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Unread 08-02-2012, 10:10 AM   #1
DoctorTim
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1996 XJ Cherokee 
 
Join Date: Sep 2010
Location: Huntington Beach, CA
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4.0 sucks too much fuel, replaced a bunch of junk, no difference.

Rebuilt motor
New tps
New O2 sensor
New exhaust manifold
New fuel filter
Stock 355 gears
Fuel pump makes noise (constant high pitch)
31 tires (makes lots of noise)
Getting 11.5 mpg. A 10% adjustment for the gearing makes 12.6
Friend gets 14 with same setup.


Will get an 8.8 with 410 gears. Will thathelp?
New injectors?
New fuel pump?
New tires?
97+ intake?


What should i try?

Thanks

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Unread 08-02-2012, 10:42 AM   #2
1CleanTJ
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how are you calculating fuel useage ?

what are you running for tire pressure ?

a/t or m/t tread ?

your xj full of stuff ?

and lastly, dont expect much mileage out of a lifted jeep
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Unread 08-02-2012, 10:54 AM   #3
jeepkid03
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Depends a lot on your gas also. 10% ethanol around here kills my mpg.
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Unread 08-02-2012, 11:30 AM   #4
DoctorTim
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Quote:
Originally Posted by 1CleanTJ View Post
how are you calculating fuel useage ?

what are you running for tire pressure ?

a/t or m/t tread ?

your xj full of stuff ?

and lastly, dont expect much mileage out of a lifted jeep
I fill the tank till the nozzle clicks twice. Set the odo to 0. The do mileage/ gallons the tank takes at next fillup. Then add 10% to itself. M/t tires, really chunky. I got diff covers, roof rack w/spare on top, thats about it. Not much junk

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Originally Posted by jeepkid03 View Post
Depends a lot on your gas also. 10% ethanol around here kills my mpg.
I use reg 87 fuel from costco
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Unread 08-02-2012, 11:31 AM   #5
DoctorTim
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Tire pres is at 35
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Unread 08-02-2012, 11:38 AM   #6
chriskeenan
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driving habits
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Unread 08-02-2012, 01:06 PM   #7
Millermagic
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Alignment. I went from about 10 to 15 by performing an alignment.

I also ruined a set of tires.

Obviously it's a poor way to perform measurement - but I would go from my place to my parents on half tank of gas ... now it takes a bit more than a quarter.
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Unread 08-02-2012, 02:05 PM   #8
bobthecatkiller
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Iv heard the spare on top hurts gas mileage
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Unread 08-02-2012, 04:30 PM   #9
DoctorTim
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i havent done a proper alignment in a while and my steering linkage is pretty old. i guess it should be time to do that after i replace it.

also i threw the spare in the back just yesterday so it may be a while before i can get a good average mpg without it on top.
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Unread 08-02-2012, 07:38 PM   #10
1CleanTJ
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i dont see you getting much more then 14-15 with mudders on.

removing the spare tire from the top should help

last time spark plugs were changed or gap checked ?


to be honest if your worried about milage, pick up a commuter car. I got a 93 honda civic for my daily driving. I drove my tj on 36's for years as a daily driver though, must of averaged about 12mpg on the highway my honda gets 37mpg on highway
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Unread 08-02-2012, 07:45 PM   #11
DoctorTim
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yeah replaced sparkers when i did the rebuild.

im going to get 33" A/Ts after i get the 8.8 underneath the jeep. the spare will one day find its way on a swing out carrier.
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Unread 08-10-2012, 06:33 AM   #12
xj_noob
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Try the good old seafoam treatment. And get a more free flowing exhaust. That's what i do, I just have the magnaflow catback exhaust and I seafoam every now and then and i get at least 18 mpg city and 22-23 highway.
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Unread 08-10-2012, 01:48 PM   #13
Azzy
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Quote:
Originally Posted by xj_noob View Post
Try the good old seafoam treatment. And get a more free flowing exhaust. That's what i do, I just have the magnaflow catback exhaust and I seafoam every now and then and i get at least 18 mpg city and 22-23 highway.
Seafoam doesnt do squat. Other than waste money, overheat your cat, and annoy the neighborhood.

If your injectors are dirty, swap them with newer ones. Might help.
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Unread 08-10-2012, 09:32 PM   #14
xj_noob
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Quote:
Originally Posted by Azzy

Seafoam doesnt do squat. Other than waste money, overheat your cat, and annoy the neighborhood.

If your injectors are dirty, swap them with newer ones. Might help.
It sure does help me out. :/ I just put it in my gas tank to clean my injectors and I get 320~ miles to the tank.
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Unread 08-10-2012, 10:04 PM   #15
DoctorTim
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Originally Posted by xj_noob View Post
It sure does help me out. :/ I just put it in my gas tank to clean my injectors and I get 320~ miles to the tank.
stock height and stock tires?
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