Hey guys, I have some questions about my 2000 grand cherokee Laredo.
First of all, I’m at 357,000 km on the odometer, which is probably the start of the issue.
I did some calculating on my mileage on the way to work, and I’m getting about 12 miles a gallon if I did my math correctly…. Which I just figured out properly! Sorry about that!
I was scrolling around on the forums here, and seen some people saying that the 02 sensors may be getting worn out or are completely screwed causing me to run rich?
also possibly my injectors or fuel filter might be pretty gunked up? Could use some info from all of you jeep wizards out there? Just to get the best idea of what way I should go about fixing the issue without bankrupting myself in the process?
It runs fantastic, never fails to start, 4x4 works great, but it’s just a pig on fuel.

If you haven't changed your O2 sensors in a long time, 100K or more then yes you probably have worn out sensors. Like solar panels, they generate electrons (voltage) to tell the ECU how long to pulse your injectors. They do wear out eventually and will give a false reading on the presence of oxygen in the exhaust and cause it to be running rich. They are the most neglected tune up part and should be changed regularly

Okay so when I bought it, it backfired real bad, causing the muffler to eject itself from the CAT
and I got a new muffler installed, but not the CAT, I was thinking the CAT might be plugged up?
I’m also thinking about some new injectors because I don’t think those have been changed but I’m not sure.

If the cat is clogged up, the symptoms usually include no power and no higher rpms. A new cat wouldn't hurt, especially if you have to pass smog checks in your area

Okay well my cat should probably be replaced or removed then along with the 02 sensors and a new fuel filter it should run more efficiently! Thanks for the help! I’ll be back to let y’all’s know how it goes! And I’m in Alberta only need a CAT to pass inspection mines already been passed so I should be able to just cut her out!

Good luck

One question I also had, is can I put a TJ body on my frame?

You don't have a real frame. It is uniframe, all spot welded together

That’s no fun :/ oh well I suppose!

Wheel base on the XJ is too long for that anyway