Stock 4.6 needs mods for better Fuel Mileage
 

Hey all,What's the best route for mods for a 2003 4.6 for better fuel mileage? I am thinking about a intake, a catback and whatever else.With the catback, would a 3" single or a 2.5" dual exhaust catback? Should I look at a special muffler or get a complete setup from E-Bay. I thought about going to my local muffler shop and having the job done.With the intake, would a cheapy $40.00 E-Bay intake work or a K&N system?I am driving 80 miles round trip a day and I need to do whatever to save gas. A little extra power would be great too.Thanks,Mark

Others will say different, but the best advice I can give you is, keep your money in your pocket, keep the truck stock, and try to save up for an economy car if fuel mileage is important. If the truck is operating as designed and has had a tune up recently, youre just not going to come out by trying to squeeze a MPG or two out of it with add ons.

^^ I would agree. The general consensus seems to be that while a CAI and/or exhaust might make a bit of difference, you will almost certainly end up behind because those parts cost more than you will save on gas. When I had my 2002 with a 4.6 I added a CAI and it didn't make one bit of difference. The best advice I ever got on these forums for increasing mileage was regarding driving habits. A quick search will provide lots of advice on that.

I'm gonna have to agree with the rest!
Your wasting money on them mods and most of them for MPG.
Maybe try a tuner for a little more power and mileage. (LITTLE) lol

Yeah, the tuner is the only thing that is gonna get you better mileage to any significant degree, and they are so expensive as to make them impractical if all you want is economy. I would recommend getting a 4 cylinder Ranger for economy and using the F150 when you need to haul a load or pull a trailer. The best way to get the best mileage is to use the right vehicle for the right job.

Back when my truck was my only form of transportation and I put over 30K a year on it
mileage was one of the things I strived for with mods. I did an intake and
exhaust and got nothing out of it for mileage, same with a tuner but I do
not use an economy tune. Electric fans gave around 1mpg and a
tonneau cover did about the same.

More agreement here. The CAI and exhaust will only help when the engine is trying to take in and let out more gases--basically at high RPM's. At light throttle settings, the butterfly in the throttle body is holding the air back. And slightly warmer intake air will actually atomize the fuel better.

Keep a clean air filter in it. Keep the tires aired up, maybe with a couple lbs more than the stock recommendation.

If it's time for new tires, get something with low rolling resistance and in a stock size (Michelin LTX M/S's are a great tire as an all rounder with low rolling resistance, and the new BFG Long Trail TA Tours are very good as well). Heavy and blocky treads use gasoline to flex rubber if you're on the road.

And do what you can to keep your speeds lower if you can (hard for me to do when I'm trying to get to work on time), anticipate stops so you're not on and off the throttle more than needed. Every time you use the brakes, you waste momentum, which equals gasoline.

And some aero mods like a tonneau cover could help but the $ payback will take a while. You could do weird stuff like chin spoilers but that's not practical...

Good luck,
George

Thanks all.

I might remove the tailgate.

I want to do the flowmaster muffler with my truck, so I will go ahead and do the dual exhaust and maybe a drop in K&N filter. I want the sound, lol.

I won't look for the MPG increases and that's fine. The truck is getting 15.43mpg and that's mixed city/highway.

Don't you watch the show Mythbusters? You'll get better mileage with the tailgate closed. :)

That's funny. I won't remove it then.

Is the 15.43mpg bad for the truck?

I would say for mixed driving it's about normal.

Let me give you another way to look at this.
The motor design is such that it would be hard to improve the hardware without very high costs.
It's not like the old motors that responded to intakes, headers etc so easily.
Next the motor is controlled by a computer program that receives inputs from sensors that you could not change to any usefull degree with hardware changes.
The next two items are the bigger reasons for the average mileage we get.
They are the motor size (262 cu/ in) quite small and the weight plus areodynamics.
Bottom line is you can't get anything out of air intake changes and not much out of any exhaust changes.
Now both these areas will show improvements but at high RPM where you don't normally run at.
Note that even the new motors are not running at huge increases in fuel mileage.
What improvements they do offer is from camshaft phasing changes through the RPM range and a small increase in compression to make the motor more efficient with alky based fuels.
So you can see that trying with the costs of it on your truck a loosing effort.
After market mfgers will tell you about the increases their parts will give as a sales pitch by demonstrating air filters restriction differences on a display but the average owner has no background to know the real story.and gets sucked in by it.
For example, even taking the stock filter (((out))) will not make any improvement in mileage. Why; because the throttle body controls the airflow at all speeds less than wide open, not the air filter.
As to exhaust, the stock system is somewhat tuned for the average truck use such that you could even lose torque if it is changed because it may change the resonance tuning as designed into the system by Ford.
Bottom line is these systems today are not user friendly to change unless you understand all the relationships and have the resources implement them, bypassing all the factory design and long term testing they do before it goes to the public.
Lastly, the PCM program has a high degree of conservatisim for reliability to insure the product is not able to be abused by an owner to the risk of degrading FMOCO reputation in general.
So it's in this area you can get aftermarket changes that can improve power and mileage to some worthwhile degree but it's cost is even quite high and to some degree risky when things may go wrong and some one has to take resposibility for it when the finger pointing begins.
Good luck and happy holidays.

i have an 03 supercab with flowmaster cat backs and the k&n with a 5 speed tranny and thats pretty much the same mileage i get city and back road driving with courser 265/75/16 msr tires and 3.55 gears. economically its not worth really changing as the end result is minimal at best, i pull a utility trailer with it and fully loaded it weighs in around 3000lbs and the truck pulls it just fine but for mileage you wont do much better than what your getting now. truth be told the 6 or7 hundred you'll spend for the k&n and flowmaster system will buy a lot of gas or make a nice start at saving for a more gas efficient vehicle.

I get ~15 mpg mixed country roads and highway with 265/75r16s, 3.55, bed cover and 4.6 with auto. Its a single owner truck and seem to remember that it got ~16 mpg from day one. I was able to get 19 one time living in texas but I committed to not exceeding 55 mpg just to see what the best I could do when the truck was new - that was with the small highway tires that came stock.

Last week, I was able to get 17.5 mpg - the best mileage Ive gotten in years. I did this since most miles were highway miles (65-75 mph) but with ethanol free gasoline. Luckily I just moved close to an ethanol free gas station and after the 2nd tank I think that fuel has increased mpg by 1-2 mpg (~10% mpg improvement for $0.10/gal (4%) cost premium.

If you can find ethanol free gasoline, thats going to be better than any aftermarket mod you can do!

You didn't mention how many miles are on the truck.
Here are a few things to consider replacing:
Spark plugs, coils, fuel filter, and air filter.
Clean the air intake system including the mass airflow and air temp sensors.
If mileage is near or over 100K, replace the oxygen sensors.
Correct size tire and type with proper inflation. I have BFG Long Trail T/A and maintain 42 psi front and rear.
Add 4 ounces of Lucas fuel system cleaner at next fuel fillup. More is not good and can damage good O2 sensors.
Restrain yourself from hotrodding the truck. I know it is tough.

The 2000 in my signature achieves between 16 and 20 mpg depending on the amount of highway driving and my behavior.