Ya know, they aren't reallt broke in until you have 5,000 miles on the clock and at that point you will see better mileage. Twice in a row I have found this number to be magical. For that matter, it seems to take about 10,000 miles for the final and best result.
Billy's right...ya gotta get that puppy broke in first and then you just may find that your best gas mileage improver is your own right foot.
Many people advocate the addition of a free-flowing exhaust system to improve both power and economy, but it can be a double-edged sword. You may find your mileage drops after such a mod, and it's usually because you find you like the sound when you get on it and so you put your foot in it more frequently. It's not till the novelty wears off that you see the improvement, and that's only if you can discipline yourself to drive with a light foot.
And please, don't waste your money on the mileage improvement devices. Fuel line magnets, Tornadoes and such are just scams.
There are alot of things that are debatable, but I will tell you what worked on my 04 ranger 4.0. A free flowing intake, and exhaust, swapped in synthetic fluids from the motor to the rear diff. One of the biggest helps, was the bama chips programer, I have an 87 octane mpg tune, but on the other 2 higher octane tunes, the mpg went up as well, as long as you drive right. Does the cost of the higher octane gas out way mpg increase ? Still undecided, but it makes it easier to swallow as I bought the programer for the performace benifit, better mpg is just a bonus. Besides spending money to save money (oximoron) don't carry around alot of unnesesary weight, and make sure the tires are properly inflated, and as the gang has stated, let it get broke in.
drive like there is an egg on the gas pedal....keep rpms below 2,500 the torque peak on the 4L.....let off gas and coast to stops
not WOT pedal to the floor runs....use OD, TC lockup and the tranny coast clutch as much as possible, any other gear sucks gas...
drive speed limit only
80 mph freeway with 4wdr Explorer makes the oil shieks fat and greasy rich, 15 mpg or less
Here's my experience so far, for what it's worth. I have an '06 Explorer 4.0L 4x4, 3.55 axle. 5400 miles on it. Mileage has gone up from 16.5mpg on the first tank to currently 19.3mpg average over the last 3000 miles, mostly (probably 90%) highway. Under 65mph gets me about 20.5. 75mph seems to be about 18.5. In the city it drops off fast. I don't want to know.
I am cheap so keep that in mind when considering my mods. I noticed that the air intake sits behind the grill. A great cold air location using the factory airbox. Problem is that there is a plastic dam betwixt the two. It is surely to prevent water aspiration during downpours? Anyway, I popped the grill out and cut a hole in the obstructing plastic. I always put fly screen over the radiator area anyway to keep the bugs out so when I did I cut a piece big enough to go over the air intake as well. Then I drilled a drain hole in the bottom of the airbox for any water to get out. I think it makes a nice ram-air setup. Granted, I am still using the factory filter. I can't say that I have noticed any difference in performance but it has to be better than it was ...right? Anyway, in my past experiences with a GM 6.5L diesel and current Ford 7.3L, mileage and power increases came with a free flowing muffler, a full two mpg improvement. So that is my next project. I plan to keep the factory piping and go with only a new muffler. Remember, I am cheap. Also, I am thinking that keeping the existing pipe will keep exhaust velocity up and keep me from losing torque. There isn't any extra with 3.55 gearing.
I appreciate when I hear others' personal experiences posted like Wendell did. Sorry I don't have more to offer yet.
An 18.5 average is definately range for good MPG. It will cost to invest some money into an exhaust upgrade and intake...if you do it before the 10,000 mark you'll have a lot of time to enjoy the performance and MPG gain with any upgrades.
Since your doing 75% highway,25% city driving, pick up a K&N air filter, it should give 1 MPG increase for those driving habits:
with all the blowing dust, desert grit there in NM, stick with the factory air filter cartridge....Motorcraft is the best for micron filter quality and has at least 3 times the air flow that the engine requires at WOT....K&N's leak dust grit particles thru and will contaminate the MAF with oily products if not perfectly oiled....run a U.sed O.il A.nalysis and look at the silicon values go up with any of the cloth diaper filters
even the Baja racers don't run cloth filters...they may have them mounted up top with a fake air feed to engine and a big advertisement sticker but down inside where the copilot can change it is a real paper high filtration filter
Thanks 96_4wdr, for the tip. I used a replacement K&N on our prior Expy for a while. I never had an oil analysis done but did have a nagging uneasiness about filtration. I didn't like the cheap foam seal with sticky tape holding it on either. I had to be careful getting it in just right. Eventually I went back to stock for those reasons. I'm still not thrilled about factory airboxes though. I like the definite seal of hose clamp style filters, but not so much that I need to get one (with either paper or gauze). I pretty much figured that stock airflow is plenty for a truck that hasn't been modded for buku's of hp. I didn't realize it was 3X though.
Same goes for exhaust. On my powerstroke the stock piping is plenty big. It was the muffler that was the weak link. No reason I have seen for me to think differently for the Explorer.
Jam66, you started this thread trying to improve mpg's. I see you are also looking to get bigger tires. That won't help. Realize there is a trade-off and if you do multiple things at once you won't know which changes have what effect. Not bashing you, bigger tires would look good.