Oxygen Sensor for 5KTQ

[SJ]

>From: "Ben Swann" <benswann at comcast.net>
>Subject: Re: Oxygen Sensor for 5KTQ
>
> {I assume that the aftermarket sensors which have the short leads have the
> fresh air intake built into the hardware someplace -- prone to clogging ?
> But some sensors, especially the ones with long wires and connector, use
the
> wire insulation as a conduit for fresh air(oxygen). The oxygen supply to
the
> inside of the sensor is via capilliary action in the wires. The wire ends
at
> the connector(clean protected environment) are open to the atmosphere.]
>
> ******Are you sure about this?
>
> I have read in several places - including recent Hot Rod mag article and
> Bosch FI by Probst, et. al. - the reference oxygen (air) is taken throug
the
> small slits on the side of the metal case of the sensor, or small holes in
> the ceramic section.  I have never seen it documented by official
> publication that  air is actually pulled in through the wires.sheath, but
> have heard this through internet emails and just brushed it off as a myth
> being propagated.
>
>  Look at your sensor and you'll see what I'm talking about.  I could be
> wrong howver and would like to know if I am - because then I am sure I
have
> messed up sensor installs with judicious use of tape and sealant when I
> crimp in the stock connector on a generic sensor.  Thing is the stock
> install would have worked the same..Ben

***** I read about the capillary action of the wires somewhere. Now that I
need the information, I cant find it.
The closest info I have found is  > http://www.forparts.com/Bos02update2.htm
"Reference outside air for the interior of the thimble comes from a hole in
the sensor shell, or through the wiring connector."

Most sources dont get into the specifics of how  atmospheric air gets into
the sensor.
Here is a typical example >
http://www.turbobricks.com/resources/O2sensors.pdf
"The inner cavity is open to the atmosphere which serves as the units
reference gas."

But if you read the Bosch design info >
http://www.boschusa.com/AutoParts/FAQs/OxygenSensors/
You will see the reference to a "double laser-welded stainless steel body".
Nicely welded . . .no air gaps shown on the drawing. So how does
atomospheric air get in?

http://forums.beyond.ca/showthread/t-60393.html
"Make sure that if you do remove the o2 that you disconnect the wiring to
the sensor as well. Leaving the o2 open to atmospheric air while being
connected to the ecu will result in "less than ideal" operation ;)"


Solid information on this is hard to find. Air must get in somehow. The
outside shell shows no openings. And if the openings are so small that you
cant see them . . .then they are subject to clogging also.
The only way for air to get in is where the wires come out, or at the
connector end.

I brought up this topic hoping someone else knew more than me.
Then again, maybe this is just an urban myth.

SJ



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