Quote:
Originally Posted by mad_sb
Yeah, that makes a lot of sense. I remember the 32bit wrx ecu's would go a couple decimal points richer if you removed the rear 02 even if you patched the rom to turn off the CEL.
I know you can log catalyst temperature, even though i assume it is a calculated value. I assume they are looking at the out put of both 02 sensors to determine cat temp and then adjusting target afr based on the desired temp.
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The catalyst temperature estimation is first for OBD/CARB purposes. It could be used for detecting and diagnosing catalyst light off.
While it may be accurate enough for that, I'd be surprised if catalyst temperature were being used for normal heavy load enrichment without an actual EGT sensor. I'm talking about a sensor similar to what you'd find on catted uppipe turbo Subarus.
Usually, for heavy load enrichment control you have the sensor in front of the cat. Then a model estimates the actual cat temperatures, which is pretty complicated. The model has to be tuned according to time delays and gains and such. The cat itself (middle of the bed) is colder than the engine-out exhaust temp during cold start. It's basically like a heat sink. After the cat has warmed up though, it's the hottest part of the exhaust (except maybe preturbo if the car has one). The cat temperature also drops as mileage accumulates on it.