At 02:23 PM 7/8/2012, neil n wrote:
>Would an analogue VOM be better for measuring voltage at O2 lead?

Typical analog meter will load that circuit down severely, giving you
and the ECU both false readings.  A 100,000 ohms per volt meter$$$ on
the ten volt scale should be usable but will still load the signal
some.  Your little pocket meter is 2,000 ohms per volt, you won't
even get a reading.  A VTVM (Vacuum Tube VoltMeter) (10 megohms) or
its transistorised equivalent would be great if you could find one in
the wayback machine.

The DMM (10 megohms) will work fine for steady signals.

To watch them change, build or buy from Ken Lewis a bar-graph meter
based on the National Semiconductor LM3914 chip.  His have a
ten-segment display, but if you want you can stack the chips to have
as many segments as you desire for more resolution.  Great chip.  Or
use an oscilloscope with a x10 probe.

Yours,
David