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good news everyone i have found a way to trick you computer effectivly into not throwing a cel with a cat delete! yes some of you may already know this, but awhile back i asked people on this forum how i could get rid of the cel and i got no real asnwers. so here it is


http://forums.evolutionm.net/evo-how...ouler-how.html

 
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good info

 
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This is old news and yes it works but you'll be running a bit leaner as well fyi.

 
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unfortunately that trick doesn't work on all models like my 2004 dx being that the cat is in the header and the alternater is in the way but there are a couple companies that make angled ones like blox,megan,and weapon r. i use the megan style it was 24 bucks and short enough to install without removing the header.
http://www.robearracing.com/pd-megan...or-cel-fix.cfm

 
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Yes you can get angled ones for the lx/dx owners.

 
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so how does it make the car run leaner ???

 
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i have no idea. i thought the secondary cat sensor was only for emissions info (doesnt affect engine like primary).

 
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I don't know im speculating from the lack of back pressure that the cat provides I saw this on my wideband. I ran two setups at one point one with cat and one w/o cat and had to change the tune bc when put the cat back on the car was way too rich to run w/o throwing a code and I was throwing lean codes after taking the cat off. I was seeing 13's high 12's on the wideband at WOT w/o the cat and with the cat same tune i was seeing 11's and low 12's.

 
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i dont really think it can make the car run leaner, yes it tells the car whether it is running too lean or too rich, but all you are doing is giving it a smaller amount of exhaust to take the readings from, and in theory somehow it mixes with some more air or something b4 it gets burned by the thermo couple (thats all an o2 sensor is, it heats up and sends electrical current to the ecu based on how hot it gets or something). You can also take the wire that sends the voltage back to the ecu and put a resistor in that wire. you want to achieve a .45v or less to not throw a cel. now in that cae you could be running too rich all the time and that would not be the best, but it can be done. also as most everyone knows you can get o2 simulators for around 80 bucks. now i dont know too much on how they work, but instead of giving a constant .45v it will vary.

 
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....take the bulb out. no more cel. duh.

 
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I'm not saying the secondary 02 is causing the car to run leaner but there is difference in way the car drives running with and without the cat.

 
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id have to disagree with you on this one unless what you meant was the car runs smoother, quicker cooler and more efficiently. the secondary o2 is just a signal to the ecu that the cat is working.

 
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thats the job of the o2.

 
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I'll have to prove it with the wideband I guess bc I'm not making **** up the tune changed quite a bit just by putting the stock exhaust back on with the cat.

 
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well the cat does change how fast the exhaust flows, maybe thats why. if you look inside, its almost not possible to think air would go thru all that mesh. you have turbo right? the stock exhaust is a huge limiting factor, the pipe diameter is too small so im sure its an airflow issue affecting the sensor readings.

 
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that also bring in delta flow vs. back pressure though right?