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OK Uncle, I need to improve mileage or sell the Jeep.

I would say you would gain some mpg if you let it rev above 2k. By trying to keep the rpm low you're bogging the motor some. Let it shift so that it feels like it's easy for the jeep to keep its speed. Its just like on a bike, you can spin your legs slowly in a high gear but once you hit a hill it gets really tiring like that, whereas if you downshift, you conserve your energy. Btw, I've got a 2000 with 4.5" lift, 31s and 3.55s. I've seen up to 18 mpg on backroads and am getting 16-17 mpg consistently. It doesn't see much highway time. Just be smooth on the gas.

EDIT: I've got Thule Load Bars and 2 bike trays on my roof as well.
 
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I've got the stock roof rack, unfortunately I use it and need it to stay. I did several tests last year and found the E10 gas was no benifit. I guess its time to use the Jeep for errands again to test mpg. Around town it is very easy to drive without going over 2000rpm, but I can verify that method. With my 4.10's and 32's 60mph is right at 2000 aprox. I havent used it for alot of highway lately exept for towing a boat. And no I do not count mileage while towing. Thanks for all the posts, I really was just wondering if I could squeeze 2-3 mpg by lowering and retiring.

Thanks, Angus
 
If you're really that worried about gas mileage and the costs associated with it, why in the devil did you lift it in the first place? Almost every XJ I've ever heard about, driven, seen driven, or talked to the owner of has seen a mileage decrease after mods such as lift, roof rack/cage, bigger tires, even with gears to match. It's an acceptable tradeoff for the fact that your Jeep now looks uber cool and is more capable off-road, which is why I assume you lifted it and put bigger tires on in the first place. The multi-point post earlier in this thread had a lot of good ideas for maximizing mileage, most of which I try to incorporate in my daily driving. I get about 13 mpg around town, 16 on the highway. It's not good, but if I wanted good mileage I'd buy a Honda or Kia.

So are you really contemplating selling your Jeep because it gets fair gas mileage? Or worse yet removing the lift and bigger tires? Just to gain a couple more mpg?

I don't get it.
 
fubar XJ said:
So are you really contemplating selling your Jeep because it gets fair gas mileage? Or worse yet removing the lift and bigger tires? Just to gain a couple more mpg?

I don't get it.
Click to expand...






X2 :banghead:
 
It's not like he went out and did this last week and now regrets it. He said he did it years ago over 100k miles ago. I don't think he cared so much about mileage then when gas was around $1.50/gallon. Now thats it's $4, perhaps more so. Did your criticism of his decision from 8 years ago yield him any benefit for his current situation? No?

I'm going to have to agree with others about the rpm issue. You're keeping them too low. An engine will provide the best mileage (negate rolling resistance and aero drag) when outputting at its peak torque band. If you study a 4.0 dyno chart (which will change with various bolt-on mods), you'll find that its around 2500 to 3k rpms. Accelerating slowly is one thing, but for one tank of gas, try using just the 3 on the shifter instead of OD. It will still lock the torque converter but will also give you higher rpms. It's worth a shot before you go abandoning your best friend.

P.S. I would also be interested in hearing how your calculate your mileage, just for sh*ts and giggles.
 
I hear what you're saying Deftwill, I wasn't trying to beat the guy up over it, just that I don't get it. If mileage is now a huge concern when it wasn't years ago when he did the mods, there are only a couple of real long-term solutions if mileage tips and tricks don't cut it for you:

Buy a high mpg commuter car to handle daily driving chores, keep the XJ for weekend off-road/fun use.

Buy a high mpg commuter car for all driving needs, sell the XJ.


For me, and I imagine most of us here, removing mods such as suspension lift, bigger tires, bumpers and racks, etc. just to gain mileage would be akin to cutting off an arm or stabbing myself in the face. I just couldn't minimize the capability of the rig I'd spent so much time modifying and taking off-road just to gain a couple more mpg at the pump. I'd feel like scum of the earth every time I climbed behind the wheel, knowing that I'd ruined my Jeep in that manner. It'd be like training a world-class sprinter for a few years, getting him near the top of his class, and then deciding one day to change course and begin a daily regimen of McDonald's and Marlboros, along with slitting his Achilles tendon just for shits and giggles.


But hey, it's his Jeep, he can do whatever he wants.
 
