Correct A:F Ratio @ WOT?

[Stephen Webb]

> Maybe I am confused by the usage of AFR as measured on the exhaust side with
> a sensor,
> and the actual input AFR.
> See what I mean, or am I out to lunch?

I see what you mean.

I think what's going on is that on the one hand you are talking about the
air and fuel inputs, as you say, and on the other hand the original post
was referring to the indicated AFR as the O2 sensor sees it.

My understanding of the O2 sensor is that it measures the exhaust gas
for oxygen content (as referenced to ambient, I think).  Small amounts of
oxygen (big "oxygen gradient" between the sensor and the atmosphere) cause
high voltages, loads of oxygen in the exhaust (low "oxygen
gradient") cause lower voltages.  Changing timing can change the
combustion, and burn more or less of the mixture, leaving less or more
oxygen in the exhuast.  The "indicated" AFR (inferred from exhuast oxygen
content) will thus stray from the actual AFR input.

Maybe that's why people say O2 sensor AFR gauges are a poor way to tune.

Now maybe something different alltogether is going on.  

-Steve


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