Join Date: Oct 2001
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Re: YJ 4 banger gettin 13 miles to the gallon?
I'm running a I4 in my 4wd Ranger. It's a five speed, and I'm running 235s instead of the 215s that came on it. When it was new I was getting 25 or so on the highway. Now with 80,000 on it, I'm pulling about 20 or so on the highway (my speedo is calibrated correctly). Part of my problem is that I have a canopy on the truck with a big ol canoe rack on it. The rest, I'm not sure. I recently went to a K&N to help out some.
In your case though a couple of things to consider:
1. I believe even brand new 4cyl YJs were rated at something like 20 mpg on the highway.
a. Are we talking highway mileage?
b. Are we talking around town mileage?
2. Auto trannys usually get 2-3 mpg less than sticks.
3. Have you checked the following:
a. Air Filter.
b. Fuel Filter.
c. plugs/plug wires
4. As mentioned your larger than stock tires have the following properties:
a. They are a larger diameter so your speedo and odometer is off--you are travelling farther/faster than they show.
b. They are heavier so your engine is working harder.
A general tune up might be in order, as well as a good grease job. Check all the U-joints while you are at it....I once gained about 2 mpg by replacing a bad U-joint! Now granted, it was REALLY bad, but still!
Good luck, and let us know how you do!