FIrst off I know my jeep will never have great gas milage, it's a jeep it's gonna be bad. But Is there any way to improve it?? I have a 89 wrangler, with a obd2 4.0 out of a 96 Cherokee, ax15, stock transfer case and d44 rear and d30 front 3.73 gears that are soon to be 4.10 gears. It's on 36in super swampers with beadlock rims, I get roughly 120 miles to a tank and I have the 15 gallon tank so I'm getting about 8mpg. Does this seem about right? The 4.0 has a throttle body spacer, cold air intake and an aftermarket cam and no cat and a aftermarket muffler. Is there any way to improve it so I don't have to fill up every other day when I drive it would be great!
Well.... do a tune up. With what you are running tire wise, it seems kinda low. I would had guessed closer to a 10-12 mpg. A hard top will improve mileage a tad but keep in mind... you're basically pushing a billboard down the road.
Mine is a 4.0, AX15 and I'm running 33" with 4:10 and I'm averaging around 16.
tires are the killer.. also is your speedo corrected? get some AT's for the street in say a 33 and that would help some.. good tune up as above.... I pulled around 16mpg with 4.10's and 33's with my auto YJ.. my xj on 35's and very heavy pulls around 14mpg-15mpg...
do you have the down stream OS? with obd 2 you should have. what codes are you getting? with no cat you should be throwing a code and are running in limp mode.
It has the down stream o2 but didn't think it throwing a code because of that, i have a hard top and I don't have a speedo in the dash, I have a custom steel dash and just use a gps for speed and milage, I guess I'll just see how much the 4.10 gears help and mabe look for a second set of tires and rims.
Thanks!
My 91 4.0 gets around 16 which I think is great. But what do I know I am comparing it my f 350 with a 460 and our Suburban running a 350 with 4;10 gears
I have a 4.0 running 35's with 3.73 gears. I'm too tall gear wise for off-road, but on-road I'm getting about 16MPG. I'm turning 2000 rpm's at a tad over 70 mph, great for freeway cruising. It's a fine line between lugging or over-revving, with 4.10's you will accelerate faster but may be turning too high rpm's to get good mpg's. I think you need some engine work.
BTW unless you have a metal gas tank it's an easy fix to turn a 15 gal plastic into a 20 gallon tank.
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