It will more than likely throw a code since the sensor won't be seeing a "cleaned up" exhaust.

 

It might make it run rich and give you more power that way.:thumb::teehee:

 

I've seen a couple options to do this. A simulator or a shadetree trick that usually works. You get gasketed spark plug non-foulers, drill one so the o2 fits thru and screw the other one over it then put it in. (They normally come in 2 packs)

I had #2 ready when I gutted my cat (Rattling bastard) but never needed to. It never threw a code for it.

 

Jeff- I may need a call with tips on gutting a "rattling basterd" :sonicjay:

It's for the wife's ride.:thumb:

 

Look up MIL SIM on the googles. There you will find how to make a simulated o2 sensor so you wont trip the CEL.

The rear o2 does nothing for Air/Fuel ratio, its only there to monitor the cat. So leave the up-stream o2 alone and you should be fine.

On that note, there is no reason to remove the Cat. Keeps the air clean and they really dont rob that much power. If your only goal is more power then you need to look into real power add on's not removing emissions equipment.

 

buzzkill.....

 

I did this on my TJ and I hate it. I welded in the spacer to trick the O2 sensor. I am running a high flow muffler and no cat and plan to change it back as soon as I get time. I cannot stand the torque I lost by getting rid of the cat.

I know, it's not an XJ, but food for thought.

 

A little backpressure is good.

 

I ran no muffler with just a cat, no problems, then the cat started rattling and drove me nuts, so I cut the tail pipe off, took a screwdriver and broke up the rattling peices of cat and threw them out, ordered a muffler, installed it, with an empty cat and had no problems.

never once after emptying the cat did I through an engine code, nor did I notice it adding any power, or losing any power.

Muffler was a flowmaster 40 series.

If there is nothing wrong with the cat I wouldnt mess with it.

 

You didn't notice any loss of torque?

 

Im not trying to gain power its just extremly annoying and purchasing a cat isnt really what I wanna do.

 

O2 sim

You can make your own O2 simulator for about $2.00

 

And doing that will stop it from throwing a CEL code?

 

yep

 

i have an 04 wrangler, jeep was throwing a code that the cat or whatever was bad so I pulled it off and noticed it was falling apart inside. I just gutted it and installed it all back together. sounds better, didn't notice any difference in performance.

as far as the light on the dash I just leave it and deal with it.

 

I have a 1998 XJ with no cat. I just left the O2 sensor wires dangling under the jeep, for all I know they have been ripped away long ago. The cat was replaced with a strait pipe and I have a cheap thrush muffler on it. it still runs the same.
Check Engine light has been on since I bought the jeep.

 

 

I took a straight pipe filled it with steel wool dont pack it to tight. I kept the s/w in by cutting a slot in the pipe to accept flat stock 1/4in thick and half the diameter of the pipe .


Flat stock----------\/
----------------------/--
(((((Steel wool))))
-/-----------------------
/\---Flat stock

 

thank god for OBDI

i scrapped the cat that was on my jeep and it was like getting 25% off the purchace price.