What's up guys. Just wanted to see if there was anything else I can to increase mpg? I'm driving a 93 XJ w 100k miles and with a 4.5" lift and 31s on steelies. Already changed my plugs and wires, cap, O2 sensor, flow master muffler and cat, new hoses, oil change every 2k miles, even use flue additative. Getting 10.9 MPG average. Thanks

 

You could get a Honda civic. But seriously. I get about the same. You could change your driving habits, take tire off the roof, proper air pressure in your tires, make sure your air filter is clean, make sure your o2 sensors and exhaust system is working properly

 

Sorry. Missed the part that said you replaced all that stuff already

 

Re gear it,Driving habits and don't carry around 200lbs of extra weight you do not need.

 

You didn't list a speedo gear change, that will account for lower mileage readings. I am 10% off with just 30's. Stock tire size on door label is ridiculously small.

http://go.jeep-xj.info/HowtoSpeedoGears.htm

 

I swapped the diff fluid in my '00, Dana 30 and Chrysler 8.25 3.55's, for synthetic. VV975 for me. Open rear and do not tow. Check this out. Might give you an idea or two.

http://www.jeepforum.com/forum/f11/m...5-ats-1551782/

 

Change your air filter if you haven't already.

 

Woof! Ease-up on the oil changes. Even 3k mile OCI's tend to be overkill these days. You're only wasting money and oil. I do 5k mile OCI's and know based on the UOA's I used to do that I could probably go to 7k or more, but multiples of 5 are easy to recognize on the odo and don't risk me accidentally pushing my oil too far.

Honestly, 11 mpg average for a 4" lift and bigger tires sounds pretty typical to me especially if you didn't regear and doubly especially if you either didn't change your speedo gear or compensate mathematically in your MPG calculations for the bigger tires.

The best thing you can do at this point is slow down. I know most people don't want to hear that, but drag increases EXPONENTIALLY with speed, and when you start getting into 60-70 mph territory with the terrifying drag coefficent of a lifted XJ, drag really starts to pile up.

 

As for weight, reducing rotational mass will help the most. Replace steel wheels with alloy. Replace heavy MT tires with an AT (except BFG) or HT tire.

 

You could increase your base timing with the CPS mod. I think that's silverxj's mod. I did it on my 95 which seemed to make 70mph cruising easier, which I have no data to back up. It didn't change my mpg at all which I do have data to back up.

The next step would be increasing the compression ratio.

 

I figured my MPG would go down with the lift and tires. (Which are AT) but it was just about the same before I lifted it. I have a cold air intake as well. I've done slllst everything you guys have mentioned except regear. I figured I'd get worse mpg with the lift and tires, just wanted to see if I could boost my MPG a bit. I definitely don't drive it like I stole it either, I drive like an old man 😂

 

 

When was the last time the tranny fluid was changed? You could consider new fuel injectors as some claim that helps slightly. Another option could be an electric fan.

 

Tranny fluid about 5k miles ago. I'm just getting bored and wanna make the jeep as economic as possible. New fan is actually a good idea. 👍👍👍👍 ty for that

 

Aerodynamics are unheard of on Jeep forums, but is a definite factor worth looking into.

The suspension of the Jeep is a fantastic parachute when driving, and can easily be fixed. A stock Cherokee front skid plate is very beneficial to reducing drag, while also adding protection.

Also belly skid plates help a small amount as well depending how flat and large they are.

Removing the stock roof rack bars, and extra weight as others have said also helps.

This is the easiest way to make the Jeep more aerodynamic without going too crazy