll 70 down. 75 in the flats.

Old Machinist

Kicking an old thread to the top. Just did my first mileage check on a new to me 13 and it came in at 14.5. The computer reported 15.5 for the 365 mile trip. On the way home the computer went up to 17.

70% of my commute is 55 MPH highway and I use cruise control on every stretch of road I can. I am pretty disappointed with those results. My old 4.6 V8 would average 17 and could get north of 20 on the highway. Both trucks have the 3:55 diff.

Pickupman66

Wow. Way back machine. I'm up to 215k miles and still popping over the 17 mpg average. Commute has changed so now it's 20 mins rural roads and in town driving. I've seen over 18 a tank or two per the computer. Normally it's just me in the truck. I've had to get a new throttle body (Dorman stock replacement) and I broke the cold charge pipe feeding it so upgraded to the aluminum. That's really it. Super happy.

I also have a travel trailer that we tow within a days ride. Typically I'm seeing 8-10 mpg towing about 7k from this not exceeding 65mph. Mostly between 50 and 60. I added air lift bags to the rear and wow what a difference in ride control and comfort.

mass-hole

Then I guess you need to start poking around and see if anything i causing the issue. A 2013 is a 10-11 year old vehicle at this point and things wear out. 55 mph should put you up over 20 mpg assuming the truck is all stock and in good condition.

ColdWarVet607

Most likely the poor gas mileage is caused by crud build up on your intake valves. This is a known issue for the 1st gen (2010-2013) 3.5 Eco Boost and for any direct inject engine. As gas is injected directly into the cylinder, the gas never hits the back of the valves, the valve seats and intake port in the heads to "wash" away crud that acquires on them from combustion in the cylinder or oil and crud from the EGR system feeding back thru intake manifold. Port injected engines have the advantage of the gas mixed with air and traveling over the ports, seats and valves and helping to dissolve most the crud build up. In the 2nd gen engines Ford still had the direct inject but also put gas down the intake manifold as well to clean the valves. Run at least 2 bottles of Seafoam or similar product cleaner thru your throttle body, see how that works and use it regularly to keep your valves shinny new...well almost. Direct Injection or not engines that never hit high rev's such as just around town drives can suffer from this build up. High and I mean high rev'scan help knock off crud from the chatter. Chrysler recommended town driving only Soccer Moms go on the highway and rev it to hell to knock off valve crud on the Pacifica's. Theres other known issues for 1st gen 3,5's, the timing chain loosens so you are not firing at TDC or the right time although thats probably minor contributor. GDI has its advantages no doubt but nothing is perfect, it was implemented to provide better gas mileage due to our Federal Govt which doesn't care one bit how these political mandates cost the regular folk thousands and thousands in repairs or just plain old short life of todays "fuel efficient modern cars". Hers an article on the 3.5 and its know issues, which of course all engines have "known issues". https://www.motorreviewer.com/engine.php?engine_id=144

Barry_Vee

The solution to your fuel mileage concern at 80k is not going to be carbon buildup on valves. This forum has dearth of actual reports pertaining to the issue on even high mileage engines.

Have the spark plugs been changed? IME 60k is about maximum for recommended plugs. Many owners change plugs even earlier. Use silicone grease and consider changing plug boots.

Try cleaning the turbo boost sensor located in the charge pipe just ahead of the throttle body, and the manifold air pressure sensor located on top the manifold towards the rear. Use a MAP spray cleaner and don’t touch the element.

Change the air filter.

Less likely front calipers are not fully releasing. There is a clamp holding the rubber hose that can pinch off the line as it rusts. Solution is to pry it open a bit or replace.

Has the truck has been “leveled” or raised? Does it have aggressive, wide or LT tires installed? These modifications cut gas mileage.

By description your mileage is about 2mpg less than mine in a similar truck with KO2 LT tires, (when driven like an old man).

2011 XLT Screw 4x4 3.5L 3:55LS 194k miles

Oops, just realized how old this thread is!