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Discussion Starter #1
What are the pros and cons of removing the cat? I have removed them off a 3.0v6 and a 3.4v6, mainly because at the time it was the thing to do. Here is SC we dont have to worry about emissions. I now have a 90 4x4 with a 22re 170k miles that runs like a top. I know it gets clogged and all but serves a purpose. Would you cut it or not? why?
 

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Im currious about the same thing.
My 1992 pickup 3.0 is missing the
Cat as well. And throwing a O2 code
Doesn't run quite right and thought
Maybe the cat being gone might have
Something to do with it.....



Sent from my DROIDX using Tapatalk 2
 

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Im currious about the same thing.
My 1992 pickup 3.0 is missing the
Cat as well. And throwing a O2 code
Doesn't run quite right and thought
Maybe the cat being gone might have
Something to do with it.....



Sent from my DROIDX using Tapatalk 2
From what I have recently learned, the cat is used to do nothing but reduce the amount of pollution your vehicle is putting out by burning te remaining oxygen left in the exhaust. Hence oxygen sensors before and after the cat. The engine makes adjustments to fuel trim based on the inputs from those two sensors. The first sensor tells how much O2 is stl present and the second checks the cats work. The ECU takes the info from those sensors and adjusts accordingly to perform as well as it can while meeting emission limits. If you have bad cat, the engine throws a code. Bad sensors fwd or aft, the engine throws a code. Off roaders and racers use hi-flow cats or no cats at all to get the best performance from their vehicles however, for the engine to Perform at the highest level the ECU must think that it's still doing its job correctly. So an O2 simulator is slapped on in leu (or in URD's case, in conjunction with) the downstream O2 sensor to let the ecu know all is fine and dandy. So, removing the cat can improve overall performance. The only caveat is that the downstream O2 sensor must be tricked into letting the ecu know that it is keeping within hippy- I mean federal emissions standards.
 

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Im currious about the same thing.
My 1992 pickup 3.0 is missing the
Cat as well. And throwing a O2 code
Doesn't run quite right and thought
Maybe the cat being gone might have
Something to do with it.....



Sent from my DROIDX using Tapatalk 2
Doubtful, the cat on my 3.4 clogged @ 325,XXX and I removed it. I sold it for a hundred bucks and built myself a new exhaust system with the funds. It runs fantastic, and I haven't noticed any drop or gain in mileage. However the muffler I bought sounds like shit in my opinion. Should've gotten a Borla muffler and used 2.25" pipe. :2cents:
 

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What are the pros and cons of removing the cat? I have removed them off a 3.0v6 and a 3.4v6, mainly because at the time it was the thing to do. Here is SC we dont have to worry about emissions. I now have a 90 4x4 with a 22re 170k miles that runs like a top. I know it gets clogged and all but serves a purpose. Would you cut it or not? why?
Pro's? Well you don't have to replace something that's not there ever again and your exhaust won't smell like rotten eggs anymore.

Con's? Check engine light unless you install the O2 SIM, Illegal in "some states"

Most 22R's/22RE's I've seen don't throw codes when we yank the cats, certain years will though. The only reason anyone should/would remove a cat is it's restrictive (can be a good OR bad thing), and when they go bad some people (like me) don't wanna throw a benjamin at something that could be replaced with a piece of pipe.
 

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Discussion Starter #7
Heres what I know, when I removed mine from my 3.0v6 I loved it. Felt a little more pepy and the sound was great. On my 3.4v6 nothing changed except it through a code, exaust sound was minimal to none. Now debating on the 22re. Just thought cutting it off would help the 90 horses breath.
 

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You'll probably do more harm than good because the motor needs backpressure...
 

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In general terms, you can gain by removing the cats. You typically gain upper RPM power and throttle response, but you also generally lose low end torque.

In practical terms, depending on how new the vehicle is, you might create a problem with the engine management system. As was mentioned earlier in this thread by TrailBlazin', you need to fool the rear O2 sensor into thinking the cat is in and working properly. If you just remove it and don't do anything else, the EMS could go into some version of limp mode and back the timing down as well as dump fuel into it to keep it from burning down.

Here's a case and point for each scenario:
My 1957 Rover with 1992 22RE, de-smogged (except EGR) and no cats. This rig doesn't care, but it does run a tad richer.
And my 1997 Tacoma with 3RZ, the cat got stolen before I bought the truck, so it had a "test pipe" in it...went into complete limp mode and got about 10 MPG.
 

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On my 98' w/5vz fe, I gutted my cat and installed URD O2 simulator.
It seems to have better throttle response high end and low end. It picked up over 3 mpg. If getting it Inspected is not a problem, yank it!
 

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if anybody has a 01-04 2.7 with the oem cat and is thinking about cutting it off let me kno cause ive seemed to having nothing but problems since both of mine were stolen the magnaflows seemed to work for a little while but i belive theyve finally thrown a code i just recently put the 02 simulator on it to combat the code
 

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You'll probably do more harm than good because the motor needs backpressure...
Just compensate with a larger muffler and it's the bee's knee's. :lmao:

JK
 

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with the 02 simulator do you have to have the 02 sensor in the exhaust stream still? or can you eliminate it and the cat completely? i need to lose a cat to put a muffler under the cab when i link my truck.
 

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Interesting...I pulled mine (off road rig only) and seemed to be running fine. But then again I havent put to many hours on it. Does anyone know if this is something that started in a certain gen? like 01-04??

Also if it does go in this "limp" mode...will clearing the code be a temporary fix until I get the simulator??
 

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If it ain't broke don't fix it so leave it be.

Besides, it's agin the federal law whether or not you live in some fucked up state like The Peoples Republic of California.

What are the pros and cons of removing the cat? I have removed them off a 3.0v6 and a 3.4v6, mainly because at the time it was the thing to do. Here is SC we dont have to worry about emissions. I now have a 90 4x4 with a 22re 170k miles that runs like a top. I know it gets clogged and all but serves a purpose. Would you cut it or not? why?
 

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I believe my cats are shot. I had the P0420 code and they rattle when tapped. CA spec emissions so I have 2. Toyota wants like $700 ea.

I have a spare exhaust but it's for a fedral emissions truck(1 cat).

Any thoughts of changing over to that and then just getting one new cat?

Will the ECU notice only one instead of two?
 
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