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Is catalytic converter necessary for 99 xj to run right?
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04-02-2008, 05:45 PM
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#1
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Registered User
Join Date: Mar 2008
Location: New Orleans
Posts: 8
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Is catalytic converter necessary for 99 xj to run right?
I have a 99 XJ 4x4 4.0L. Will the engine run right with no catalytic convertor? Also, will the absence of a CC affect the O2 sensors?
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04-02-2008, 06:03 PM
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#2
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Registered User
Join Date: Aug 2006
Location: MI
Posts: 1,564
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Yes it will run. The downstream O2 sensor will light the check engine light if you remove the cat.
__________________
1996xj
3" Rough Country Lift, 3in shackles, 3 RC shocks, 31" BFG ATs, 2 KCs, Lighted Roofrack, Soft 8s, TC drop, Custom oil leak deflector.
If only i could get a set of tires to last me 10,000Miles
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Originally Posted by toates89
i am just gunna drive around in 4lo on dry streets, and peel out
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Originally Posted by 4.0H.O.XJ
I once got a ticket for jerking while driving it. The cop wouldnt let me use his pen to sign the ticket.
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04-02-2008, 06:48 PM
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#3
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Registered User
Join Date: Mar 2008
Location: New Zealand
Posts: 62
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No worries
I should run sweet and actually give you a bit of extra power. Maybe on the verge of being noticable maybe even a bit of extra MPG. I havn't done it on a jeep but you should just be able to ground that sensor on the body somewhere. That will stop the check light.
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04-02-2008, 07:04 PM
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#4
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Registered User
Join Date: Mar 2007
Location: Where ever I can wheel
Posts: 272
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It is against Federal law to remove a catalytic converter.
You aid tree huggers in their fight about us contributing to environmental damage.
You might gain 1/2 MPG per tank of gas.
Be a smart Jeeper and keep the cat in and let my grand kids have good air to breath.
__________________
Full Specs
2K XJ - 6" lift w/ 34s
'98 XJ Laredo - Stock (and staying that way)
'71 M151
I'm a proud member of MyUniBody
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04-02-2008, 07:19 PM
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#5
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Registered User
Join Date: Oct 2006
Location: Johnson City, TN
Posts: 980
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I bought my 98 with no cat and the O2 sensor is cut but my light isn't on. Oh well haha. The cat just gets clogged and kills your jeep.
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04-02-2008, 07:26 PM
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#6
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Registered User
Join Date: Jul 2006
Location: Chattanooga, TN
Posts: 405
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Yes, it will run right, but that doesn't mean you should do it.
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04-02-2008, 08:14 PM
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#7
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Registered User
Join Date: Sep 2007
Location: wichita, KS
Posts: 370
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theres things you can buy to make it sound like you dont have a cat
but yes, plz don't do it for all our sake...
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04-02-2008, 08:17 PM
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#8
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Registered User
Join Date: Apr 2007
Location: Atlantic Canada
Posts: 600
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you know when i was young and stupid and childless I removed cats whenever i could. i didn't know the environment pays for it dearly. They way I look at it now is how would you feel if the air you breathe smelt like rotten farts and the water tasted like where those farts came from. Our kids ,kids will probably find out. I don't want to knowingly be the sh%$5 flinger. 
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04-02-2008, 08:28 PM
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#9
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Registered User
Join Date: Apr 2008
Location: 850 Florida
Posts: 9
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It will more than likely sound terrible too...especially if you have aftermarket exhaust.
Just get a high-flow cat.
Magna-Flow makes a good one.
Your exhaust only needs to flow as much air (cfm) as your engine combination is anyway. So unless you have forced induction or large displacement with a super good flowing head and other internal mods, you won't notice much of a difference in a high-flow cat versus no cat. Plus the high-flow ones are legal. You might see a couple horsepower by replacing the stock with a high flow...and maybe one more hp by no cat at all.
