Quote:
Originally Posted by Walt Fricke
The result is a kind of dynamic average for best part throttle fuel economy.
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Respectfully, I think this is incorrect. As the then-lead aftermarket Mustang powertrain calibrator for Roush explained it to me, you can "think of the catalyst as an oxygen bucket." Catalyzing HC requires the cat to give up oxygen, and catalyzing NOx requires the cat to accept oxygen. Obviously, if the bucket were full or empty, one of these two functions would be impossible. "Dithering about stoich," which is what the ECU tries to do during cruise, is all about keeping the cat neither full nor empty,
for emissions control purposes.
$0.02