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Removing Cat & O2 Sensor

green50gt

NAXJA Forum User
Location
Goshen, IN
Ok, so I put in a 2 chamber flowmaster in my 98 XJ. Its not loud enough, so I was thinking of axing the cat. Normally I'd just do it, and be done, except the O2 Sensor is right in the middle of the cat. Is it going to run correctly if I remove the O2 sensor all together? I fully assume its gonna throw a code on the dash, which I am ok with, However I am just concerned that it will not run correctly. I have not had the opportunity yet to just unplug it to see what happens.

Let me know,

D
 
The O2 senson that you are referring to does not control engine operation. The first O2 sensor does that. But, if you remove or gut the cat, the second sensor will throw a code, because it's purpose is to see that the cat is doing it's job. And depending on your state's emmissions inspection, you may not get it to pass. Because your vehicle is OBDII, your check engine light must operate (look at the sequence of dash lights when you start), but obviously not stay on.
 
heyhar said:
The O2 senson that you are referring to does not control engine operation. The first O2 sensor does that. But, if you remove or gut the cat, the second sensor will throw a code, because it's purpose is to see that the cat is doing it's job. And depending on your state's emmissions inspection, you may not get it to pass. Because your vehicle is OBDII, your check engine light must operate (look at the sequence of dash lights when you start), but obviously not stay on.


Why not eliminate the Flowmaster and keep the catalyst?
 
Another choice option that seems to have really caught on in the ricer circuit is the addition of a "Cherry Bomb" muffler. Word has it they bolt on another 15-20 RWHP (but only on front wheel drives cars, so maybe more for our) and the good looks and sweet purrrrrr will defintely turn heads where ever you go.

I have the same setup as you, and had thought of removing the O2 sensor, from what I have heard your gonna have to deal with the Check Engine light being on all the time, or disabling it (the light only so you can still check codes obviously) If you go through with this post your findings please as I would like to know how it works out.
 
Do not get rid of the cat on the 98. It will make it sound so rice-a-roni-riffic that you will hate it. Believe me been there done that mistake.--------------------Kyle
 
removing the cat will not make it sound ricer if you have a muffler on it. also who ever told you putting a cherry bomb on anything will give you 15-20 Rear Wheel HP is a fucking moron and should be shot, and you just said it gives 20 Rear Wheel horse to front wheel drive cars, so your not too far behind
 
I have a '92, and about four years ago, I took off the cat, and 'cleaned it out'. I can get away with this because where I live, they don't check tailpipe emissions. I put the hollow cat body back on, and behind it I have the 'less-noisy' of the two noisiest Flowmasters. I can't remember if it's a 40 or 50 series. It sounds good- borderline annoying. I did the 'cherrybomb' before, and it sounded silly. You need a V8 with duals for that! And the Flowmaster should outlive the car.
 
that 2nd link is super over kill, the down stream O2 sends out a steady signal between .1 and .9v all you need to do is send a .5v (or so) signal back to the conputer
 
heyhar said:
I have a '92, and about four years ago, I took off the cat, and 'cleaned it out'. I can get away with this because where I live, they don't check tailpipe emissions.


Thank you for dirtying our air.

CRASH
 
Tealcherokee--------------On this particular model 97+ model removing the cat will make it sound ricer. Trust me. On the older models it isn't bad at all however. Makes it sound good. Oh and to answer crash on the dirtying air. Without the cat the emissions has said that the jeep is running just as clean as before with the cat. -----------------Kyle
 
I appreciate everyone's help, I am going to procede however by unplugging the O2 sensor and seeing how things go. My buddy has a 4.0 with NO cat, a 2 chamber flow, and 2.5" exhaust, and it sounds fantastic.

I don't mind throwing any codes, or the check engine light being on.

Thanks, Derek
 
offroadman83 said:
Tealcherokee--------------On this particular model 97+ model removing the cat will make it sound ricer. Trust me. On the older models it isn't bad at all however. Makes it sound good. Oh and to answer crash on the dirtying air. Without the cat the emissions has said that the jeep is running just as clean as before with the cat. -----------------Kyle


Wow, that is revolutionary! Someone should have told DC that they did not need to install a $500 part to meet emissions!

I bet they'll feel really dumb for making such a boneheaded miscalculation!
 
i have a 95 with no cat and some random muffler and at idle it has a really nice rumble but higher up in the rpms it has a ricer humm to it, atlest inside the jeep. i plan on switching to a 40 or 50 flow soon!
 
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