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Old 05-17-2020, 11:38 AM   #1 (permalink)
Cyborg ECU
California98Civic's Avatar
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,097

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 66.42 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
Thanks: 2,310
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18:1 AFR is "cleaner"?

So, assuming the catalyst is fully warmed-up, doesn't a graph such as this indicate that an AFR of 18:1 is better for emissions than stoich? I realize we can only be in lean burn under light throttle and load conditions. Nonetheless, at 18:1 only 02 is higher than at 14.7:1. That seems gooder for everybody. So 18:1 is simply better, no? Why aren't all cars in lean burn under light load and part throttle and steady cruise on freeways?

See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.

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