Re: Oxygen sensor question

[HaleyD@YANKELOVICH.COM (Haley, Doug)]

Huw Powell wrote:
>Does 0.5 volts  really correspond to the ideal mixture?  Todd P and I
>were wondering about this recently...

If I remember correctly, the Oxy sensor wants to be around 0.72 volts
at Stochiometric (sp?).  When I logged one of mine, it was around .65v
to .75v idle (to pass emissions this varies a bit by state), .77v cruising,
 .82v (normally aspirated) WOT, .88v full boost with turbo.

I used data sampling to get average voltages, since as you point out,
the voltage is constantly dithering around the target values.  And yes,
the input impedence has to be very high for the meter (my first attempt
at an air/fuel meter actually affected the operation of the circuit).

Of course this may be totally different for different vehicles? Although
I would think it would be standardized by Bosch for cicuit design.
Your Voltage May Vary (YVMV)

Doug Haley
'92 Ur-S4
'99 A4 1.8tqm