O2 Sensor.. Alert ! ..and new info

[scottb]

Wil, you should be a mediator. Maybe baseball can use your services. Well done!

[911pcars]

Wil,
The person you probably spoke with was a sales rep. I think the answer from a tech. rep would be different (and probably more correct).

BTW, not to take anything away from Wayne's store, but Sumitt Racing sells a 4-wire replacement sensor for about $50.

Sherwood Lee
http://member.rennlist.org/911pcars

[Bill Verburg]

I can see that no one bothered to check the link I provided. Oh well, here's the relevant text;

"Sensor design
The oxygen sensor (see Figure 3)is a galvanic oxygen concentration cell with a solid state electrolyte. The solid state electrolyte is an impermeable zirconium dioxide ceramic unit stabilized with yttrium oxide. It is open on one end and closed on the other. Mounted on both the inner and outer surfaces are gas permeable platinum electrodes. The platinum electrode on the outside acts as a miniature catalyst to support reactions in the incoming exhaust gases and bring them into a state of stoichiometric balance. The side that is exposed to the exhaust gases also has a porous ceramic layer (Spinell coating) to protect against contamination. A metal tube with numerous slots guards the ceramic body against impacts and thermal shocks. The inner cavity is open to the atmosphere which serves as the unit’s reference gas. The two-state sensor operation is based in the Nernst Principle. The sensor’s ceramic material conducts oxygen ions at temperatures 350oC and above. Disparities in oxygen levels on the respective sides of the sensor will result in the generation of electrical voltage between the two surfaces. This voltage serves as the index of how much the oxygen levels vary on the two sides of the sensor. The amount of residual oxygen in the exhaust fluctuates sharply in response to the variation in the iinduction mixture’s air/fuel ratio. Oxygen sensitive voltage generation ranges from 800 to 1000 millivolts for rich mixtures to as low as 100 millivolts for lean mixtures. The transition from rich to lean corresponds to 450 to 500 millivolts. Heated oxygen sensor An electric heater element (see Figure 4) is used to warm the ceramic material when the engine is operating at low load factors. At the higher load factors the sensor’s temperature is determined by the exhaust gas. The heated oxygen sensor helps ensure low and stable emissions due to the consistent maintenance of optimal operating temperatures."

For more details check the link, the info was supplied by the Bosch engineers that designed the O in our cars. The wires are just wires and can be cut, spliced, crimped, soldered etc w/ no liability.

[Doug Zielke]

Thank you, Professor Verburg!
(My unplugged O2 sensor also thanks you).

[911pcars]

Thanks Bill. Took the words right out of my mouth. :-)

Sherwood Lee

[Wil Ferch]

Guys:
Since this same topic was discussed on Rennlist, and since the same Bosch rep was involved, see his ( emotional) response to my further questioning. Still...there is SOME info that is still useful ( construction differences between Bosch and others, etc).
Here it is...

Listers:
I forwarded the opposing ( but seemingly valid) view held by many on this List that O2 sensors don't behave as I said they did...based on my Bosch tech's description ( re: air passage under wire insulation).
Here is his ( admittedly emotional) response.
I guess decide for yourself,..I offer this only to complete this sorry chapter. Since ( in this case)I didn't ask permission to repost his reply, I will maintain his anonymity, in fairness to him. I had , however, gained his permission to paraphrase his first response to me.

--Wil Ferch

( address snipped)..Bosch rep response follows:

Look at my email address...you are getting the information from the horse's
mouth, that should be reason enough.
Believe what you want, but it is the truth and we make over 3 million per
year(Do you?). I refuse to argue as I know what is correct. The truth is
that these sensors pull a vacuum on the wire harness drawing in air through
the harness(yes air can actually pass between the insulation and the wire)
and replenishing the chamber(hence the importance of the sealed connector as
water could possibly be drawn in). I do not know what you mean as
"communication" but read my earlier posts as to how the sensors function.
The sensor generates voltage in a rich gas environment...bottom line. The
reference air is necessary for the ion activity in the Zirconia and is
replenished through the harness....bottom line. In fact we test our sensors
by pressurizing the wire harness and making sure that no air escapes from
the sensor body..hence it is totally sealed. We also submerge the sensor in
a water bath while it is operating, just to make sure that no water is drawn
into the body and rendering the sensor useless. Your Ford friend is
referring to our competitor's sensor NTK, which has a breathable membrane on
the sensor body to counteract contamination problems that Bosch sensors
don't experience.
Your friend is incorrect(in the case of the BOSCH sensor), this is
interesting because a lot of our business is with Ford. The rest of his
comments are similar to ones I have stated previously.
Why are you arguing these points, I am trying to help you but you are making
it difficult and are pushing me away from the Rennlist. It makes me angry
when people assume certain things(with nothing to back it up) and want to
argue their point. I have data, do you? When you have data that shows that
the BOSCH sensor does not pull a vacuum on the harness and breathes through
the sensor body come talk to me, otherwise assumptions mean nothing.
Replace your sensor with a three wire Bosch sensor as it is the best sensor
in aftermarket, drive your car, and please leave it at that. I shall post
no more answers to O2 questions(universal replacements or any
other)....thanks to the response of arguments that I have had to write
rebuttals for.
I have no problems with the statements from the Ford guy, except that he is
referring to a NTK sensor and not a Bosch.
In reading the email below you are still missing it as far as how an O2
sensor functions. See my earlier replies as to how it actually functions(or
search the web). Engine compartment air is not bad, but water and other
contamination could be introduced if the connections are not sealed, harming
the sensor.
I was a credible source for O2 information but my comments will no longer be
available.

