Re: Generic O2 Sensors, and Recommended Connection Methods

[Ian Lomax <sfalfisto@domain.elided>]

The reason most O2 sensor manufacturers don't
recommend soldering wires, is that they actually
breathe through the wires.  An O2 sensor measures the
relative difference between the oxygen in the exhaust,
and the oxygen in the outside air.  Some sensors are
sealed, and get their reference air through the wires.
 Solder blocks this air source, and the sensor will
eventually drift and stop working.

Other sensors (like the Denso sensors I used to work
with) have a source for reference air through the
sensor body.  Ours had a goretex filter to allow air
through, but keep water out.

Just a little bit more semi-worthless knowledge for
the techies out there...

Cheers,
Ian Lomax
--- Johnson David-QA2282
<David.R.Johnson@domain.elided> wrote:
> Given the recent discussion of generic versus
> application specific O2
> sensors for the Milano 2.5 and 3.0 V6, the following
> tidbit may be helpful.
> I found this on the digest clippings section of
> gtv6.org (URL below):
> 
> http://www.gtv6.org/cl_fuel.htm#o2 sensor
> replacement - ford
> 
> "Someone was looking for the Ford 3-wire OS/2
> sensor.  I just put one in my
> 3.0 Milano yesterday.  (Same Alfa number for '91
> Spider). I used Bosch
> 13913.  I bought it at AutoZone for $29.99.  I cut
> of the Ford wires and
> spliced it to the wires.  Just drove it and
> everything is OK. Better than
> $200 for the one with the Alfa wire on it! Be sure
> to use metal crimp on
> connectors for each wire, no solder.  Don't forget 
> to first slip a piece of
> heat shirnk on each indivividual wire and a big one
> over the whole harness
> before you crimp any connectors."
> 
> Clearly I have not tried this, but it would be nice
> to know if it worked.  I
> could certainly believe that with the Alfa part you
> are paying for the
> rarity and the specific connector type, not the
> sensor itself.  Please
> report back to the digest if you try it!
> 
> The last piece of advice about the connections is
> one I've seen elsewhere.
> The integrity of the connections to the sensor is
> very important due to the
> small variations being measured by the ECU.  I'm not
> sure why solder is not
> to be used in this particular case, but in some
> applications I'm aware of
> the wire used for the sensor is of a type not easily
> soldered (maybe
> steel?).  It can be soldered if one has a powerful
> iron (I have a giant
> Radio Shack iron at home that is good for
> connections to massive objects
> which act as heat sinks), and if one is reasonably
> proficient with proper
> soldering techniques, but a sound crimp is probably
> much easier to achieve.
> Solder also has the disadvantage that if applied
> even a little too
> generously in a high vibration application such as
> an engine or exhaust
> sensor it makes the wire too ridgid and the joint
> may crack prematurely.
> 
> Anyone teeing in a mixture meter should also be
> aware of the above advice.
> I would recommend against cutting the stock wire
> when a simple Scotch-Lok or
> similar pathc connector could be used instead.  This
> at least leaves one
> with the option of reverting to the original
> arrangement without having to
> repair the wiring if things don't go as planned.
> 
> Dave J.
> 
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