Date:         Fri, 15 Sep 2000 08:22:41 -0400
Reply-To:     Lawrence Johnson <larry_avery.johnson@SYMPATICO.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Lawrence Johnson <larry_avery.johnson@SYMPATICO.CA>
Subject:      Re: Ground for O2 Sensor?
Comments: To: kenneth d lewis <kdlewis@juno.com>
Content-Type: text/plain; charset=us-ascii

kenneth d lewis wrote:

> Larry;
>         I also grounded the AFM housing long ago for static reasons. I
> would think all grounds should be at the same potential. For that reason
> I added grounds to the right head and block to chassis.

I did too. The entire ignition current is flowing into the head. The head
(without the added ground) is attached to the block by a rubber gasket so the
only real conductor connecting the two is the antifreeze which could
accelerate electrolysis in the head/gasket/block area.

>         FWIW, I checked a spare, three wire O2 sensor.

So, I'm not the only nut on this List. I did the same thing and came to the
same conclusion.

> The heater circuit
> is isolated from the metal body of the sensor.Hence no grounding is
> attained here. Since the O2 output is less that one volt, readings could
> very easily be messed up by bad grounds on the engine adding or
> subtracting their voltage drops.

I don't know if I can blame my added ground connections but 'Fritz' runs very
smoothly, pulls well, and consumes gas normally. If all engines ran as well,
the traffic on this List would be much less.

-Larry and the Katzenjammer kids:
'86 Syncro Westfalia 'Fritz' with VW WBX 2.1L (smoother)
'86 Syncro Doublecab 'Hans' with Subaru WBX 2.2L (stronger)