moranor said:
the cats absorb heat when they are in place... so the post cat sensors will run hotter when there is no cat... on some cars is is a problem i dont know if this is the case on the e46...
whats wrong with mini cats all they do is block some of the heat so it does not throw errors... software would be better only because you can tune the car at the same time...
If you want to take out the cats take them out, why have a mini cat to fool the system, if you can easily do it with two resistors? Also, the heat should never be a problem, and the cats require heat to operate properly, but there job is not to reduce heat, it is to convert mainly CO to CO2 (etc). Lambda probes are designed to handle extreme temperatures (the pre-cat ones also have built-in heaters and endure much higher temperatures without cat to cool down the air, and they are essentially the same thing, just double.)
It is not the heat that cause the errors.
Hmmm, okay maybe I should explain this a bit better:
Firstly, the engine and the cats need to be up to operating temperatures for catalytic conversion to take place. So you have to drive around for about 30km. Then it also only works properly in a semi-steady state. So say you are cruising at a constant speed, say 120km/h on the highway. Now the ecu will start to cycle the air/fuel ratio slightly for the CATS to work properly and to monitor their operation. So the pre-cat sensors will record this cycling, but the post-cat sensors should show a steady reading. If the post-cat lambdas don't show the steady reading, the ECU assumes the cats are not operating correctly and throws a CEL.
Electronic cat-fooler will just keep the reading at the expected steady reading, and voila, the ecu thinks the cats are 100%
