On mine max rich is around 1.0 volts, mids scale gives me around 0.45-0.6 volts, low end drops off around 0.1.5 - 0.2 volts. 

 

Thanks Ed.  That is, of course, exactly what it should read.  The next step is to temporarily re-install the old mixture gauge, and compare it to the EM-2.  I will also measure the O2 sensor voltage at the same time.   I may even pick up another O2 sensor, just in case. 

 

Is the O2 sensor you are using a heated 3/4 wire unit?  If so I am wondering whether you might possibly have a ground loop feeding heater voltage onto your sensor lead?

 

 

Good thought, but it's just the cheap single wire unit that Tracy and Finn are both using.  

 

Thanks,

Rusty (mourning the loss of my 6 months paid severance vacation) 

 

 

One thing I have heard is that with the single wire (Unheated) O2 sensors you may get erratic readings until the sensor has been heated sufficiently by the exhaust.  I would think that would not take  over 2-3 minutes depending on what power levels you are operating at. 

 

I use the heated O2 sensor as that gives you readings immediately on start up.  But, the non-heated type should get up to operating temps in a minute or two I would think.

 

Ed