Hey Everybody-

I bought my XJ about a month ago now, have been getting really crappy gas mileage. I had a check engine light indicating I needed to replace the o2 sensor behind the cat, did that, no more check engine light, but still really bad gas mileage. It's a 2000 with 101,000 miles on it, super good condition, it runs a lot better than my 98 Grand Cherokee with the same engine, but I get around 20mpg in the grand, and I'm only getting 13-14 in the XJ. My muffler has definitely been on some rocks, the whole thing is kinda caved in probably to 2/3 of it's original thickness. Could this possibly be causing the bad mileage? It makes a kindof odd tone too, but again, the thing runs GREAT, so I'm not sure where to start! Thanks!

-00XJCO

 

a bad cat and muffler could mess up your mileage. but the xj's are not known to have the best mileage to begin with. replace you muffler. you could also replace all the other o2 sensors the intake filter run some injector cleaner. this might help but the xj is not as curvy as the grand so the mileage will never be as good.

 

You may have smashed it to the point where it restricts exhaust flow. That could hinder performance.

 

What do you mean by the XJ's are not as "curvy"?

 

not as aerodynamic

 

Gotcha, that shouldn't make much of a difference around town though. Is there any difference at all in the drivetrains other than the XJ's with auto trans (at least mine) doesn't have the option to turn off overdrive? I thought they were identical.

 

i get around 14 for city driving and 17 on highway with my 2000

 

So what's the reason for my XJ getting much less MPG than my grand? They are both 100% stock at this point and running the exact same size tires?