Homemade A/F Meter

[am018]

What type of meter are you reading the signal with ? -- it must be digital
or have a high impedance pre-amp stage or the current drain will drop
nearly  all the voltage across the internal ressistance.
Earth wires were added to sensor because grounding problem caused a lot of
trouble in service with  low  signals if you need a heated sensor better to
go for a 3 or 4 wire type.

A Mcf

Khoo Teck-Khoon wrote:

> 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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