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what am i doing wrong?

M

mitsumotors

NAXJA Forum User
Location
Winnipeg
I recently purchased a 91 xj limited, 4.0 aw4. I put a Chryco 8.25 in the rear with a factory lsd and 4.56 gears, in the front i have a dana 30 with 4.56 gears as well. 4.5 inches of lift and 33" BFG M/T's. I figured that with this tire and gear combo i should get not too bad of mileage but i'm getting around 12-13mpg. any suggestions?
 
Try a really good tune-up. New wires, plugs, cap & rotor cleaned or replaced, clean the TB, fuel injector cleaner, oil change (use a Mobil-1 301 series filter for extra .5 quart capacity. Why not?) air filter etc.
You'd be surprised what a difference this could make.
I haven't got any personal experience, but I've heard great things about a product called Sea Foam that should de-gunk the engine and help it run more efficiently.
 
I'm getting 18 Mpg by adjusting my driving habits, and keeping up with maintenance. 4 Inches 235s and 3.55s.
 
How does it go with 4.56s and 33s from a stop? Take off like a raped ape?
 
nickPRO said:
12-13 highway?

i think that the main issue with this could be the weight! 33's and all! any bumpers etc?
Click to expand...

That and raising the brick higher into the wind. Lift and bigger tires aren't going to be made up with gears. :wave:
 
That might be part of your problem :D The temptation to take off harder in a heavy brick hits the mileage hard...
 
Here is a comparison.

My son has a 98 XJ auto with a 4.5 lift and 32x11.50 tires.
He gets 17mpg strickly highway.

I have a 98 XJ auto with a 3.5 lift and 31x10.50 tires.
I get 20mpg strickly highway.

Our driving habits are very similar.
 
98XJSport said:
That might be part of your problem :D The temptation to take off harder in a heavy brick hits the mileage hard...
Click to expand...

well, sometimes but I mostly drive very conservative to try to get the best mileage.

someone told me that because I got better flowing aftermarket exhuast but did nothing to the intake my mileage will suffer, is this true?
 
Just stroke it!
 
When is the last time you replaced your o2 sensor? That can make a major difference in mileage.
 
cal said:
When is the last time you replaced your o2 sensor? That can make a major difference in mileage.
Click to expand...
yesterday, I did the 02 sensor, plugs wires cap and rotor, which all looked to be in really rough shape! hopefully that will make a big difference.
 
Thats the one thing I see make the most difference, other than driving style.

In my XJ, driving style can flux the mileage from 15 to 22.
 
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