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Old 06-20-2012, 11:22 PM   #119
arghx7
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11:1 is normal, even on a nonturbo engine. They have to keep the cat from overheating at high rpm. Engines with more expensive components can handle higher heat or can reduce exhaust temperatures. This is a $25,000 car. It's not going to use expensive materials, expensive engine architecture, and expensive control strategies.



target AFR has already been logged with an OBD scantool, see top graph. Nobody's logged open/closed loop yet and posted it--a generic scantool can actually read it if set up properly. You also can look at estimated catalyst temperature with a general scantool. Nobody's posted it yet, but I suspect it's around 950C at the limit. If it gets hotter than that, the catalyst will prematurely age. It's not something an owner would notice but it affects in-use emissions testing from the EPA.
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