I gutted my cat and my truck became brand new again.

 

be nice and save your cat, delete the muffler instead

I love the way mine sounds now afterI took my magnaflow muffler out, 3in pipes from cat back with 4in tips.

 

I've been running a gutted cat for 2 months with no problems (much to my surprise) with ce lights. I have a simm sitting in the shop, but have had no need for it. I don't know what all that nonsense with a downstream sensor causing you to run rich was about, but from everything I have heard and read it is there solely to monitor catalytic converter operation while cruising, so if your upstream is working and your motor is tuned properly it shouldn't be a problem. I have read where people have simply tie wrapped the downstream 02 sensor above the transmission when the bung was eliminated from new exhaust work, and have experienced no codes. The downstream sensor doesn't have anything to do with the a/f mixture if it did the simms would be alot more complex than they are.

 

I put the sim in both sensors. I think by putting a sim in the pre-cat sensor I have send the computer a screwy signal. I'm going to replace the pre-cat sensor with new and I'll let you know how it turned out. Thanks everyone!

 

With amaintainedobd2 motor, cats really don't do alot anyway. I have agood friend who works for a company that makes fuel additives that I have had several discussions about this with. If your engine is close to being 'tuned up' you are running so close to 14.7:1 90% of the time that there is nothing to convert. A converter does help slightly at startup and wot with co output, but not with greenhouse gas emissions. Essentially the exhaust flows over a platinum (they use other metals now also)catalyst and picks up different atoms to change its chemical properties. FE, co (carbon monoxide) picks up an oxygen atom to become carbon dioxide. This works fine until the surface molecules of the catalyst are stripped of there oxygen atoms. The catalytic converter becomes less and less efficient, to the point that it is just a lump of crap inline with your exhaust systemrobbing you of performance and fuel mileage.

 

By all means. The upstream sensor is a completely different animal than the domnstream sensor. The simms are for downstream sensors to eliminate codes.

 

That's really interesting stuff. I read that as O2 sensors age the resistance changes and so does the signal to the comnputer. Here in Ontario the air care inspection just looks under the car to see if the cat is installed. They do not care if it is functioning. Just that it is there. So if your tuned up and gut the cat, you will pass. I think the whole thing is a joke and money grab by the government and companies in bed with the government. It makes the tree huggers feel that something is being done.

 

I was discussing the cooler weather along the coast of SoCal with some friends and suggested that more people drive gas guzzling, V8 trucks without cats so that the weather might get warmer.[sm=smiley2.gif] Maybe my truck with a fully functional emission system doesn't pollute as much as I think it does?[sm=confused06.gif]

 

With as many "gutted cat" threads we have one here i'm supprised someone hasnt writen a good long post about it describing everything, maybe with a DIY. Mopowar I nominate you

 

1) cut the pipe behind cat
2) tie the aft section up out of your way
3) w/ a piece of rod (3/4 rebar, 3/4 rigid conduit, pipe, etc.) and a 3lb hammer beat the hell out the
inards of the cat.
4) periodically start the engine to blow out the material you have destroyed
5) do this until all of the catalyst is destroyed and the cat is completely hollow
6) mate the pipe back together with a slip coupling and secure it with two u-clamps

Note: If you have a nearstock motor,this, at best,might gain you ~5hp over the stock converter, and even less over a high flow cat. I did this because of a poor cam selection that I made. It had me running so rich at idle that, in a short period of time, the cat became clogged. If you are running intake, heads,cam,and GOOD headers you willnotice more. Also, if you do this wear safety glasses and keep them on. Otherwise you may walk around looking like a stoner for a couple of days. Don't ask me how I know.