I am consistently getting 13 (12.8-13.8) mpg in my truck. I have tried being easy on the throttle, drove 200 miles from here to sacramento averaging 55mph and I got 16.2 mpg. I average 80 percent highway mileage. I live 20 miles from town and typically drive around to the grocery store and do a few odd jobs, about 5 miles of driving in town and turn around and come home...average 13 mpg... This seems odd since half of that 20 mile commute is up a 50 mph safety corridor...and I go 50, in the 65 zone...I go 65...I tried going 60 mph every day instead of 65...never noticed a difference in gas mileage. The truck seems to idle slightly rough to me, but it could just be its a 5.4 with 90k miles...who knows. No CEL's... But it has new spark plugs...tried changing the oil, fuel filter, transmission fluid... Tried being easy on the gas...doesnt seem to matter much. I average 9 mpg in my 92 f250 with a 5.8...pulling a 2000 lb 10 foot trailer daily, 2 people, and a big 500 lbs dumpbed filled with 500lbs of crap... on the same type of commute, me flooring the **** out of it everywhere, and with a TON of start stop, off and on 50/50 hwy city driving... Just doesn't seem right to me. I have been reading around, and everyone seems to say they average 14-16 mpg...Considering my driving is mainly highway at low speed not towing or hauling ANYTHING....why is my gas mileage so sucky?

 

How many miles are on your truck?

What's your gear ratio?

Have you changed your air filter recently?

Are you running larger and/or wider tires?

Are you running a lift kit?

Have you replaced the plugs and cops since new?

What tire pressure are you inflated to?

Do you carry a bunch of extra weight (i.e. tools, toolboxes, things in the bed)?

These are all factors that could individually affect your mileage. If you find that you're answering YES to a bunch of these, then you're just compounding the affect.

Let us know what you've got with more detail. I'm sure we can lend some advice.

Just FYI, on 11 fill ups, some 2200 miles, I'm averaging 14.3mpg in my 06 SCrew FX4 with 3.73s. I'm 70% city though. Best take was almost 17, worst take was in the low 12s.

 

I tried to rep you but the rep gods said no but awesome post!

 

Thanks!

 

you bought a truck, not a prius

 

rwdfan - Pretty much the same boat here. I've got a 2004 F150, 4x4, 5.4 ltr. 134,000 miles. Purchased it brand new and it is extremely well maintained. My bed mounted tool box probably has about 150-200 lbs of stuff. Routinely get 15-16 hwy, 13-14 city. Used to get 1-2 mpg better before I regeared it (went from 3.55 to 4.10). Plus, seems to have dropped slightly after it hit 100K.

Anyway, just posted to let you know that your numbers don't seem too out of line for this truck!

 

I was getting 10 mpg city when I got my F-150 22 months ago. Now I get 11.5 city and 16 highway at 65 to 85 mph at mixed conditions of mountian passes, flat desert as well as against or with the wind. My truck weighs in at 5,500 lbs with my tools but no passengers. I frequently weigh my truck at the steel recyclers.

I have 3.55:1 gears with 275/65/17 all terrains. It is two wheel drive. It has the 9.75" ford rear-end and the 4R-75E transmission. The truck is not lifted. It is a 5.4L 3V stock with a custom fabricated 3" Y-pipe.

I want to re-gear. Any Idea what kind of hp these motors get with 3" single exaust?

 

When I had my 05 FX4, I averaged 13 stop and go, 16-17 highway travel around 70 mph. 5.4 with 373's and 18' wheels. Towing my 28' travel trailer was about 9 mpg. Pretty much average for these trucks, depending on options, weight, and driving habits.

 

Just curious as to the precentage of ethanol that you are running in your area. That drops the MPG's by 10-15% on mine with 10% ethanol. My mileage is down but I carry a lot of extra tools and junk in it.

 

10% here too everywhere in the Richmond area. Winter blend is even worse. Can't wait for that to start hitting the pumps.

 

How many miles are on your truck? 90k

What's your gear ratio? Not sure, whatever comes stock with a 04' 5.4 4x4 supercrew lariat with stock 18' wheels

Have you changed your air filter recently? Yes

Are you running larger and/or wider tires? No, truck has stock size all terrain tires.

Are you running a lift kit? No

Have you replaced the plugs and cops since new? Yes, BRAND new plugs...not sure on the cops, but I know they were tested at the same time as the plugs were replaced at dealer 10k miles ago and were within spec

What tire pressure are you inflated to? 42 lbs pretty sure, whatever it says on my gas filler door. I have an air compressor in my garage and check both of my trucks tires weekly.

Do you carry a bunch of extra weight (i.e. tools, toolboxes, things in the bed)? I have a small toolbox that is meant for a ranger that I put in sometimes that is usually empty. I use it to carry a few small gallons of pesticides for my gardening business. That is it all99% of the time.

I know I bought a truck. But I spend about 700 dollars in gasoline a month between my two trucks. Just looking to shave a few bucks off of that.

I am not sure of the ethanol blend here. I buy my gas at renner petroleum locally. Its CA blend gasoline. Also, on the comment of gas mileage of 14.3 mpg. I would love to get that, you also have to realize you are still averaging 1-1.5 mpg than I do with an FX4, more aggressive tires and I'm sure a shorter gear ratio than whatever mine is. I drive at LEAST 70% highway. Also ,the comment of 13-14 mpg in the city is what I get on mostly highway.

I have thought still about it being weak COPS. I know the dealer said they checked them, but since they were footing the bill, there is a good chance they need replacing.

 

If you are replacing the COPs you may want to consider the Accel #140033-8 set from Summit or Jegs. They cost around $280 for the set.

 

How would I go about testing my COP's? I really dont want to dough out almost 300 bucks that I could be using on something else to help my gas mileage.

 

I purchased a ScanguageII from Autozone,and installed it in my 07 XL.
While it wont directly effect your mileage,it WILL change your driving habits(it did for me anyway).This plugs into the OBDII port,and will give you a real time mileage readout,and well as trip average,and a whole bunch of other engine parameters.Tach,Temp,etc
Admittedly,I have the V-6,and mileage wasnt too bad to begin with,but having the real time fuel consumption figures at a glance will open ones eyes.Adjust the foot accordingly,and you will get the best economy possible.
I do NOT work for Autozone,and rarely purchase from them,but this works....

 

n5926g is correct; the Scangauge will help you monitor your 'go foot', but a vacuum gauge will provide the best indication of instantaneous MPG; Less vacuum means more fuel.

Here's a great link: How to Use and Interpret a Vacuum Gauge

And here's 132 posts re: MPG mods http://www.f150online.com/forums/200...y-mileage.html