Low MPG in 2011 super crew XLT

[Big Slick]

Well I have had my truck for just under a week and my mpg is not where I think it should be. I reset my mpg twice now and I am still getting around 12.8-13 mpg. My dad has the same exact truck minus the running boards and rear camera and his truck is getting closer to 18 mpg. My dad says that after oil changes that he gets better gas mileage, but the oil was changed at the dealership when I got the truck.

Why is mine so low and his is so high? I haven't gotten on it only 2-3 times for a little bit, but for the most part I coast a lot when driving. In all honesty I would say I drive like an old lady in this truck. I would think my mpg would be higher than 13. Even online I am seeing people posting 16-18mpg.

What do you think is going on?

[Jersey_Joe]

Tire pressure? Tire size? Air filter? Fuel filter? Run some gas treatment through it and put 89 octane or better. Try that first

[Big Slick]

Will do thanks

[RhinoZ24]

The basics, like Joe said. Properly inflate the tires, check the air filter. I don't know how many miles are on the truck but the fuel filter should be replaced every 30,000 miles. Run some fuel system cleaner through it, I recommend either Lucas or Gumout, both are only about $5. If you really want to clean your fuel system, valves, etc. get ZMax, its like $30 though. Also, you could have what happened to me when I first got my '05 about a year and a half ago. I was getting like 10 mpg at first, the air filter was brand new, but I found 4 or 5 leaves in the filter box. It was restricting a lot of airflow, went up a good 1-2mpg after that. I also had some leaves where the snorkel hooks into the fenderwall. Check for that. Clean your throttle body as it might need it too.

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What do you drive mostly though, city or freeway? And your dad too?

[5.0Flareside]

Air filter, tuneup, quality of fuels..

And NUMBER ONE killer of fuel mileage.. Driving style.. What's he difference? He slow and steady? You racing from stop lights?

And tire size/inflation.


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[Big Slick]

He's a lot more highway and I'm mostly city so I think that clarifies everything.

I don't floor it between lights. I learned that from driving my mustang. I know how that kills your gas mileage.

[RhinoZ24]

Well the 5.0 was rated for 15 city mpg. Just do what we suggested and you should get your mileage back up there.

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Also calculate your MPG's yourself, the computer isn't always accurate. You might notice a difference if you calculate it yourself.

[RhinoZ24]

Any updates?

[BFEB]

Are there a lot of stop lights on your commute? Sitting at lights is the worst thing for mileage there is. Other than just idling constantly for no reason that is lol

[Big Slick]

2 lights that I rarely hit. Some stop signs too. It's a short commute.

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Hoping to do some investigating this weekend.

[BFEB]

Well for comparison mine is sitting in the low 14's with my 4mi daily trip to work. There is one stop sign and 6 lights on my route. I usually miss most of the lights tho.

[RhinoZ24]

2 lights that I rarely hit. Some stop signs too. It's a short commute.

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Hoping to do some investigating this weekend.

Alright, I'm sure you'll find something that's causing it.

[Jax]

Hey Big Slick, I am in the same boat with you! I have a 2010 FX4 w 3.73 gears and 5.4L FFV. Best i get is 11-14 mpg. I have been dealing with this since November (when i bought the truck) and have not found a solution yet. The reason i bought the truck is my dad has owned several through his company and would usually get 16-18 mpg. I have done a lot of the regular stuff (except fuel filter which is apparently a lifetime unit built into the tank?)

One thing which I have found but haven't checked yet is O2 sensor failing. Under normal complete failure it would throw a code, but I have heard they could wear, not work properly, but still operate within the acceptable range. (as far as the computer is concerned.) Might be worth a visit to the dealer to check it out but I haven't made it there yet. Apparently they can monitor the O2 sensors in real time while driving the truck. Just a thought.

[RhinoZ24]

Hey Big Slick, I am in the same boat with you! I have a 2010 FX4 w 3.73 gears and 5.4L FFV. Best i get is 11-14 mpg. I have been dealing with this since November (when i bought the truck) and have not found a solution yet. The reason i bought the truck is my dad has owned several through his company and would usually get 16-18 mpg. I have done a lot of the regular stuff (except fuel filter which is apparently a lifetime unit built into the tank?)

One thing which I have found but haven't checked yet is O2 sensor failing. Under normal complete failure it would throw a code, but I have heard they could wear, not work properly, but still operate within the acceptable range. (as far as the computer is concerned.) Might be worth a visit to the dealer to check it out but I haven't made it there yet. Apparently they can monitor the O2 sensors in real time while driving the truck. Just a thought.

The fuel filter is definitely not a lifetime thing, it will need to be replaced eventually. It should be every 30,000 or so miles like most vehicles. And the O2 sensor shouldn't be affecting mileage as far as I know.

[BFEB]

Hey Big Slick, I am in the same boat with you! I have a 2010 FX4 w 3.73 gears and 5.4L FFV. Best i get is 11-14 mpg. I have been dealing with this since November (when i bought the truck) and have not found a solution yet. The reason i bought the truck is my dad has owned several through his company and would usually get 16-18 mpg. I have done a lot of the regular stuff (except fuel filter which is apparently a lifetime unit built into the tank?)

One thing which I have found but haven't checked yet is O2 sensor failing. Under normal complete failure it would throw a code, but I have heard they could wear, not work properly, but still operate within the acceptable range. (as far as the computer is concerned.) Might be worth a visit to the dealer to check it out but I haven't made it there yet. Apparently they can monitor the O2 sensors in real time while driving the truck. Just a thought.

That sounds about right for a 5.4. That's just a lil better than my 08 with the 5.4 and 4 speed got.

[Jax]

One other small thing...my dad always had a soft tonneau cover on his trucks which mine did not have initially. I bought one in Feb and put it on (was my plan all along anyway) and it was good for a 1-2 mpg increase on the HWY in my truck. I was really low before (12-13 on hwy) now it's around 14-15. I never thought it would be that dramatic but it's what I'm seeing anyway....still low, but a bit of an improvement.

[Big Slick]

I have a tonneau cover too.

We did some researching this weekend and found that the air filter was more than likely the culprit. It was pretty nasty looking and there were a couple of small leaves in the air box and even some pine needles. We installed a CAI this weekend so I will see over the next week what my mpg does.

[BFEB]

I'm surprised the dealer didn't throw a new filter in it. I think that's part of my dealers check they do before selling pre-owned inventory.

[Big Slick]

There's a lot of stuff I was dissatisfied with from my dealership.

[RhinoZ24]

I have a tonneau cover too.

We did some researching this weekend and found that the air filter was more than likely the culprit. It was pretty nasty looking and there were a couple of small leaves in the air box and even some pine needles. We installed a CAI this weekend so I will see over the next week what my mpg does.

Told you lol, that was the same with mine. You'll notice a difference for sure. I gained a good 1-2mpg when I cleaned mine out.