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Post by 97neon06 » Sun Mar 11, 2007 8:22 pm

ok i my cat is shot on the inside rattling like crazy and causing my rpms to drop sometimes b/c its clogging up... not when i put my new catback exhaust on.. can i just hollow the cat out and would it give me a engine code??? and i was told that when i put my mp ecu in that it eliminates the lower o2 sensor or sumthin like that is it true and will it work??

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Post by fusion210 » Sun Mar 11, 2007 8:59 pm

You'll get a code.
Only the af/x pcm will eliminate the downstream o2.

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Post by 98moparR/T » Mon Mar 12, 2007 12:33 am

yea I say just get a new cat, maybe find one on here after somebody upgraded to a long tube

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Post by charger440neon2.0l » Mon Mar 12, 2007 12:49 am

I have the same issue. A mopar pcm will also not throw codes for catalytic efficiency. I am going to just delete my cat all together when I install my shorty header. No worries of emission testing where I live.

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Post by BlueR/T » Mon Mar 12, 2007 1:12 am


you will also have about a 50% decrease in mileage

the way to fix this is to just unplug the rear O2 sensor from its connector

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Post by infil » Mon Mar 12, 2007 10:59 pm

95 mopars are the only ones that do NOT read downstream o2.

as for what it will do, you'll slow the car down pulling a cat out on a shorty, even a mild longtube(kirk) will loose some power w/o a cat.

i averaged around .2 diff in the 1/4 mile, quicker with a cat, didn't gain time w/o one till i put my header in which moves enough air to put a massive cat on, however running a 2step and ignition cut for the top end limit, i'd be melting em down prety much every time i raced the car heh.
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Post by charger440neon2.0l » Tue Mar 13, 2007 1:29 am

I have a 95 that would give me catalyst efficiency codes all day long until I installed my mpp pcm then I no longer have a cel on for it. and no it did not mysteriously burn out the exact same time. My cats been rattling for a few years now and I've even had parts of ceramic come out my exhaust pipe. I've found them get wedged in my tips before. and even though I've not had a muffler and my cat has been gutting itself on my old engine I made 36 mpg in town and 40mpg at a cruise on the highway. I also notice about the same in town with my new engine, but its only been in for a week so I will have to see how it does.

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