My quest for better fuel economy...

[MikeTX]

So like the title says, Im on a quest for better fuel economy. Right now, my 1999 XLT 2WD on 31's with a 4.0 SOHC is getting absolutely piss poor gas mileage. In town, Im lucky to get 10-12 mpg and maybe 16 highway. I know 31's aren't helping matters, but I like them and got a killer deal, so thats what's on there.

I've read through alot of threads about hypermiling and better fuel economy, including Aldive's famous 30mpg thread. I know I'll probably not get that out of a lifted, 173k miled vehicle, but still. If I can get 20+ on the highway, I'll be happy.

I've switched over to full synthetic oil. I'm planning on changing trans fluid to full synthetic, and hopefully even the rear diff. What concerns me with that, is I've always been told that with the transmission on a high mileage vehicle, that if you change the filter and fluid, that you can start having problems. I'm wondering if this is true at all, because in all the things I've had to do mechanically, draining and refilling a trans with new fluid isn't one of them.

I've got an intake, but its basically just a cone filter on the stock hose between the MAF and TB. Would changing to aluminum pipe really make that much of a difference, because honestly the cone filter only seemed to hurt fuel economy to the point, I've considered just putting the stock box back in.

The exhaust, I'm just planning to cut the muffler out and leave the factory resonator for now to eliminate the refrigerator sized OEM muffler.

I'm also planning on swapping the stock clutched fan for an electric unit from a Taurus. I want to keep the mods cheap until I see if they make that much of a difference, so I'm thinking about skipping the thermostat controller for the fan for right now, and just running it hard wired through a relay to constantly be on with the truck. Would that be a problem? I mean, with summer coming on here in Texas, I wouldn't think it would be, but I'm not real sure. Only time I've been in a car with a setup similar was my grandpas old car back probably 25 years ago. Would it hurt anything to run it that way?

Sorry for all the questions, I'm just hoping yall have more experience in this department than I do.

 

[Centaurus5.0]

I'd would suggest installing a good 'dry' air filter and cleaning your Mass Air Meter. If the o2 sensors are stock 173k, id get set of those too. I don't know much of anything about V6's, but if the injectors are easy to get to I'd replace those as well.

That should make a world of difference.

$10-40 Air Filter
$12 CRC Cleaner
$80 o2 Sensors
$80 Reman Injectors

And for only $200, give or take...

 

[chefduane]

C5.0 has pretty good advice. I have an AEM air filter in my '98 and I did the 'swiss cheese mod' to help her breath a little bit better. Clean the MAF with CRC also. If you don't want to actually change injectors, you could run a few bottles of Techron through the tank. If it makes you feel better you can Seafoam it through the brake vacuum.
I also run Hi-Mileage Mobil-1 full syn and a Mobil-1 oil filter. The Ex is never going to be a high MPG vehicle. If you want that, get a Kia.

 

[MikeTX]

Well I bought mine with 165k on it and did a full tune up on it right away. High mileage full synthetic oil and good filter, plugs, wires, coil pack, intake manifold gaskets, pcv valve, replaced a couple worn injectors, Seafoam through the brake booster and through the tank as well as some injector cleaner, cleaned the MAF, cleaned the TB, and replaced the fuel filter.

I haven't changed the O2 sensors yet, but probably should. I'm not looking for ridiculous mileage, I just want better than what it's getting because i know it should get better mileage. Like I said, if I can get closer to 20 highway, I'll be happy.

 

[chefduane]

Sounds like you've done all the right stuff. I assume you're running a quality fuel? (We do get fairly good stuff locally in DFW - comes up usually from Houston). Dunno what else to suggest.

 

[96ex5.0]

Gears would help, it may be working a bit to hard to turn your tires especially if there 3.55 or higher gears

 

[MikeTX]

Yeah, I have a buddy who works in oil and gas and we had a long talk once about which stations use gas made in America from American oil supplies. Since then, those are the only stations I go to.

I'm not even sure what size gears are in the rear end. But I was really hoping to not have to go that invasive to get better he mileage. Lol

 

[swshawaii]

I'm not even sure what size gears are in the rear end.

Select vehicle, enter VIN, click minor features for more details. Axle ratio shown in primary features.

https://www.etis.ford.com/

 

[MikeTX]

Thanks for that link swshawaii! I've apparently got 3.73 gears. What would be a good gearset to look into?

 

[chefduane]

I have the 3.73 LSD rear end in my '98 4x. My Ultra Gauge calculates my highway mileage (I don't do much in town driving) as 18.6mpg. I don't really believe that tho. I have calibrated it a few times and still get the same results. Go figure.:scratch:

 

[MikeTX]

I have the 3.73 LSD rear end in my '98 4x. My Ultra Gauge calculates my highway mileage (I don't do much in town driving) as 18.6mpg. I don't really believe that tho. I have calibrated it a few times and still get the same results. Go figure.:scratch:

What size tires so you run?

 

[chefduane]

Stock P235/75r/15's. Goodyear Wrangler Radial A/T. Nothing special.

 

[meyek91974]

So like the title says, Im on a quest for better fuel economy. Right now, my 1999 XLT 2WD on 31's with a 4.0 SOHC is getting absolutely piss poor gas mileage. In town, Im lucky to get 10-12 mpg and maybe 16 highway. I know 31's aren't helping matters, but I like them and got a killer deal, so thats what's on there.

I've read through alot of threads about hypermiling and better fuel economy, including Aldive's famous 30mpg thread. I know I'll probably not get that out of a lifted, 173k miled vehicle, but still. If I can get 20+ on the highway, I'll be happy.

I've switched over to full synthetic oil. I'm planning on changing trans fluid to full synthetic, and hopefully even the rear diff. What concerns me with that, is I've always been told that with the transmission on a high mileage vehicle, that if you change the filter and fluid, that you can start having problems. I'm wondering if this is true at all, because in all the things I've had to do mechanically, draining and refilling a trans with new fluid isn't one of them.

I've got an intake, but its basically just a cone filter on the stock hose between the MAF and TB. Would changing to aluminum pipe really make that much of a difference, because honestly the cone filter only seemed to hurt fuel economy to the point, I've considered just putting the stock box back in.

The exhaust, I'm just planning to cut the muffler out and leave the factory resonator for now to eliminate the refrigerator sized OEM muffler.

I'm also planning on swapping the stock clutched fan for an electric unit from a Taurus. I want to keep the mods cheap until I see if they make that much of a difference, so I'm thinking about skipping the thermostat controller for the fan for right now, and just running it hard wired through a relay to constantly be on with the truck. Would that be a problem? I mean, with summer coming on here in Texas, I wouldn't think it would be, but I'm not real sure. Only time I've been in a car with a setup similar was my grandpas old car back probably 25 years ago. Would it hurt anything to run it that way?

Sorry for all the questions, I'm just hoping yall have more experience in this department than I do.

Where is the Aldine 30mpg thread???

 

[swshawaii]

^
Aldive's Mileage Monster | Ford Explorer and Ranger Forums - Serious Explorations

Epic EF thread. Does it disclose how much time and money was spent to achieve 32 highway MPG?