Got a 2008 F-150 crew 150wb 5.4 ffv 3.73 limited slip.Getting 17-18mpg now truck has 2300miles on it.Bought a tonneau cover no help.Replaced air filter with k+n filter in stock box and removed the 2in intake tube and replaced wih 3in pvc in stock location no help.What next?Sick of driving like an old lady to save gas.Do programers or cat back exaust help at all?

 

17-18 MPG is pretty good.
Is that all Hwy?

All hwy I get 20 mpg driving like a old senile half blind lady.

Only mod I have is Dual Exhaust, and I don't think that made any MPG difference.
Sounds and looks good though.

From what I've seen, I'd say programers don't give more MPGs, but some claim a MPG or two.

Only thing I've seen that works for everyone every time is Electric Fans and underdrive pulleys.

 

if driving like a grandma is not something you're willing to do, get a beater gas saver car. Unfortunately, 90 yr old behind the wheel is the only way pretty much to get better MPGs out of these trucks.

 

17-18 is pretty good for a crew 5.4L, I dont know many that get any better than that. Thats all I can get out of my 4.2L reg cab driving to work on the highway driving 65 or less (well since moving to my new house thats 40mi hwy trip, 17.5 is the highest I've got so far).

 

Once you have a few more miles on the truck, the mpg may go up a little. But, as you've found, there's very little from a mod stand point that you can do that will really give you improvements. Ya, there are folks here who have found improvements from tuning, cat backs, cai's, etc. But unless they are monitoring/tracking mileage over a long period of time. The gains they may have seen might just be tank to tank variations.

But, you can do all the regularly suggested things like. Keep unnecessary weight out of the truck, run tires at proper or higher pressures, replace your tires with a lower rolling resistance highway tread type tire, drive with the windows closed and yes drive conservatively.

17-18 mpg is respectable for these trucks.

Good luck finding a means to improve your mileage that's not just another snake oil gimmic.

 

Just filled up today 420 miles took 23.2gals 18.1.Most of my driving is 45-55 range i live in a small town with 3 traffic lights so i never have to sit in traffic or anything.I did take one highway trip a month ago 70-75 mph didnt seem to get any better maybe with 3.73s thats as good as it gets.

 

dude just change your gear ratios chsnging from 3.73s to 3.55s will boost your mileage from 17-18 to at least 20mpg maybe up to 22-24 mpg
think about it

 

I don't think it will help your fuel mileage much if at all.

 

well changing your gear ratio to a lower number lowers your rpms at crusing speed and what happens when you lower your rpms LESS FUEL USED!!!and it might save you from driving like an old lady here i will simplify it for you
Higher gear ratio = lowered RPMS at crusing speed = less fuel used = less driving like an old grandma

 

The difference between 3.73 and 3.55 isnt that much, like a 5% reduction, no way your going to get 33% increase in fuel mileage. And this is going to help the most at hwy speeds. Around town having to stop and go it actually can make it worse since the the engine has to work harder to get the truck up to speed with lower # gears. And look at the cost of having the gears swapped, I doubt it would even pay for itself in mpg gains unless you drove it for a long time.

 

have you ever ridden a bicycle?

 

That's up there on one of the dumbest things I've ever heard list.

Yes a lower (pneumatically) gear ratio will lower hwy RPMs, but the small difference will not make a noticeable difference guaranteed.
A taller gear like 3.55 means there isn't as much gear ratio like 4.10 to get the truck moving which in turn uses more gas. SO the more gas it takes to get up to speed will not be over compensated by the 100 RPM drop of the gear change that would cost a easy $600 per axle.
So if you have a 4x4 with 3.73s and you re-gear to 3.55 it is going to cost you $1,200 easily, while making the truck sluggish on acceleration, while barley lowering the hwy RPMs (once the truck is in overdrive the 0.22 difference in gear ratio will NOT be noticeable and will NOT help gas mileage).

 

beat me to it MBB

You might see significant MPG savings if you switched to a 3.23 gearset vs. a 3.73 gearset...but only if you drove 100% highway...even then, I think that would put the RPM out of the power band and you'd use more fuel to get back up there

The only way to save MPG is to:and for y'all for feel the need for the extreme, here are a few more

 

Have no desire to start a firestorm, but here is my take. The Auto manufactures spend a lot of money and time to extract the best all around performance out of these vehicles. Granted there are advantages to using tuners, but to expect them to be the magic pill for dramatic fuel savings is a pipedream. I worked at a GM Proving Ground in the 70's and fuel consumption was always a concern. Don't shoot the messenger!!

 

If you change your tires to highway radial , you might gain 1-2 mpg, you have to watch the pressures. Do not put a lift kit on it. The factory slant is for aerodynamics. Check the air filter frequently and possibly switch oil to Royal Purple synthetic. You might get a total of 1-2 extra mpgs per gallon, with this all done.
I have only 7000 on my truck, 5.4,3.73,4X4, scab and only get 14.5 mpg .