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04-02-2008, 08:31 PM
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#10
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Registered User
Join Date: Jul 2004
Location: Rhode Island
Posts: 3,511
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just keep the cat
/ thread
__________________
97 xj
44 front, detroit, alloyed
60 rear, detroit, 35 spline alloyed
35" beadlocked km2's
3" midarmed
more bells and whistles than you can shake a stick at
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04-02-2008, 08:32 PM
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#11
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Registered User
Join Date: Feb 2008
Location: Portage, IN
Posts: 447
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aCTUALLY IT WILL HURT UR FUEL MILEAGE AND THE XJ WILL RUN BADLY. THE O2 WILL LIGHT THE CHECK ENGINE LIGHT AND THE SYSTEM WILL NEVER GO INTO CLOSEED LOOP. wITHOUT CLOSED LOOP, YOULL BE RUNNING REALLY RICH EXHAUST. nOT TO MENTION WHEN THE COMPUTER THROWS A P0300 CODE (CATALYTIC CONVERTER INEFFICIENCY) IT WILL TRY TO COMPENSATE AND REALLY PLAY WITH UR AIR FUEL MIXTURE BADLY MAKING A ROUGH RUNNING XJ.
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04-02-2008, 08:35 PM
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#12
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Registered User
Join Date: Sep 2006
Location: Long Island, NY
Posts: 3,571
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Quote:
Originally Posted by XJKyle1389
aCTUALLY IT WILL HURT UR FUEL MILEAGE AND THE XJ WILL RUN BADLY. THE O2 WILL LIGHT THE CHECK ENGINE LIGHT AND THE SYSTEM WILL NEVER GO INTO CLOSEED LOOP. wITHOUT CLOSED LOOP, YOULL BE RUNNING REALLY RICH EXHAUST. nOT TO MENTION WHEN THE COMPUTER THROWS A P0300 CODE (CATALYTIC CONVERTER INEFFICIENCY) IT WILL TRY TO COMPENSATE AND REALLY PLAY WITH UR AIR FUEL MIXTURE BADLY MAKING A ROUGH RUNNING XJ.
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no it wont. you are wrong.
__________________
Factory Four Link
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04-02-2008, 08:37 PM
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#13
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Registered User
Join Date: Jul 2004
Location: Rhode Island
Posts: 3,511
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Quote:
Originally Posted by XJKyle1389
aCTUALLY IT WILL HURT UR FUEL MILEAGE AND THE XJ WILL RUN BADLY. THE O2 WILL LIGHT THE CHECK ENGINE LIGHT AND THE SYSTEM WILL NEVER GO INTO CLOSEED LOOP. wITHOUT CLOSED LOOP, YOULL BE RUNNING REALLY RICH EXHAUST. nOT TO MENTION WHEN THE COMPUTER THROWS A P0300 CODE (CATALYTIC CONVERTER INEFFICIENCY) IT WILL TRY TO COMPENSATE AND REALLY PLAY WITH UR AIR FUEL MIXTURE BADLY MAKING A ROUGH RUNNING XJ.
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thats for the primary 02
the after cat 02 will(should) set off a code and tell you to replace your cat convoytah
__________________
97 xj
44 front, detroit, alloyed
60 rear, detroit, 35 spline alloyed
35" beadlocked km2's
3" midarmed
more bells and whistles than you can shake a stick at
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04-02-2008, 08:52 PM
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#14
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Registered User
Join Date: Aug 2006
Location: MI
Posts: 1,564
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The are some ppl that shouldnt be giving advice....
__________________
1996xj
3" Rough Country Lift, 3in shackles, 3 RC shocks, 31" BFG ATs, 2 KCs, Lighted Roofrack, Soft 8s, TC drop, Custom oil leak deflector.
If only i could get a set of tires to last me 10,000Miles
Quote:
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Originally Posted by toates89
i am just gunna drive around in 4lo on dry streets, and peel out
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Quote:
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Originally Posted by 4.0H.O.XJ
I once got a ticket for jerking while driving it. The cop wouldnt let me use his pen to sign the ticket.
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04-03-2008, 02:03 AM
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#15
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Registered User
Join Date: Mar 2008
Location: Albuquerque
Posts: 409
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I concure. If youre not absolutely possitive then tell us it is just a guess. We dont need to lead people into doing things that may hurt them or their jeep in the long run. Oh by the way I beleive the computer on the 99 is complex enough that even if a cat didnt have an O2 sensor in it the upstream O2 sensors may notice a difference and cause the jeep to get squirley. I dont beleive that there is much to gain by removing it and possibly much more to lose. So the safe bet would be leave it or get a high flow cat.
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