Removing a cat and why it's bad - JeepForum.com

 
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post #1 of 15 Old 09-12-2013, 05:59 AM Thread Starter
vadslram
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Removing a cat and why it's bad

Another thread here was asking about removing the catalytic convertor.
The legal impacts only apply for road licensed vehicles, pure trailer queens don't need them.
BUT
Unless you are ready to completely rework the engine management system (the computer) and the exhaust system, removing the catalyic will have a serious detrimental effect on you engine and performance.

What would happen?
Without the catalytic the second O2 sensor would always have false readings and keep trying to lean out the fuel delivery. making the engine run bad and hot.
Without some of the beneficial back pressure that the cat gives you will have raw flame passing through the valves greatly shortening their life.

and lastly without the cat on the road you risk becoming a donater to the state. Every state I know of has some pretty serious fines for knowingly removing the catalytic convertor.

So what options do you have?
Replace with a new stock covertor and your rig will run as designed.
OR
If you have upped the intake volume so it breathes easier you can get a high flow cat that will process all the exhaust your angry squirrels can breathe out while still giving the O2 sensor the right mix and the law no reason to seek donations from you.

For 99% of DD rigs replace it with stock CC and it will do what you need. The only reason to replace it in the first place is if your engine was running bad or burning oil for some time and it clogged.

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post #2 of 15 Old 09-12-2013, 06:02 AM
bogleparsons
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But I only gots one O2 sensor...

If it's not supposed to move and does use duct tape.
If it's supposed to move and doesn't use WD40
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post #3 of 15 Old 09-12-2013, 06:07 AM
Gage56
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Ohh Snap



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post #4 of 15 Old 09-12-2013, 06:09 AM
grandboost98
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Quote:
Originally Posted by bogleparsons View Post
But I only gots one O2 sensor...
Same here.

Not that Im for not running a cat, my Jeep still has one, but in CT if your vehicle is 25+ years old they dont care if you run open headers But youre totally right in that the engine was designed to work with a cat and without that back pressure, bad things will happen over time

89 Wrangler-3.5" HD BDS lift,M.O.R.E HD 5/8" booms on 35" KM2s
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http://tiny.cc/BRASSBALLSOFFROAD
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post #5 of 15 Old 09-12-2013, 06:58 AM
fratis
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I've got over 100K miles without a cat. If not running a cat is destroying the engine it is doing so at a rate I can live with.

-insert meaningless out-of-place political diatribe-
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post #6 of 15 Old 09-12-2013, 07:01 AM
95YamJam
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No cat here. Runs better than it ever did with one. No smog stuff here either.

My build: http://www.jeepforum.com/forum/f22/95-yam-project-1527472/?highlight=
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post #7 of 15 Old 09-12-2013, 07:08 AM
superj
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the cat is a federally mandated deal. just because your state no longer does smog inspections on your vehicle, they are still required and you can be fined. we just had this thread about three or four weeks ago and someone found it in black and white.

cats don't hurt your performance, even with a carb. i have a cat on my 87. it helps mellow out the exhaust note

I don't feel like working on anything at this time so i sold my yj.
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post #8 of 15 Old 09-12-2013, 07:11 AM
Gage56
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Waite for it






I love threads like this

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post #9 of 15 Old 09-12-2013, 07:15 AM
Old4X
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Ibtl

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post #10 of 15 Old 09-12-2013, 07:15 AM
superj
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on a side note, the thread title is fun. we could go off topic with this.

how do think you remove this cat?


I don't feel like working on anything at this time so i sold my yj.
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post #11 of 15 Old 09-12-2013, 07:20 AM
Gage56
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OMG I Love Caturday


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post #12 of 15 Old 09-12-2013, 07:24 AM
jsawduste
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Sorry this is information you picked up off the internet and are now claiming it to be gospel.

OBD1 does not have a downstream O2 (91-95 ish)

Most but not all OBD2 (96 up to hmm not sure) DO have a downstream and it IS used for fuel management. However the ECM algorithms have plenty of capacity to over ride the lack of or falseness of the downstream O2 voltage signal.
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post #13 of 15 Old 09-12-2013, 07:25 AM
Gage56
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YES !!!!!!!!

[IMG]http://i18.photobucket.com/albums/b112/89coltgt/stand-back-****s-about-to-get-real_zps1ac3b0bb.jpg[/IMG]

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post #14 of 15 Old 09-12-2013, 07:44 AM
MotoPhotog
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So on 1991 and previous models, theres not an O2 sensor relaying info from catconverter?

YJ Fully Built 258 - 6" of lift - 1.5" Spacers -Teraflex SYE -Tatton driveshafts -35" MT/R
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post #15 of 15 Old 09-12-2013, 08:08 AM
Anticanman
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Removing a catalytic converter is illegal. Whether its yours or you're stealing it out of someone else car to recycle it.

Luck Favours The Prepared
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