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XJ Ask the Question Thread
CF Veteran
Joined: Sep 2010
Posts: 12,692
Likes: 6
From: Mercer County, NJ
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
And this is meant to be all CAPS. Im yelling
Moderator of Jeeps
Joined: Jul 2011
Posts: 21,029
Likes: 3
From: Frederick, MD from Cleveland, OH
Year: 1993 YJ Wrangler
Engine: 4.0 I6
Apparently the ring and pinion in my 8.25 are not aligned properly, therefore wearing incorrectly. Could that cause bad mpg? Getting like 10 mpg on 31's with steel rims and 3" lift
I know I should change plugs, wires, Cap and Rotor for now. Anything else I should be aware of?
I know I should change plugs, wires, Cap and Rotor for now. Anything else I should be aware of?
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
I don't remember which axle you mentioned but front axle buy two quarts, rear buy three. Fluid capacity charts all over the interwebs.
Doubtful. Lots of maintenance to be done regarding mileage... which transmission and gears do you have with your 31s, and how are you calculating mileage?
Year is very important to know. 1999 like in your profile?
Apparently the ring and pinion in my 8.25 are not aligned properly, therefore wearing incorrectly. Could that cause bad mpg? Getting like 10 mpg on 31's with steel rims and 3" lift
I know I should change plugs, wires, Cap and Rotor for now. Anything else I should be aware of?
I know I should change plugs, wires, Cap and Rotor for now. Anything else I should be aware of?
Year is very important to know. 1999 like in your profile?
Member
Joined: Jul 2010
Posts: 103
Likes: 0
From: Georgia
Year: 1988
Model: Cherokee
Engine: 4.0L HO from a 91 Comanche.
Not that, the stuff next to the firewall passenger side, three or so color coded plastic vacuum lines, blue, red, yellow, etc. One goes down to the t-case, one to some sort of selenoid down by the blower motor along with the black w/ red wire, I'm 90% that turns the light on in the cab PART TIME. I'm just going to reverse engineer it, shouldn't be too hard, and put in flexible line.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Not that, the stuff next to the firewall passenger side, three or so color coded plastic vacuum lines, blue, red, yellow, etc. One goes down to the t-case, one to some sort of selenoid down by the blower motor along with the black w/ red wire, I'm 90% that turns the light on in the cab PART TIME. I'm just going to reverse engineer it, shouldn't be too hard, and put in flexible line.
https://www.cherokeeforum.com/f51/fr...ss-91-a-38629/
Member
Joined: Jul 2010
Posts: 103
Likes: 0
From: Georgia
Year: 1988
Model: Cherokee
Engine: 4.0L HO from a 91 Comanche.
I just eliminate the vacuum source and all the lines and do this:
https://www.cherokeeforum.com/f51/fr...ss-91-a-38629/
https://www.cherokeeforum.com/f51/fr...ss-91-a-38629/
Anyone know what breaks when you throw to much at the axle?
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Oh that junk. Yes, get rid of the vacuum disco. In theory it affects mileage but nobody who's eliminated notices any difference. The factory stopped adding that unreliable crap partway through 1991 model year.
Why do you want 2.42:1 gears in there? Do you have a monster diesel or is everywhere downhill? 3.07:1 came stock for 4.0L gas and 2.5L diesel XJs with manual transmissions.
Why do you want 2.42:1 gears in there? Do you have a monster diesel or is everywhere downhill? 3.07:1 came stock for 4.0L gas and 2.5L diesel XJs with manual transmissions.
CF Veteran
Joined: Oct 2009
Posts: 2,867
Likes: 16
From: Fauquier County, Virginia
Year: 1991
Model: Cherokee
Engine: I-6 4.0 HO
Oh that junk. Yes, get rid of the vacuum disco. In theory it affects mileage but nobody who's eliminated notices any difference. The factory stopped adding that unreliable crap partway through 1991 model year.
Why do you want 2.42:1 gears in there? Do you have a monster diesel or is everywhere downhill? 3.07:1 came stock for 4.0L gas and 2.5L diesel XJs with manual transmissions.
Why do you want 2.42:1 gears in there? Do you have a monster diesel or is everywhere downhill? 3.07:1 came stock for 4.0L gas and 2.5L diesel XJs with manual transmissions.
Confirmed no mpg loss with the disco eliminated. My 91 was lucky enough to at least have a balanced driveshaft with the disco so no vibes. Its nice to be able to throw into 4x4 and go with no worries.
As far as 2.xx gears, Hell I have a 1.25 gears! Traded my 4.0 and trans for some bike pedals. I have solid 'buns an ties'! Gets me everywhere!
Member
Joined: Jul 2010
Posts: 103
Likes: 0
From: Georgia
Year: 1988
Model: Cherokee
Engine: 4.0L HO from a 91 Comanche.
Oh that junk. Yes, get rid of the vacuum disco. In theory it affects mileage but nobody who's eliminated notices any difference. The factory stopped adding that unreliable crap partway through 1991 model year.
Why do you want 2.42:1 gears in there? Do you have a monster diesel or is everywhere downhill? 3.07:1 came stock for 4.0L gas and 2.5L diesel XJs with manual transmissions.
Why do you want 2.42:1 gears in there? Do you have a monster diesel or is everywhere downhill? 3.07:1 came stock for 4.0L gas and 2.5L diesel XJs with manual transmissions.
CF Veteran
Joined: Oct 2009
Posts: 2,867
Likes: 16
From: Fauquier County, Virginia
Year: 1991
Model: Cherokee
Engine: I-6 4.0 HO
You boys are hilarious, do you not ever use lowrange? I want decent highway gears, no I don't have a diesel, I'm going to run 16-18 psi supercharged and I would like to get 25 mpg, I already have more torque than I'll ever use in 4 low, I'm bumping up to the '99 manifold and comp's most agressive cam. I don't think I need a 5.15 rearend like you 2.5L guys. I have a 3.55 rearend currently because I had the aw4, and I redline it at 35 mph in fifth in lowrange.
Edit: I'm going to expand on this post... why are you running in 4low at 35?
Moderator of Jeeps
Joined: Jul 2011
Posts: 21,029
Likes: 3
From: Frederick, MD from Cleveland, OH
Year: 1993 YJ Wrangler
Engine: 4.0 I6





