Any way to improve my fuel mileage on this Cherokee? I’m currently averaging 8 to 10 miles per gallon.

 

Need to know your tires, lift, stuff on roof, gearing, and highway vs city driving to get any idea how bad your mileage is. My stock 2000 up country with 180 k miles gets 18 to 20.
With all that said about all you can do is make sure ignition and fuel system is working ( no misfires for whatever reason, upstream O2 sensors etc etc), brakes aren't dragging, and you aren't carrying a bunch of weight and stuff on the roof.
Tires are a huge factor and of course if the motor is shot(low compression - burnt valves etc
the list goes on......

 

Agreed... there are so many things that have to be factored in that can affect the mileage. We also can't forget driving style. I think that affects it more than all the others combined. If someone's heavy on the skinny...trying to Flintstone it everywhere... well.. your fuel eco is gonna suffer greatly. And our old XJ's are about as aerodynamic as a 2 story house...brick on wheels... so that shoots one foot off before you even start the race. lol.

I'm pretty light on it myself...and like you, I get 17ish usually in the city...and 20-23 on the highway. with slightly larger tires (235s) ....(loaded but not on the roof, inside only)

 

8-10 mpg is pretty bad. Even my lifted MJ running on 32s is getting 16-18. I'd probably start with the O2 sensors. Dash gauge showing the engine warming up properly?

 

15+ in the city on my stock 2000. As other's have said, you are either real heavy on the gas pedal, or have some underlying condition that you need to locate. When was the last time some simple maintenance was performed? Plugs? Air filter? O2 sensor? Tire pressure? Are you carrying a bunch of excess weight? The back of my jeep is loaded with a hundred pounds or so of crap and I'm still getting 15 or more in my all "off highway" driving.

 

You should have a check engine light if you're burning that much gas.

 

i never found out my issue with this terrible gas mileage either. last items i never replaced was a throttle position sensor, coolant temp sensor and exhaust manifold/cats. those are the only suspects i have left on mine as i replaced all the vacuum lines, thermostat, o2 sensors and a buncha little odds and ends like a broken vacuum hose to the evap canister. does your engine struggle a bit when going back to idle instead of drop like many other jeeps i driven do? mine rev hangs a smidge and ever since it did that my mpg DIPPED bout 120-150 miles on a tank of gas with mixed highway and city driving. maybe check your intake to see if its torqued properly as well.

 

Well I forgot to tell you that I am a mail
carrier. Lol constant start and stops.

Everything is brand-new, engine, transmission, all gear ratios front and rear, transfer case, Tire tires etc. trucks in pretty decent shape. Takes a while for it to warm up though and run smooth. I may have some leaking injectors. But out of the obvious I was just wondering if it was something more I could do to try to increase fuel mileage.

 

you rural or local/in the city?. rural atleast here someone had an older cherokee that got about 13 mpg and the city i serviced a cherokee before that was rhd and the guy said he got about 11 mpg so it isnt impossible with constantly stopping and going like that. the mail carrier trucks designed for it gets even worse lol.

hmm for improvements tho you wont find much... try taking some weight out if possible, isnt much there to take out but a spare tire is heavy lol. and i would say the biggest type of improvement for "cheap" you can do is smaller tires like a 205/70/15 or 215. whatever shortens the gear ratios will help but again youre basically nearly as best as you can get.

 

My modest lift and tire set up can net 18mpg on the open highway, but that drops when running in town to 13. Your problem may not trigger a Check engine code as your OBD detects sensor failer, but not poor performance: it well not detect a flat spot in the TPS for example. Assuming your air filter is clean, spark plugs, cap & rotor and wires are good, check for dangling wires grounding. Then open your shop manual and test your sensors: O2, idle solenoid, MAP and TPS. If they are good and your throttle body is clean, move to the injectors. Note that O2 sensors should be replaced per the Maintenace schedule in your manual.

 

My '00 does pretty crappy around town. About 13 MPG.
But that is to be expected cause the way I drive.
Short trips with frequent stops.
Now on the highway taking it easy on the skinny pedal sometimes I can do as good as just under 22 MPG.
Pretty much stock XJ with 4 hole injectors running 225 75 15 Copper Discovery HT's.

 

Well in that case, I would say disregard all the advice you have been given, and start shopping for a Prius. I can't think of anything that will improve a 4.0's MPG under nothing but stop and go conditions.