better gas mileage

so i'm debating on whether getting a new DD or just buckin up and driving the XJ around. i've been filling up twice a week and its killing me! i've checked the tire pressure, just put a new pipe on, i'm probably gonna thro some new plugs in, and maybe even pull the front drive shaft... anyone else pull the front shaft for better mileage? did it even make a difference?

Not a noticable difference, remember all of the front internals are still rotating unless you have a disco.

I have no front axles and get same mileage.

yes, pulling the front shaft helps but not noticable enough for short trips. Over time, it adds up.

I'm not sure what size tires and gearing you have but after I regeared with 32s, it made a world of difference....30% improvement in gas mileage. Went from 12mpg avg to 16mpg.

check this out

i have a 98 with 35's and 4.56's

shimmy said:

so i'm debating on whether getting a new DD or just buckin up and driving the XJ around. i've been filling up twice a week and its killing me! i've checked the tire pressure, just put a new pipe on, i'm probably gonna thro some new plugs in, and maybe even pull the front drive shaft... anyone else pull the front shaft for better mileage? did it even make a difference?

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How much $$ will the new DD cost? Whatever the amount it would likely buy a lot of gas to run your XJ on well into the future. And keep in mind the new DD uses gas too so that further negates the savings. It almost never makes financial sense to replace one perfectly running vehicle with another just on the basis on fuel economy. For the numbers to work out the new DD would need to get 200% to 300% better fuel economy and fuel prices would likely have to be double their current rate, and even then it will take a while to come out ahead. You can't just look at as the cost of fuel, you have to view it as the total cost of transportation (that includes purchase price, maintenance, insurance, fuel, etc).

shimmy said:

i have a 98 with 35's and 4.56's

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You have the same setup I am running. First thing I can advise is get rid of all unnessescary weight (spare, tools, even skids). Secondly, pull your front shaft, I went with locking hubs from milemarker. Third, test different gas stations, I've found that I get the best mileage from Mobil 87 oct, might not be the cheapest in town, but I get the best mileage. And lastly, drive smart, no full throttle starts, keep your speed between 55-60 (rpm's 2100), for every day driving and 70-75 for highway (rpm 2500). Eventually, you'll find the sweet spot and keep in it.

Though your numbers may change, I have a few hop up's, bored tb, header, exhaust, intake......

I'm sorry, I'll just have to disagree with everyone who says "dude you should disconnect your shaft, it improves mileage." My experience is that when you do something to "improve your mileage" your driving habits change too. You adjust your driving to validate your choices and your decisions of what would give you better mileage.

The only thing to really improve my mileage has been terrain and altitude. I have had 3 xj's and the only signifigant difference I have seen in mileage came from either.

1. running entire tanks of gas on the highway in one stretch. My commute is 30 miles every day and I "thought" It should be considered highway, truth is that longer runs of 300 miles a stretch VASTLY improves mileage.

2. The gasoline in your area may not be ideal for your engine. I get better mileage in Texas than Louisiana and better mileage in Colorado than Louisiana.

3. New Oxygen sensor.

The previous have been true for 3 diffrent xj's. I am currently running NO AXLESHAFTS in my front end, that is a reduced rotating mass of a lot more than a simple driveshaft removal, and I am seeing NO GAINS! Why? Because I didn't do it to get better mileage, my driving habits didn't change a bit. Lo and behold, neither did my mileage.

Just take the XJ back to stock. I averaged about 21 +/- on the drive out to Moab (lots of grades to climb as well!) in my stock Chief.

I had a 98 ZJ that I removed the front axle shafts from and saw a mpg increase of about 2 mpg. BUT that was due to the fact that the front diff was shot and was creating a huge amount of drag. If the front end is in good shape then the difference in mpg's would be minimal. My XJ is a 2wd and it gets very comprabable mileage to all the 4wd's I know.

Two words: Honda Civic

j99xj said:

Two words: Honda Civic

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i say honda del sol. i had one that got 50 mpg and my friends hatch got like 30mpg

I still say you're better off overall by only having one vehicle vs two, regardless of mpg's. There's more to it than just mpg's when you look at the big picture. If you're looking to replace the XJ then I can see the logic, but getting a second vehicle on the premise of saving money will cost you more than you'll save. Just my $.02

For the number of miles you're driving at maybe 15 mpg (like myself)... perhaps 400/week, that's 20,000 / year. A little high, and perhaps a temporary spike in how much you drive. If not, that's about the mileage at which I would easily justify a second vehicle. You can find a car that has most of its value in a new set of tires that will also make the commute more comfortable.

I run 35's off road and put my 32's back on when just running up and down the hwy to work. I also have 4.56's. I get better milage and love the power going up and down the hills.

2001XJeep said:

I still say you're better off overall by only having one vehicle vs two, regardless of mpg's. There's more to it than just mpg's when you look at the big picture. If you're looking to replace the XJ then I can see the logic, but getting a second vehicle on the premise of saving money will cost you more than you'll save. Just my $.02

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That's some funky math you're using there brother...

Let's see. I spend ~$450.00 per month gassing up the XJ for my DD duties. I can buy a crappy old civic for about $500 that will reduce my monthly gas costs by about $300. So all I have to do is drive the Civic for two months and its saving me money. Even if I don't save that much each month, it will still pay for itself and keep on saving after a few months...

:dunno:

Don't for get insurance, taxes, tags, and maintenance costs on that honda.

Beej said:

That's some funky math you're using there brother...

Let's see. I spend ~$450.00 per month gassing up the XJ for my DD duties. I can buy a crappy old civic for about $500 that will reduce my monthly gas costs by about $300. So all I have to do is drive the Civic for two months and its saving me money. Even if I don't save that much each month, it will still pay for itself and keep on saving after a few months...

:dunno:

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Not quite, in your original post you said a "new DD". Crazy me, but I took that to mean you actually meant a new, or at least, much newer car to act as your daily driver. You never said you were talking about picking up a $500.00 turd w/wheels. Of course that changes the equation entirely and it would quickly save you some $$$ doing it that way.

2001XJeep said:

Not quite, in your original post you said a "new DD". Crazy me, but I took that to mean you actually meant a new, or at least, much newer car to act as your daily driver. You never said you were talking about picking up a $500.00 turd w/wheels. Of course that changes the equation entirely and it would quickly save you some $$$ doing it that way.

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The post of mine that you are quoting above says NOTHING that relates to this most recent post. I was refuting what you said because it did not make sense. I stand by that...

GSequoia said:

Just take the XJ back to stock. I averaged about 21 +/- on the drive out to Moab (lots of grades to climb as well!) in my stock Chief.

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When I was running 3.07s with 31s (I have 3.55s now), never putting it in 5th gear, I averaged about 21 as well on the highway, with the mileage from a few individual tanks of gas approaching 22mpg.

My mileage actually dropped when I swapped in the 3.55 axles, I think because I was driving it harder. Then I put on a header and started driving like a grandma again and am averaging almost 19mpg around town. All that with a 4.0 that's close to death too.

Beej said:

The post of mine that you are quoting above says NOTHING that relates to this most recent post. I was refuting what you said because it did not make sense. I stand by that...

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Stand by what you want, I don't really give a damn. You're wrong either way.