2003 Ford Expedition build thread
 

Hello everyone. Recently I sold my Dodge Dakota and Ford Explorer and purchased a 2003 Expedition. This was definitely a step backwards in fuel mileage but makes more sense in my needs.

Anyways I plan to keep this thing for a long while and do quite a bit of modding. First simple things I did was upped the tire pressure to 40 psi and removed the luggage rack cross members. My first 2 tanks have yielded a little over 14 mpg...not so great.

Some future stuff I plan to do (in no particular order):
Injector kill switch/pushbutton start
Alternator cut off switch/deep cycle battery
Electric fan conversion
Grille blocks/front air dam/belly pan
2 inch lowering springs
Switching from 265/70/17 tires to 255/75/17 tires or 265/70/18 wheels + tires
Possibly changing front/rear differentials from 3.73 to 3.55 or 3.31

I would love to hear feedback, ideas, comments, concerns, hatred, whatever you want to say.

Don't tell me its 4wd too...

Go big or go home when it comes to gearing changes.

My mom used to drive a 2012 Explodition EL, she would get 14 mpg with it. She now drives a 2015 Mazda CX-5 and gets 26 mpg.:) When delivering birdseed with it in essentially ALL CITY driving with lots of stops, me and my older brother would get 13-14 mpg with it. I once squeaked over 20 mpg with it in a city trip, probably the only time that suicidal utility vehicle ever broke 20 mpg in our ownership.

Are you still a mobile mechanic? I would think that a car with a trailer to hold all your tools would be more efficient, but you already made up your mind. Thankfully you came here to find out how to burn less fuel, so we will give you credit for that.

I would focus on things that would help that big engine/transmission warm up faster. Get a block heater and an oil pan heater. Consider making an adjustable grill block and have it completely blocked during warmup. Definitely do the electric fan swap.

There will be plenty of drag from those big tires, if you can make optimized tire deflectors then you can drop tire drag a good bit, and without adding any frontal area.

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Big suicidal utility vehicles like that are known for eating wheel bearings, check yours. Check the brakes too of course, and consider making some brake drag reduction springs.

Yes unfortunately it is 4wd. I looked for 2+ months to find either a 2wd Tahoe or Expedition and just didn't find what I wanted. This one has almost no rust and the price was very reasonable.

I still use my Windstar for work, and it is perfect for that. I kinda let its ecomods stall out but I still use the kill switch and starter and aeromods on it.

This will be used for hauling family/kids and towing cars and eventually a camper. My Dakota was just too small for people and the Explorer didn't have the towing capabilities I needed. If nothing else I have less insurance and maintenance overhead.

I agree with the additional aero mods and the fan swap. I also had the idea if I do change the differentials I could use a significantly smaller tire like a 235/70/17 which would also lower my ride height and kinda reverse the differential change but help with rolling resistance and aero drag.

One selling point on this truck was the front bearings/brakes/calipers/hoses were all replaced a year ago. I plan to replace all the brake lines and rear brakes in the next few months.

That may be good, even though my first and only attempt of EOC in a vehicle with automatic transmission was quite scary to say the least...


Even though some folks claim to do it fine with an alternator delete, I still consider it quite risky. But anyway, would an underdrive pulley be out of question?


An electric fan is a quite cheap and easy mod which usually tend to have a great cost-effectiveness. Go for it.


Independent rear suspension might make it easier to overcome driveshaft clearance issues with a full-lenght belly pan :thumbup:


Lowered SUVs, especially 4WD ones, look quite odd.


Possibly the 255/75/17 would still be better than the 265/70/18 due to a (slightly) lower weight and the narrower tread. But anyway, since you're already considering to swap differentials for taller ones, getting a set of tyres with a larger diameter might become redundant at some point.

I never even thought about an underdrive pulley. I had one on my Dakota. Alternator delete scares me and wouldn't be practical for any future cross country camper trips.

I think this thing looks odd sitting as tall as it does. Seems like there is 6+ inches clearance in the wheel wells.

I will need tires before next winter so my hand will be forced in the next few months. If differentials happen I will probably stick with factory size or even go down size.

I did some ripm's calcuemalations, and with the stock tire size:

70 mph__

3.73 - 1943 Not bad!
3.55 - 1850
3.31 - 1725

45 mph__

3.73 - 1249
3.55 - 1189
3.31 - 1109

Oh yeah, and I do vote for keeping the stock tire size, or maybe going down to the 255/75/17, I wouldn't suggest going much smaller. As far as studies I have seen, larger tires DO have lower rolling resistance(how?), but I haven't narrowed that down to width vs rim size. If you are going to do lots of highway driving, then the reduced drag from thinner tires will probably outweigh the RR difference.

My gearing vote is still on go big or go home.

Before you get new tires, check the spare. If its really old, then it would be best to put the best old tire on the spare wheel.

Underdrive pullies are great, meziere electric water pump is an option too, and you might be able to swap to an electric steering rack off of the new f150. i say this because my dad did all that to his 08 Mustang gt and the thing is quick! (2011-14 EPAS swap, UDPs, Meziere EWP, and some more stuff) and gets 29mpg out an auto going 70 down the interstate. Past that Aero the crap out of it and maybe bump the tires to 50.

That makes sense.

Look what I found rolling around my basement. Well I knew it was down there. Fan itself measures about 16 inches. Shroud is 21x23. The Expedition radiator core is 19x27 so it should cover pretty nicely. Or I could trim the fan shroud to fit the Expedition's shroud. Not sure which way is easier/better?