Ive got basically the same set-up and get 15-17 city/17-22 hwy!What plugs are you using?I also run Amsoil synthectic in everything.
 
gump said:
Well, I have a 90 with 4.0 and auto, running ~5.5" lift, 33's and fullwidths. Running 3.50 gearing, and drove it to Moab from northern Minnesota averaging 19 mpg (got as high as 23 in the mountains). For me the key was keeping it out of overdrive to keep the revs in the sweet spot of 2000-2500 rpm.
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X2

I run 32x9.50 TSL's, 3.55 gears, AW4, and 4.5" lift. I run 3rd on the highway, no OD unless going on level or down hill. Revs are 2000 to 2500 and I get 19 miles per gal.

Rob
 
I say your Jeep is geared for Kansas and not Utah.....my experience is, with hills to navigate daily, is that I got 3mpg better with 4:56 gears than I did with 4:10's in my 89 XJ, when I was running 32's. With 4:10's, the tranny was always hunting for a lower gear when in OD and was rarely cruising in the center of the 4.0's power range.

On my current 2000 XJ, I'm running an AW4, 4:88's and 285/75/16's (33x11.25) and drive it daily in mixed freeway/city traffic and I'm averaging 15 mpg, but I can get it up to a consistant 17, when driving freeway only. I'm due to replace my 02 sensors, as I have 115K on stock units.....I'm guessing. ( I bought the Jeep at 90K miles) PS, my speedo is dead on with my GPS.
 
okay just to make sure, the ONLY way to measure gas mileage, is fill up your tank, when you fill it chose a SPECIFIC pump at a SPECIFIC gas station and let the nozzle click ONCE while fueling, i.e. dont top it off, making sure the nozzle is in the tank all the way......... thenn restart the mile odometer thingie, then drive it till its about empty, dont assume you spend all 20 gallons, go back to the same station, same pump, fill it up to the first click with the nozzle in all the way, and then you have an EXACT reading of how many miles you drove and EXACTLY how much gas you spent driving those miles. dont forget to correct for your tire size using a proportion. (stock gears as per 26,27, or 28" tire... ive heard all three so im not sure exactly which one the speedo is calibrated to). Doing that i get 15-16 shifting at 2k or lower, keeping RPMs between 1000 and 1500..... When i tried yalls idea of shifting later so as to not bog the engine, i got 12mpgs....so fuc* that :D
 
I get 22-24MPG out of my stock cherokees with 31s.

So if you drop it back down and revert back a few steps to a stock XJ you can improve your mileage.

Probably not worth it though.
 
emr1101 said:
okay just to make sure, the ONLY way to measure gas mileage, is fill up your tank, when you fill it chose a SPECIFIC pump at a SPECIFIC gas station and let the nozzle click ONCE while fueling, i.e. dont top it off, making sure the nozzle is in the tank all the way......... thenn restart the mile odometer thingie, then drive it till its about empty, dont assume you spend all 20 gallons, go back to the same station, same pump, fill it up to the first click with the nozzle in all the way, and then you have an EXACT reading of how many miles you drove and EXACTLY how much gas you spent driving those miles. dont forget to correct for your tire size using a proportion. (stock gears as per 26,27, or 28" tire... ive heard all three so im not sure exactly which one the speedo is calibrated to). Doing that i get 15-16 shifting at 2k or lower, keeping RPMs between 1000 and 1500..... When i tried yalls idea of shifting later so as to not bog the engine, i got 12mpgs....so fuc* that :D
Click to expand...

Better make sure it's the EXACT same time of day, with the EXACT same temperature, and the EXACT same relative humidity, and the EXACT same barometric pressure, and the EXACT same phase of the moon, and the EXACT same radio station must be tuned on your stereo. Also make sure you are wearing the same SPECIFIC shoes everytime, with different shoes you'll put the pump in at a different angle.:lecture:

You'll never get an exact number when figuring mileage, just be happy with +/- a couple percent.
 
i get average of 350-360 miles to the tank,heres what i did,iridium plugs,low ohm wires,ebay jacobs ignition system,ebay triple threat electric fan kit,ebay pacesetter header, catback exhaust,all synthetic fluids,k&n and a can of seafoam every 6 months,half in the gas and 1 ounce in the intake for the top end decarb,stuff works wonders and tires aired to 40psi for street and that is the best i can get out of her,its not the best but compared to most other trucks out there she does pretty good.
 
also do a K&N or similar air filter, NOT INTAKE, and a flowmaster or similar muffler. This will give you 10%-20% better mileage
 
Dustin_Z said:
also do a K&N or similar air filter, NOT INTAKE, and a flowmaster or similar muffler. This will give you 10%-20% better mileage
Click to expand...
You are so "full of it"!
 
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