Quote:
Originally Posted by Phantom
"Catalytic converters generally function efficiently only when the incoming mixture is within about 4% of stoichiometry, or a lambda range from .96 to 1.04. Let's return to our last example above. At 1.03, lambda is narrowly within acceptable lean limits. But if this borderline lean condition persists over a long period of time, the catalyst will slowly degrade as a result of the excessive heat it generates while cleaning up the exhaust stream."
From http://www.austincc.edu/wkibbe/lambda.htm |
Saying it will slowly degrade the catalyst in general seems kinda weird since 2-way catalytic converters were around for a decade before 3-way cats were and they functioned well. Catalyst heat is only a function of how much stuff it catalyzes, and I think that all three reactions are exothermic, so if we take one reaction out of the picture there will tend to be less heat, barring of course some sort of condition like a misfire that increases the amount of HCs in the exhaust to be catalyzed.