[Diy_efi] WBO2 and AFR

[Adam Wade]

I'm curious why anyone would need extreme precision
from a WBO2.  If you are tuning several identical
engines and have tuned for best power, then measured
the AFR with a WBO2 sensor throughout the operating
range, you could use those values to then tune the
other identical engines to best power without
requiring a lot of dyno time.  But since you can't
know the best power target AFR at any given operating
conditions with any given engine, how important can
calibration be, except in terms of repeatability? 
Tuning to a particular AFR without dyno testing to
confirm best power is going to be a crap shoot anyhow,
and you're unlikely to get closer than about 85-90% of
best power at any given set of operating conditions by
the "pick a number" method.

Incidentally, no one responded to my query from the
other day.  So I'll ask again; anyone know what
happens to a WBO2 (or other measurement of residual
oxygen in the exhaust) when you take an engine
operating at steady state and retard the ignition
timing a good bit?  The answer to this question
actually ends up raising significant questions about
the relative importance of precision calibration in a WBO2...

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