Hey guys, I know this has been hashed out about a million times before, but I wanted to see if anything had been agreed on as a way to get better mpg from our cherokees.

I have an 89 Cherokee limited. 136k miles, 5'' lift, 31's, 3.55's and a roof rack. I change the oil at regular intervals, and the tranny fluid was new when I got the jeep at 120k. Also have changed the front and rear diff fluid, and seafoamed the engine.

Right now I am getting 11mpg around town, and 13 highway. I see tons of reports of people getting 15-18mpg with the same lift/tires combo. Can you guys help me get closer to that?

 

Better gear ratio would probably be the best bet.
Assuming your 31"s are mud tires, swap to A/T tires.
Maybe injector upgrade.
New air filter.
Proper tire pressure.
Manual transmission.
Don't drive on highway with 5" lift.

 

Yeah, the gears made a big difference for me. Everything else said above will help as well.

 

Roof rack isn't helping on the hwy either. XJ has enough aerodynamics problems without it.

 

Clean Your IAT. It's rear of the TB on-top of the intake manifold. ..................

Remove the restriction between the air-box and the TB.........................

Install 4 hole 19# injectors. > https://www.cherokeeforum.com/f2/199...r-swap-163105/

Check, replace your 02 sensor. > https://www.cherokeeforum.com/f2/ren...ce-rms-133153/

Also remember if your tires are say, 5% larger, on your calculator go "+" ,5%, of the miles, then, divide by the gallons. Bigger wheels turn not as much and UNDER read your miles.

 

Everything DFlintstone said, including the thread link at the bottom of his post.

Other issue on our old Renix systems is vacuum leaks. Primary culprits are the lines running to the reservoir ball behind the front bumper. Pull the reservoir ball and the lines and mount the ball under the radiator overflow tank (I used zip-ties) and chop off all the crappy plastic lines that are likely cracked and leaking.