Homemade A/F Meter

[Khoo Teck-Khoon]

Help!

I have found diagrams for a A/F Meter using a O2 sensor. However, my car 
does not come with a O2 sensor. Therefore, I have to source from other 
places. Anyway, I have found a 2 wire O2 sensor which I have tested to 
be 1 wire for the voltage signal and the other seems to be for the 
heater element. Is there a 2 wire heated O2 sensor? Because there only 
seems to be signal when I connect 1 wire to the multitester and the 
other connected to the neck of the O2 sensor, no signal if I connect to 
the other wire.

Anyway, the problem is with the signal...very low voltage i.e. about 
0.05 to 0.075 volts. The voltage seems to change whenever I lean/richen 
the mixture. But the voltage should not be this low, right? I have 
placed the O2 sensor about 2 feet away from the collector pipe but it 
seems to be sitting quite high...maybe the O2 sensor is not getting 
enough of the exhaust gas?

Somebody please help me with this problem soon because I intend to get 
the LM3914 to built a better monitor.

Regards,
tkkhoo at hotmail.com

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