Also a clogged catalytic converter can cause terrible gas mileage It would cause bad mileage but also the jeep would perform like a dog.

 

http://bit.ly/18CWrEV

Click on the first video.......

 

Way to be an ***. By your logic most of this forum is redundant.

 

When you checked codes what did you get ?

 

I haven't been able to. My XJ doesn't have anywhere to plug my scanner in. And from what I've read, its not too fun to use other methods.

 

What year are we talking about ?

 

94.

 

READ THIS....http://jeep-xj.info/HowtoECUcodes.htm

 

Okay awesome. Thanks for the info.

 

Yep you might get 12 and 55 disregard these.....

 

I got these. 12353355. Not sure how to read these. 33 is AC related. So 35 is my code?

 

Okay. None of those relate to fuel economy 35 is fan relay, but I have mine wired to a switch. So I guess I'm still at a dead end.

 

Not really remove battery cable for 15minutes or longer to clear codes then drive a few and recheck see what comes back. If you get same codes .You've eliminated any sensor being a issue. Then its back to basics last complete tune up was ? Then you've got possible fuel issues whith bad fuel pressure regulator,leaking fuel injectors.

 

Will do. What confused me is, the jeep is running great.

 

Mine was to then discovered fuel pressure regulator had a bad diaphragm .Was sucking fuel thru vacuum line to it causing bad mileage. Not saying that's your issue . Could be something different . Its a process of elimination.