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peakay · 11-16-2009, 01:38 PM

Hi there,

We own a Ford Expedition and I'd like to modify it to see what kind of improved gas mileage we can get.

*** Before I go further, please keep the flames and snarky comments to yourself. I realize this is a ridiculous vehicle from a MPG standpoint, but given the economy it is not one we are in a position to replace at the moment.

Anyway, its a 2005 2wd model and currently gets 13mpg city (my wife drives it) and 18mpg highway. I would love to get it to 20 and over highway and at least up to 15mpg in the city. I've been studying the Chevy Tahoe hybrid and it has a lot of mods to it for mpg that have nothign to do with the powertrain.

here are the mods I'm considering - feedback please:

1) remove roof rack (doesn't have crossbars - is it worth doing?). Tahoe hybrid does not have one.

2) remove spare tire and related jack tools. Does anyone use Slime as a preventative product or carry it in case of flats? With the size of these wheels, it just seems ridiculous to carry an extra one one around. Tahoe hybrid has runflats. FYI our current wheels are 18" wheels off of a lincoln navigator that look like this and are pretty flat on the face.

3) lower the ride height. the 03+ models are the same height whether 2wd or 4wd, but there is no reason for it to ride as high as it does. Are we likely to see an aero mpg gain on the highway? I wouldn't mind having the step in height be lower anyway and the springs are a little stiff on initial jounce, so maybe a progressive lowering spring may even ride better??

4) front air dam. Tahoe hybrid has a pretty massive one that hangs down fairly low. Ours looks like the one in this photo and you can see that the license plate needs to go and there is a decent lip to mount some lower material.

- would it be a good idea to mount a lower lip here or would it increase the size of the front end too much? If it would be, where can you get some material to mount here? Does anyone make some plastic to use for this purpose?

- What should I use to cover those huge lower holes (I believe they are for tow hooks on the 4wd model)? Might also try blocking that lower grill -- not sure if we need so much air intake.

5) re-map the throttle response? I can get more mileage out of it with a light foot, but for my wife it would be better of the throttle was remapped so that it didn't give as much throttle when you barely touch the gas. can this be done?

6) Gear ratio. We currently have a 3.73 rear diff ratio which could be lower. It cruises at around 2k rpms on the freeway. Due to cost and complexity, a gear change may not be in the cards, so what is the current thought on taller tires? Any benefit or do you lose it based on having to turn taller/heavier tires?

That's it for now - I really appreciate any and all constructive feedback!!

11-16-2009, 01:38 PM	#1 (permalink)
peakay EcoModding Lurker Join Date: Jul 2009 Location: Southern California Posts: 5 Thanks: 0 Thanked 0 Times in 0 Posts	Modding Ford Expedition Hi there, We own a Ford Expedition and I'd like to modify it to see what kind of improved gas mileage we can get. *** Before I go further, please keep the flames and snarky comments to yourself. I realize this is a ridiculous vehicle from a MPG standpoint, but given the economy it is not one we are in a position to replace at the moment. Anyway, its a 2005 2wd model and currently gets 13mpg city (my wife drives it) and 18mpg highway. I would love to get it to 20 and over highway and at least up to 15mpg in the city. I've been studying the Chevy Tahoe hybrid and it has a lot of mods to it for mpg that have nothign to do with the powertrain. here are the mods I'm considering - feedback please: 1) remove roof rack (doesn't have crossbars - is it worth doing?). Tahoe hybrid does not have one. 2) remove spare tire and related jack tools. Does anyone use Slime as a preventative product or carry it in case of flats? With the size of these wheels, it just seems ridiculous to carry an extra one one around. Tahoe hybrid has runflats. FYI our current wheels are 18" wheels off of a lincoln navigator that look like this and are pretty flat on the face. 3) lower the ride height. the 03+ models are the same height whether 2wd or 4wd, but there is no reason for it to ride as high as it does. Are we likely to see an aero mpg gain on the highway? I wouldn't mind having the step in height be lower anyway and the springs are a little stiff on initial jounce, so maybe a progressive lowering spring may even ride better?? 4) front air dam. Tahoe hybrid has a pretty massive one that hangs down fairly low. Ours looks like the one in this photo and you can see that the license plate needs to go and there is a decent lip to mount some lower material. - would it be a good idea to mount a lower lip here or would it increase the size of the front end too much? If it would be, where can you get some material to mount here? Does anyone make some plastic to use for this purpose? - What should I use to cover those huge lower holes (I believe they are for tow hooks on the 4wd model)? Might also try blocking that lower grill -- not sure if we need so much air intake. 5) re-map the throttle response? I can get more mileage out of it with a light foot, but for my wife it would be better of the throttle was remapped so that it didn't give as much throttle when you barely touch the gas. can this be done? 6) Gear ratio. We currently have a 3.73 rear diff ratio which could be lower. It cruises at around 2k rpms on the freeway. Due to cost and complexity, a gear change may not be in the cards, so what is the current thought on taller tires? Any benefit or do you lose it based on having to turn taller/heavier tires? That's it for now - I really appreciate any and all constructive feedback!!