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removing the two catalysts converters under the JK

 
Old 09-19-2009, 04:28 AM
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Default removing the two catalysts converters under the JK

hello eveybody

what about removing the two catalysts converters under the JK, and replacing them with a properly built pipe with a same diameter of the rest of the exhaust ?

I think the engine will breath more easily , but m not sure if the superchip can work with it ?
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Old 09-19-2009, 04:41 AM
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Modifying the y pipe suggests the need to gain control of A/F mixtures with a wideband O2 controller. Not sure that this is going to play well with the SC Flashpaq and it isn't something that can be accomplished without a fair amount of tuning knowledge.
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Old 09-19-2009, 07:39 AM
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thnks guys for your replies

a friend of mine replaced just the two converters that m talking about in his 07 Jk , he felt that the engine breathe and performe better , specially in the speed between 80 km/hr to 140 km/hr

Its also gaved him a nice deep sound from 0 to 80km/hr then its disappear

it costs about 80$ to do it

I wonder how the performance and sound would be if all the converters were taken off


I want to try taking off just the two convertrs , but m hesitated because i have the SC flashpaq installed in my jk, and i dunno if the SC flashpaq support it
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Old 09-19-2009, 09:37 AM
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The two upstream are cats, the two downstream are resonators only. I had to remove one when I installed my RK long arm lift. Flashpaq works fine, nice low rumble. May do the other one also, one day.
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Old 09-19-2009, 09:53 AM
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Originally Posted by Phishjeep View Post
The two upstream are cats, the two downstream are resonators only. I had to remove one when I installed my RK long arm lift. Flashpaq works fine, nice low rumble. May do the other one also, one day.
That's good information! I was not aware that two of these were resonators and assumed that all four were cats. What does the interior of the resonator look like?
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Old 09-19-2009, 01:38 PM
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Is that true?
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Old 09-19-2009, 02:18 PM
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Originally Posted by Phishjeep View Post
The two upstream are cats, the two downstream are resonators only. I had to remove one when I installed my RK long arm lift. Flashpaq works fine, nice low rumble. May do the other one also, one day.
How certain of this are you? This would open up a whole new page. Four you could not get by with removing...but two and I believe o2 sensor simulators would work.
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Old 09-19-2009, 02:46 PM
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Default removing the two catalysts converters under the JK

any pics of those catalysts??? which are which?

Would removing those activate the check engine warning? due to O2 sensor been inside the catalyst?

would anyone write a proper write up for this, I have been thinking about removing it since i got the jeep.
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Old 09-19-2009, 04:11 PM
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Here's a diagram of our cats.



From what I see it looks like the second two are just resonators. The first o2 sensors(before the cats) dictate A/F ratio. The second o2 sensors(after cats) just monitor emissions.

So putting test pipes in way of the resonators won't be a problem at all. I'd want to hear the sound though. Resonators often take the raspiness out of exhaust notes. I've had friends take resonators out of stock exhausts before and it's sounded like ass.

To jump on what Redneck was saying about actually replacing the cats with test pipes is easier said then done. A o2 simulator could easily be used on the "after cat sensors" to "trick" the OBDII system into thinking the cats are still there.

My question would to worry about how much removing the cats would "lean" out the A/F when in Open Loop.
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Last edited by drumnatural; 09-19-2009 at 04:16 PM.
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Old 09-19-2009, 04:56 PM
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Just keep in mind that the engine exhaust system is tuned based on length and back pressure which the catalytic converters contribute to significantly. As with any "system" improving/changing/eliminating one component can cause undesirable side effects.

There probably is a programmer that includes a program for off-road only tuning like removing the cats.
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