Down goes my MPG????

I have a 96 with a RE 5.5 and 33 x terrains. I am wondering why my gas milage has dropped in the last month or so and im now hearing about the cold and winter gas that may be the reason but what else can i check or replace that may help. One thing you should know is that last year i removed my cat and replaced it with a straight pipe. this means i just took out the o2 sensor. Dumb question but would my MPG get alot better if i put it back, what about a hollow cat. or what can i do with the o2 harness to trick the comp into getting a good reading. i know im burning rich i can smell it.

On a 96, that o2 sensor you took out (the one after the converter) serves no purpose in controling your air/fuel mixture. It's only there to make sure the converter is doing its job.

My money is on the fact it's getting colder, and they're putting winter additives in the gas. I've noticed my MPG's have begun to dwindle a little bit as well.

The '96 and newer have two or more O2 sensors. On a '96, with two, the first one, on the header downtube is the one that manages the computer. The second one indicates whether the cat is effective. All of our vehicles are of an age where the lifespan of sensors such as these are in question. As to the smell, my '92 has a gutted cat, and you can smell the difference. It runs great, gets good MPG, not rich, but you can smell a definite difference in the exhaust, as the hydrocarbons are not being burnt off by the cat. If your vehicle has over 100K on it, you would be doing yourself a favor by looking at the front O2 sensor, and making sure you have the proper t-stat installed (made that mistake, too). But overall, my '92 gets better MPG than my '96- does the motor with 200K spin easier?

is the front and rear o2 sensor the same b/c the front is old and i hag got a new a new one for the rear but now i removed it. my wuestion is can i use the one i got for the cat and put it in the exaust manifold

No they are different.......

buy a bosch o2 sensor #15729, they are for before or after the cat on the 96 XJ

How long have you had the lift? Have you regeared to match the 33" tires?

All of a sudden I went from 16/21 mpg to 15 nomatter highway or not and started smelling gassy at the pipe...(mines an 89) it was the Oxygen Sensor had gone bad. Replaced it and bingo back in the 16/21 range. Just my $.02 worth. When the o2 sensor goes bad the ECU goes into a default rich mode to safely opperate at any altitude without running lean and blowing the motor...hence the crapy milage.