One uncertainty is the fan has 3 wires so I'm not sure what the extra wire is for? Maybe a low speed/high speed? I think it's from a Durango or Grand Cherokee but I honestly don't remember.

And I've got the differential bug I think. Can pick up a used rear 3.31 for $200-300 and front for $150-250. My generation Expedition never came with a 3.31 front end so I am looking at a previous generation. I think the axles will bolt up to it but I guess I will cross that road when I get to it. Or I have to splice axles together.

I think I will start by changing just the rear and just keep the truck in 2wd and it should be fine. Anyone know for sure? Certainly don't want to roast the transfer case. If that goes well I may drop down to a 245 70 17 tire which should be approximately 1 inch smaller in diameter so 1/2 inch lower ride height. Then if I do the 2 inch lowering springs my ground clearance should still be 6.5 inches.

Well I am 2 for 2 on having free stuff. I measured the resistance of the fan and came up with 1.0 ohm between 2 of the wires. The controller I have is rated for 16 amps so that should work fine. The third wire is still a mystery as it had around 150 ohms to both other wires. Only thing I can figure is it was some kind of return signal to the ecm or a controller. Maybe returning fan speed and it would adjust voltage up or down to the fan. At any rate I'm just going to leave that wire unattached.

Took a quick glance at the engine bay and was a little surprised to find no fuse box under the hood. Guess I will have to run a ignition power wire from inside unless I find something else under hood. My rough measurement of the inside of the shroud is 21-22 inches so with a little trimming I think I can mate the electric fan to the existing shroud.

I got busy this morning and afternoon installing this fan. First I tapped into a wire that was hot with key on.

Then found a nice spot to mount the adjustable fan controller.

The fan mated nicely to the oem shroud. I know its not a perfectly sealed fit but it should work well. It has 3 bolts with double nuts with an old sway bar link bushing sandwiched between the two shrouds to limit vibrations.

And my semi final wiring mess. I will clean things up a bit once I am certain everything works how I want it to.

This fan is an absolute beast. It pulls somewhere between 30 and 40 amps. I know this because it will blow a 30 amp fuse. I matched the wire gauge with what was on the fan already. And I manually ran the fan for about 5 minutes and the wires and relay didn't show any signs of warming up so I feel good about it. I noticed the truck warmed up significantly faster than I recalled before...but it was also almost 60 here today instead of 30s-40s.

What engine does it have 4.6 or 5.4? I'm assuming these are just about the same as a f150 if so 20 mpgs should be easily attainable with a few mods. My 99 f150 gained about 2 mpgs from switching to an electric fan so that's a good start. I also recommend a lawn edging air damn extension, synthetic fluids in diffs and transfercase, upper grill block and 12 hole injectors

Filled up this morning for my first tank with the electric fan conversion. Didn't see any improvement but I know its a step in right direction.

Cut out some coroplast pieces and spray painted them black for my upper grille block. I realize they would be better in front of the grille but I'm opting for the better cosmetic appearance over efficiency on this one. Shoot me.

Planning on picking up a used 3.31 rear end in the next week or so. Then it will be a matter of finding time to install the damn thing. On a related note does anyone have any recommendations for a tuner that can correct the speedometer/odometer once I do the change?

5.4 unfortunately. Keep in mind the Expedition is a good 1000+ lbs heavier than an f150. And a lot of f150's have a taller rear end ratio.

Wow had no idea they were so heavy. If you want to have a manual a m5r2 out of a f150 should drop right in and if u can find one that's rwd you could lose the transfercase front diff and axles that should save At least 100lbs and have less drivetrain loss

According to what I have seen online they are around 5600 lbs. I wouldn't be against a manual swap but everything works fine as it is now so I have no plans to rock that boat. Sounds like a lot of work..cause it is a lot of work.

You have a point some how these Ford's make what should be a small easy job into a grueling task

Wouldn't say its a Ford thing just more fabrication that I want to mess with. Driveshaft, mounts, shifter, entire clutch system, linkages, computer issues?, etc etc. With this being more or less a daily driver I can't really have it down for a length of time.

Seems like my grille block is working. I have my 3.31 rear diff ordered, just waiting for it to come in. I also scored some FREE 245 70 17 tires that are nearly new. They are all terrain tires which isn't really what I wanted but free is free. Not sure when I will have time to get everything installed but at least heading in the right direction.

Been lazy about updating on here.

5/12-5/13 I installed the 3.31 rear end. Everything went pretty well. Tore it apart on Saturday late afternoon/evening then finished it up Sunday morning. My scary looking brake lines reared their ugly head when I went to test drive by blowing out the rear line so my hand was forced to replace that. I also removed the front driveshaft since the front diff is still 3.73.

5/17 I got my programmer to correct the speedometer. It is a "power programmer" and it feels like it improved throttle response and transmission shifting immensely. I have a slight concern that has actually hurt mileage but its fine for the time being.

5/18 I installed a manual switch for my electric cooling fan. Mainly did this for A/C performance at low speeds/parked.

5/19 Unfortunately I had to replace one of the axles seals in the rear end. Guess that's what I get for being cheap/lazy and not replacing them while it was on the ground. Other side is not leaking so will leave it alone for now.

5/19-5/20 We took a trip to Michigan. Got about 50 miles from home and the truck totally shut down. Found that the ignition switch fuse had blown. I hastily cut the wires for my manual fan switch. My suspicion is that somehow it back fed through the ignition switch fuse and blew it. Will have to rethink my wiring when I get back to reinstalling.

I feel that the 3.31 rear is probably a little tall. But my plan to go to a smaller tire size will offset that. On the highway it is very sluggish to accelerate without kicking down a gear, which I expected but I feel it is too much.