Hey new to the xj world have a few questions

[Blackbetty98]

Hey guys new to the xj world :beer: I picked up 98 4.0 5speed xj. I have been driving it for a few months now. Last week I took the cat off (rattling) and put right I. It's place a thrush muffle. Now in my doing so I have no rear o2 sensor and ever since I put the muffler in the place of the cat I have noticed my mpg drop I can go throw 3/4 of a tank in about a day, my daily drive is about 70 miles round trip. I know that's ALOT of mile and I'm not going to get 20+ a mile but I know I should get more then what I'm getting.

I'm wanna know who is/has been in this same set up as me and what you did to help the problem out ??? I was thinking of o2 sims or drilling a hole on the outlet of the muffler and welding a bung to it, and putting 2 new o2 sensors in and seeing what happens. A lil more info there is no turn down or pipe to bring it out from under the jeep as of yet.. Any help is thankful..

[bigjim350]

Placeing a o2 sensor in the muffler will still throw a code, since it will still be reading "dirty" air. I would buy a new cat and put it on. You can get a cat with a o2 sensor bung for less than $100

[nickxj94]

Placeing a o2 sensor in the muffler will still throw a code, since it will still be reading "dirty" air. I would buy a new cat and put it on. You can get a cat with a o2 sensor bung for less than $100

Yeah X2 ^^^ the 97-01 needs the cat to regulate fuel mixture right and both or all four o2 sensors when equipped.

[XJ Wheeler]

Welcome to xjtalk, the portal to Jeep awesomenessessessess!

http://youtu.be/RsjA5DtfW2A

[Carves]

Guessing you have a CEL / MIL light, happening on the dash ??

Your year model needs two O2 sensors for the computer.

The rear (downstream) sensor needs a cat to provide comparison info against what the upstream sensor is "seeing".

Some general info in this link ... http://www.aa1car.com/library/o2sensor.htm

You might want to consider the upstream sensor as also needing replacement - given the mpg figures your experiencing.

[Paddletrucker]

I picked up a 5speed xj.

Hooray!!! Another 5 speed. THumbs up!! :thumbsup::thumbsup:




I'm not going to get 20+ a mile but I know I should get more then what I'm getting.


Are you sure??? My '95 5 Speed has 237,000 miles and it's bone stock. It gets 20mpg regularly. Usually more like high 20's into the low 21's just driving highway miles on my commute. When I drive it like I stole it, 19mpg.

I'm sure that'll go down after the lift, but 20 mpg's is doable with a stock 5 speed XJ.

The best I ever got was 24 on a long trip with all highway miles.

[Blackbetty98]

Thank you everyone for the info and the reply I will be gettinging a cat in the next couple of weeks then do a update on what kinda numbers I am getting thanks.