00lkwdXJ

i have a 2000 cherokee with three cats my buddy also has a 2000 but he has the one catalytic converter (mine is setup for california emissions) i would like to know if i can just delete the two under the hood and leave just the one or will my upstream and downstream o2 sensors flip out?

slk88cherokee

Dont mess with emissions stuff. Its federal law to have em and modifying is illegal. Its been covered a lot and its in the forum rules to not post emissions mods on a DD. Sorry not trying to sound like a jerk at all. If theres any sensors after any of the cats it will throw a CEL if they are removed or modded.

dukie564

three cats? never heard of that one.

If you don't live in CA, one CAT (49 state legal) is fine

dukie564

Federal law requires that you have one working CAT. I've never heard of having more than one, but the engine was designed to operate with one CAT, with an upstream o2 sensor before the CAT for a/f ratio measurements, and a downstream o2 sensor after the cat (for OBD-II) to adjust emissions.

As long as he has a working catalytic converter, he is fine, and will not throw any CEL codes. He's not talking about modifying or removing the standard emissions system.

00jeepXJ

My 00 has three... two in the manifold and one downstream. It's a California Emissions vehicle... If you try to remove them it will throw a CEL. Besides, tampering with a vehicles emissions is against the law and can get you into trouble if they ever do a in depth check.

slk88cherokee

Cool, I stand corrected then. I thought if it came with 1-2-13 or 2 that was how it had to be. Sorry for the mis information on my part.

00jeepXJ

I live to learn....that is why I am on this forum so that i can learn from others. I first noticed that I had two on my manifold the hard way.... still afraid to stick hand down into that side of engine to work on things. I have been looking for someone who sells a higher flow manifold cat assembly and have yet to find anyone. saving up my money so that I can buy a better exhaust for mine to open it up a little so it can breath better.

dukie564

i fail to see how removing the mainfold cats would throw a CEL....they didn't redesign the computer system just because California wanted to be **** about their smog tests. The two in the manifold are likely scrubbers, and would not make affect the engine operation if removed. Non-Carb equipped XJs run just fine with one CAT.

5150mechanic

It would prob thow cat effiecency codes, you could do what ever you wanted if it was to turn into off pavement only and not worry about getting raided by the cat converter police, wow.

x91j

As long as there is no o2 sensor in the cats you are removing it will not throw a code because there is nothing connecting it to the computer.

TheGreatGazoo

A 2000 cherokee will have a OBD II computer like most 1996 and up cars. that cpu has the abiality to have multiple O2 sensors if programed by the manufacturer. therefor if you have 3 cats yes it can throw a cel light if you remove the cats and install 1. now being that said IF there is not a O2 sensor after the LAST 2 cats it should not throw a CEL since there is nothing to detect the exhaust gas. but if there IS a sensor or 2 after the cats you CANNOT remove them it will throw a cel light.
here is an example i own a 2003 civic hybrid as my commuter car that i bought used in Mass. it has 3 cats and a O2 sensor after each cat, it is a cali emmissions car and has a PZEV sticker on the windows. my partener at work has the same 2003 civic hybrid that he bought from a dealer is PA where he has his vacation home is. he has only 2 cats with a sticker on his back driver side window that says NZEV. 2 exact same cars, same year, same color, same motor, different emmissions go figure. so it goes to show you the ECM can be programmed for different emmissions. so to change anything in your emmissions can trigger a CEL light.
now disclaimer for the feds.
IT IS against federal law to tamper with federal emmissions so don't do it

dukie564

mmmm i can't wait till Cali breaks off and falls into the ocean...

winston427

Removal of any part of the emissions system is against federal law. It does not matter what each state law is, federal law trumps it. It is also against forum rules to even discuss the removal of any part of this system. Read the rules people.

dukie564

it is against federal law to remove the system or to modify it so that it no longer cleans the emissions. I believe the OP was intending on trying to convert his Cali CARB equipped XJ to a normal 49-state 1 cat emission system, not remove it entirely.

edit: just checked - this may only be legal if the CAT is no longer functioning properly, and therefore needs to be replaced to satisfy EPA/Emissions requirements. So OP you might want to forget about this

gpXJ

It has 5 o2 sensors...one before each manifold cat, one after once they go down to single pipe, then one before and after the big cat out back. It's a POS design, and my Washington DC XJ has the same setup. Hate it.