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Old 06-27-2018, 02:36 AM   #14 (permalink)
Cyborg ECU
California98Civic's Avatar
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,297

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: 2,373
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Thanks for all the input guys. The freeway errand tonight lit the P0420 again on the way out. This time I was watching the upstream and downstream 02 data on my UltraGauge and when the light went off I was actively expecting it because the two readings began to move almost in unison for a few seconds. On the way home on the freeway, there was a prolonged period of 5 seconds, 10 seconds, or more when I could see the two readings moving almost in unison. I got lean readings from the downstream sensor as lean as 0.15 volts repeatedly.

I am gonna start a new thread on the persistent rich condition. Once I get a better understanding of the rich condition, I will clean the CAT with an acid wash.

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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