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Old 12-21-2011, 06:59 PM   #33
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Joined: Apr 2003
Location: Long Beach, CA
Oddometer: 11,887
Originally Posted by roger 04 rt View Post

Yes, agreed it switches between something above the set point and something below it. When I use the term setting closed loop AFR to 14.2, I mean that's the center of a range, the average AFR. In the case of 14.2, I'm running 13.7 to 14.7 at the moment but am still conducting tests.
The 14.7 ratio isn't a set point, it's a coincidental average of the Exhaust Oxygen swings. I know, it sounds like I repeated what you just said, but I didn't. The thing is, the ECU and the catalyst require the high and low cycling exhaust oxygen levels, not the average value. The oxygen-rich and oxygen-lean swings are for the catalyst to 'breathe' so to speak. The catalyst needs the high and low oxygen swings, not the average value.

The modified O2 sensor signal from your LC-1 causes the ECU to alter the exhaust oxygen swings, which affects the chemical processes going on inside the catalyst. With the modified O2 sensor signal, the ECU feeds the catalyst more fuel, along with enough oxygen to complete the 'chemical combustion' (aka: oxidation) process going on inside the catalyst. This is dangerous.

When the catalyst is provided a sufficient quantity of oxygen and fuel ingredients, the oxidation process in the catalyst becomes hot enough to turn the stainless steel exhaust components into solder. There is a way around this.


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Poolside screwed with this post 12-22-2011 at 06:01 AM
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