cutting the cat

[Ridr]

I am getting ready to run new ,better flowing exhaust and am thinking I would like to just do away with the cat , my question is , what do I do with the sensor that I see is plugged in towards the rear of it ??

 

[bajacalal]

But thats illegal :nono:
Its supposed to make the check engine light come on, if the cat is not working or has been tampered with. Summitracing.com I believe sells an eliminator kit that plugs in and tells the computer what it wants to hear.

 

[Ridr]

I have heard that before about summit , I have searched their catalog and website to no avail and nobody seems to know a number for this magical part

 

[explorer]

Eliminating the cat will not give you any advantage on an otherwise stock or lighlty modified engine. In fact on 2.5, it actually hurts low end performance significantly, and mid to top end gains little other than more noise. On a 4.0, still not a significant power increase, and again more noise. On top of that, your adding to emmisions. I may sound like a wacko enviro, but I assure you I'm not. I have respect for the land and other people who use it. Work in a shop for awhile, and you will be a little more sensitive to whats coming out the exhaust of vehicles.

 

[bajacalal]

I think they are called "oxygen sensor eliminators". Theyre on there but, I thought that they had them under the "summit" house brand which was cheaper. You'd probably want the chrysler style plug. Anyway, rather than searching I would just give them a phone call. Explorers right though, although I have heard of people passing the emissions sniffer w/ no cat, is it worth it?

 

[Ridr]

I am not wanting to cut if for power , it has 98,000 miles on it and I figure instead of replacing it with the new system it would be better to eliminate it. Do you know how long these things last ?? If it still has life left in it , I'll just keep it

 

[explorer]

If the engine is running properly, not dumping excess fuel, then they can last a long time. I've replaced mine on my TJ once at about 75k, with another OEM cat. That was with a lot of banging the exhaust on the ground, and having dirt packed around it constantly. If the core isn't rattling, and the Jeep runs good, its fine. If the core is deteriorated, it usually starts to restrict flow, which will make a usually obvious sifference in performance.

 

[Ridr]

OK , I am looking at the replacement option. If I get an aftermarket cat (say one from summitracing) will I be able to hook my sensor to it?

 

[bajacalal]

If it doesn't include the OBDII required sensor fitting, a sensor "bung" (which is correct word and refers to the hole, by the way) can be welded on. Summit also has these, search for " weld on bung".

 

[Ridr]

OK , that will work , thank you all for your help !!

 

[dmillion]

Eliminating the cat will not give you any advantage on an otherwise stock or lighlty modified engine.

Yep. Old habits die hard. Back in the 70's, when catalytic converters first started appearing on cars, they were pretty restrictive and they were just an add-on to engines that hadn't been designed with them in mind. As a result, back then, taking off the cat could make a meaningful difference.

Not anymore. Today's cats are much better designed than the first ones were, and today's engines are designed from the ground up to work with the cat in place. As a result, as explorer has said, taking off the cat will not make enough difference in power or gas mileage to matter. If you got an extra tenth of a horsepower out of an otherwise stock engine by taking off the cat you'd be doing good. And I'm no environmentalist whacko either, but taking off the cat will measurably increase emissions, so it seems to me like a pretty bad tradeoff.

 

[PapaPump]

AND it makes your exhaust smell like raw fuel (to me anyway), and it is stupid loud. oh yeah, and it makes the jeep slower off the line, in my experience. mine was seriously smashed and rattling. after it started rattling it was balls slow, so i took it off. without the cat it felt like the jeep was gutless off the line. i have since replaced it. i know this is all just from my butt dyno, but that's just my $.02.