O2 sensor

Ward Spoonemore spoonie at deltanet.com
Mon Mar 15 17:34:54 GMT 1999



> -----Original Message-----
> From: owner-diy_efi at efi332.eng.ohio-state.edu
> [mailto:owner-diy_efi at efi332.eng.ohio-state.edu]On Behalf Of
> cwagner at info2000.net
> Sent: Sunday, March 14, 1999 7:24 PM
> To: DIY_EFI at efi332.eng.ohio-state.edu
> Subject: O2 sensor
>
>
> I have a question about how to tell when the computer is in closed
> loop mode when a person doesn't have a scan tool.
> I built one of the O2 sensor gauges using the LM3914 chip.  What
> should I be looking for to tell when closed loop is on?  From what I
> have read, I should see the gauge fluctuating several times a
> second (or as close as the eye can tell).  Also, with the O2 sensor
> disconnected from the computer, the O2 sensor does not send a
> voltage during idle even though it is a heated sensor.  I find this
> interesting.
>

There are only three reasons for no voltage at idle:
1. Its to cold at the sense point
2. the o2 sensor is sacked out (old)
3. It is actaul very lean at the sense point, (maybe air leak in the
exhaust)

normaly there is a very good reading at idle. Also there is a high
impeadance 400 mvdc applied to the sensor.

Ward




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