A better engine for a 2003? | Ford Explorer Forums - Serious Explorations

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A better engine for a 2003?


July 5, 2015
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Year, Model & Trim Level
2003 Ford Sport Trac
I’m the somewhat disappointed owner of a new to me 2003 sport trac 5 speed. The truck is in immaculate condition and sized just about right for what I want to do with it. Problem is this 4.0 is very thirsty, to the tune of 19mpg highway; EGAD! Has anyone done an engine swap for a more fuel efficient engine in this little beasty? My wife’s 2014 Mustang gets as good as 32mpg with daily to work travels and has power to spare. This little truck has neither in great abundance; gutless and no economy.
Your thoughts please,

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2WD or 4WD? Check the final drive ratio on the door jamb tag. Ratios are as follows:
41 - 3.27 non-limited slip (Explorer/Mountaineer)
45 - 3.55 non-limited slip (Explorer/Mountaineer)
46 - 3.73 non-limited slip (Explorer/Mountaineer)
42 - 4.10 non-limited slip (Explorer/Mountaineer)
D1 - 3.27 limited slip (Explorer/Mountaineer)
D4 - 3.73 limited slip (Explorer/Mountaineer)
D2 - 4.10 limited slip (Explorer/Mountaineer)

I've got a code D2. Nice low end torque, but crappy gas mileage. You may have the same. A step up to a 3.27 ratio will give the MPG a boost, but will do nothing for your feeling of acceleration.

Hopefully somebody else has a better answer than me, but mine is "no, you're screwed". The 3.7 your wife's car has is a totally different beast, Ford really has their shiz together with much of their powerplant lineup these days. Maybe there's a way to get a 3.7 or one of the EcoBoost engines in but I can't imagine it being inexpensive or easy. Also worth considering is that her car is 700 lbs lighter, more aerodynamic and the 6 speed transmission helps a bit as well.

19mpg's not bad for a truck. I barely get 18 in mine. My '06 Ranger regular cab with a 2.3 that I used to have only got 21-22, and you don't know the meaning of "gutless" until you've spent 6 years in one of those.

My axle code is 46.
I sort of figured I'm stuck with it. Burns me a bit since my brother-in-law's F150 4-door is getting close to 22mpg!
I was hoping for a "Engine x makes for a good swap" sort of answer but sometimes those just don't exist.

Yep, the fuel economy on these trucks sucks, buy hey - gas is super cheap right now. Enjoy it.

engine tech has come a long way since the days of our single overhead cam iron block v6's. the 3.7 in your mustang has dual overhead cams and variable valve timing; your neighbor likely has the 3.5 ecoboost (dual turbo) or a 5.0 (coyote motor, again VVT). these are much more advanced and modern engines.

our motor is based on the ford 2.9 cologne v6 which dates back to the early 80's.

19mpg is about as good as you're going to get. I get 16mpg on a good day.

my advice is to buy a focus, and enjoy your truck for being a truck.

Well, Goshawk, you just got it, so my question is have you done the basics first, yet? Fresh tune-up with all new ignition parts, filters, all fluid changes, tire pressures to spec, etc., etc.? Are you an easy driver or a lead-foot? Re-evaluating all these factors may well play into improving your economy. Does the vehicle have a maintenance history? If you think you're disappointed now and you don't do your own maintenance you're going to be pissed off when you're getting things like ball joints, bushings, cooling system parts, timing chain issues, body mount bushings, and fuel pump problems jumping out of the wood work.

I bought this little guy with 80,000 miles on it from a gentleman who did not know it had a low range. It's been a city truck.
I went through it and did a full tune up, wheel bearings and swapped out the muffler.
It had a very good stainless duel exhaust system, but with a super loud muffler that made it sound like a rapped out & lowered Honda car.
The after market wheels were oversized with thous little narrow bands of rubber that can't absorbed road vibrations. All the wheel bearings were consequently destroyed.
So, yes I've gone through both engine maintenance as well as drivetrain improvements to bring it back to a usable hunting and winter trip truck that won't make you deaf to drive or leave your hands feeling like you've been running a chainsaw! Wish I could add manual locking hubs to help out with the fuel millage.

Sure wish I could sell these tacky wheels...

19 MPG with 4:10's is about as good as it gets. I'd be happy to see this MPG on my '01 ST and it's only 2WD. If you want great MPG buy a new Fusion. There are no Ford engines that would be a direct bolt-in that will give you better MPG on a ST. If you were a hot rod/fabricator, a new V6 Eco-Boost would make an interesting swap.

There's someone swapping a 3.7 V6 into his on here, but it's a lot of different tasks and wiring headaches. The only motor that's close to bolt-in for these trucks is the old 5.0 from a 2nd gen Ex/Mounty, but that's not going to improve mileage at all. It's kind of funny seeing 19mpg as bad (not meaning to offend, more laughing at myself) as my Trac hasn't seen higher than 16mpg and I also have a 9k lb F350 that doesn't get over 18 very much. I'd be ecstatic with 19! Maybe you can get a diesel Ranger in the next year or 2 when it comes to the States.

Well, that pretty much answers my question.
Thanks All,

I wish I was getting 19 or even 17 mpg's but I average 13.

One last thing.
Part of my question comes from another observation. Last fall the family rented a 2015 Dodge van, loaded four adults, one child and all the gear that goes with a 7 month old. We got an amazing 28.5mpg on a 1,000 mile road trip from Olympia to Boise Idaho and back. That's the same route I'm getting 18.8mpg with the Sport Trac. That van had all the power and economy I could have asked for.

Just seems like there should be a way to close the gap between the two.

As stated change the axle ratio and a taller tire can gain you some better fuel economy. A manual transmission swap could gain you a small increase in fuel economy, it did on my van.

I already have the tallest gears at 3.73 and a manual 5 speed, so as written earlier, That's about as good as it's going to get. If I put taller tires on it, I'll have to run it in low range just to go up a hill.