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best ways to boost mpg?

moparmansfield

moparmansfield

NAXJA Forum User
Location
Portland
im using my 01 xj for work, im a service tech that travels all around the bay area, and i drive on the average of 150 miles a day or more. im trying to get as much gas mileage as i can. it seems to be getting pretty bad mpg right now, around 12-15. im running a 3.5 lift with 31's, 3.55 gears. all i can think of is open up the exhaust some and put on an air intake. are there any other options i have? any help would be great.
 
Buy a Prius :D







Seriously though, air intake, exhaust, neon injectors, bored TB, and be easy on the skinny pedal I drive like a grandma and it helps my MPG's out ALOT
 
rweaver138 said:
Buy a Prius :D







Seriously though, air intake, exhaust, neon injectors, bored TB, and be easy on the skinny pedal I drive like a grandma and it helps my MPG's out ALOT
Click to expand...
At the risk of sounding stupid; How do Neon injectors help fuel economy and how involved/expensive is this modification?
 
Get a 4 banger DD and turn the XJ into a trail rig.

You're starting with a Jeep, which already ain't known for being good on gas. Then you're lifting it and putting big tires on it. This hobby ain't about how many MPGs you can get.
 
TKO'sXJ said:
At the risk of sounding stupid; How do Neon injectors help fuel economy and how involved/expensive is this modification?
Click to expand...
At the risk of sounding stupid myself, I have no idea. I know the Neon's injectors have a 4 hole spray opposed to the XJ's 1 I believe it is (someone correct me if I'm wrong) I just know that ALOT of people have done this mod and about 95% report better MPG's and a better throttle response
mcantar18c said:
Get a 4 banger DD and turn the XJ into a trail rig.

You're starting with a Jeep, which already ain't known for being good on gas. Then you're lifting it and putting big tires on it. This hobby ain't about how many MPGs you can get.
Click to expand...
touche
 
mcantar18c said:
Get a 4 banger DD and turn the XJ into a trail rig.

You're starting with a Jeep, which already ain't known for being good on gas. Then you're lifting it and putting big tires on it. This hobby ain't about how many MPGs you can get.
Click to expand...
that's what I did, bumped me up to 40mpg right away. Now the XJ only goes through about 6 tanks of gas a year :D
 
Really the only improvements you'd see in mileage would come from taking the lift off, going back down to the stock tire size, and taking anything with any weight out of it. And even then it would probably just bump you up to 15-18 mpg. You have a lifted, old 4x4. The mileage is what it is. The mods being discussed here might help a little but not enough to justify the purchase price.
 
Just for grins and giggles, read the JP Magazine article on mileage for the XJ, it was a three or four part article, and I believe the title was Mileage Master.

jpmagazine.com

Link to part I: http://www.jpmagazine.com/projectbuild/154_0808_building_a_fuel_efficient_jeep/index.html

And this is what the government says you SHOULD be getting: http://www.fueleconomy.gov/

A cold air intake should improve efficiency--not just a tube and cone filter, a real CAI kit. Good tuneup with quality components, your distributorless ignition is supposed to get NGK V-Fire plugs. Use synthetic lubricants in everything. As said, your biggest gain would be from YOUR driving habits, use the skinny pedal like there was an egg between it and the sole of your shoe. BE AWARE of what is ahead of you--anticipate light changes and take your foot off the skinny pedal and start slowing down without having to use the brakes--saves on brakes and fuel. Run your tires as full as you can without effecting tread wear, the harder the tire the less rolling resistance. I don't think lifts effect the MPG on an XJ as much as it might on more "aerodynamic" vehicles--face it, you can put lipstick on it but it is still just a box on wheels. A possible exception would be nose-high lifts. I like mine nose down about 1".
 
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Not to mention your speedometer is now off if you didnt reprogram it and if you are going by the odometer to calculate your mpg for every 90 miles it says you've gone then you've probably actually gone more like 100 - 105.
 
this is my beater, my other ride is a 2010 sierra 4door. im gettin about 19mpg with that truck, but id rather not put so many miles on it. and the lift is because im going to use it weekends for hollister hills(my backyard pretty much). i've never heard of the neon injectors, im going to look into that. and tb will probably be done when i do a true cold air intake/exhaust. i know this isnt the greatest vehicle to use as a commuter, but xjs have been my thing for awhile, and im not about to trade that out for a honda. and i have no space for another vehicle. and i was under the impression that keeping stock gears and putting bigger tires will boost mpg on the highway by dropping cruise rpms? i can see it hurting it during accelleration and city driving because of the weight, but this is mainly a highway cruiser.

joe-great article, thanks for the link. and my front end does sit about an inch lower than the rear, fairly new rubicon kit with stiff rear leafs.
 
redrider2911 said:
Not to mention your speedometer is now off if you didnt reprogram it and if you are going by the odometer to calculate your mpg for every 90 miles it says you've gone then you've probably actually gone more like 100 - 105.
Click to expand...

i compared my gps mph to my jeeps speedo and its only 2 mph off at 65-70. shouldnt affect it to much. i made sure the gps was accurate by putting it in my new truck. it was spot on.
 
moparmansfield said:
i was under the impression that keeping stock gears and putting bigger tires will boost mpg on the highway by dropping cruise rpms?
Click to expand...
Not true it was setup from the factory with a ratio that would give you the best all around performance any changes made to that will only lower your gas mileage. A complete lift setup includes a not just a lift and tires. If you want it drive like it did before the lift (same amount of power with the same cruising rpm and shift points) you'll have to do the gears too.
 
Add 4.10 gears + CAI + 62mm TB + 2.5" CatBack to what you already have and just try keeping your foot out of it!

If you can, you might just see about 3 more mpg... if you're lucky.

If you can't, you won't be doing much worse than you already are.


It would be cheaper though to drop 1.5" off your lift and reduce to 235/ATs... that would get you about 2 more mpg.
That's the way I've set up my current '95 DD. Plenty of power left and really only a small drop in mileage from stock.
I'll eventually do the other mods (except 4 gears) and fully expect to see 20-21 mpg hwy like 3 other XJs I've owned.
 
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After spending all this money on these mod's, for such little MPG gains, when is the break-even point?
 
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