-----Original Message-----
From: Wil_Ferch at praxair.com [mailto:Wil_Ferch at praxair.com]
Sent: Wednesday, August 28, 2002 8:57 AM
To: XXXXXXXXXXXXXXXXX
Subject:


XXXXXX:
I appreciate the information given me earlier on the various O2
sensors...however...
I've taken a lot of grief about the assertion that O2/air having a
"communication" path back to the computer inside the cabin of the car ( you
and I had a similar discussion at the very beginning. My question at that
time centered around ..."How can air travel under the wire insulation AND
through the various plug connectors along the way"..I still have trouble
with truly believing that...yet I went ahead with your description anyway).

The core question is whether there is indeed a small hole or gap at
the sensor body itself to admit air. If so, I then have other concerns
about weather-tightness , and such, since the sensor is located directly
behind the rear wheel in a 911. If so, is the sensor protected by a
silicone-rubber or Teflon boot, etc .. ?

See the attachment below as a representative sample of how this was
received by the technically-astute members of our web group. I think you
will find it interesting, and hope to hear from you ( pro or con)...about
this.

Thanks!
-- Wil Ferch

(snippeed attachments of various Rennlist responses..)

[Doug Zielke]

Oh, oh, we've made a Bosch guy *mad* at us for our temerity for questioning his..... authority.

I guess we can't ask him then, how all this transfer of air takes place when one splices (solders) the single wire O2 sensor as per Bosch instructions?

[scottb]

After reading the tech rep's response, a phrase came to mind: "Get a grip..."

Me thinks he takes this just a wee bit too seriously.

[radcon]

This bosch rep is full of crap, I'll bet 1K on it just to make it interesting. There is no flowpath for air to get from the computer to the sensor. Does the air somehow pass through the electrical connector that is located in the engine compartment of my SC? Not a chance! This guy(a sales rep) probably spends most of his time peddling spark plugs and such to auto parts chains and doesn't have a clue about the actual design of their products. I've met more than a few salesmen at car dealerships who didn't know a darn thing about the car they were trying to sell me- not engine size, horsepower, not even what the standard equipment was. If someone who's trying to sell you a 20k plus car is so uninformed, what makes you think a sales rep peddling $5 spark plugs and $40 O2 sensors knows anything?

[jwill911]

After all the discussion. What is the best replacement 02 sensor to get for an `87 Carrera? Obvoiusly based on price alone not the Porsche branded one. I have no problem splicing and shrink tubing the proper connector to the universal one. I'd just like to get the proper one for the best price I can. Where would I get one that fits that description?

Thanks,
jw

[911pcars]

I think the Bosch "rep" is getting some false info too. When questioned about it, he should have verified it instead of relying on his 02 sensor belief system.

JW,
If you don't mind splicing and cross-referencing wire colors:

3-wire sensor from JC Whitney @$52.95
4-wire sensor from Summit Racing @$50.00

Sherwood Lee
http://members.rennlist.org/911cars

[stlrj]

Now that we got that out of the way...

NTK makes a four wire sensor for Chrysler that I use in my 86 Carrera. $61 at the auto parts store but you need to splice a male end to your harness.

Tweeks sells an 02 sensor for an 86 3.2 for $239.99. I wonder what it is at the dealer?

A little closer inspection on the 02 sensor says assembled in USA, NTK, 5233038.

It seems that NTK Technologies and NGK spark plugs are the same company.

So, if you like NGK spark plugs you might just like NTK 02 sensors too.


Cheers,

Joe

[Early_S_Man]

It would appear that particular tech rep has been wearing his underwear a bit too tight!

It doesn't take an advanced degree to tell that he has been blowing way too much smoke and offering little, if any, substance in his rebutals. Current sealed, and waterproof O2 sensors are a relatively new development ... and the rep has totally misrepresented the reason for the sealing! Any ordinary electrical connector interposed between sensor and DME would prevent the 'so-called' replenishment in his 'junk science' theory! Besides, there has been no evidence given that replenishment is required! I have seen no information about O2 sensors that indicates any oxygen is 'consumed' on the reference side of the sensor ... so, why would there be any need to replenish?

I have seen plenty of sales and tech reps over the years that have gotten aggresive and hostile when their technical 'info' has been questioned as presented, and this guy is no different!

[scottb]

I just purchased a unviersal sensor from another vendor (Pelican didn't sell the universal one), and I soldered the wires, then covered them individually with heat shrink tubing, and then covered all of them with a larger piece of heat shrink. The spliced universal sensor was intalled yesterday, and the car seems to be running fine. I suspect that I could have simply taped the wires (thought not a good idea given the proximity to the exhaust system), and the car would still be runnining fine. I highly doubt that air is somehow running up the newly-spliced wires. It just doesn't make sense. The tech rep has got to be wrong.

(FYI, NGK/NTK makes a three-wire sensor that will work in the car. I decided to keep my car Bosch, however.)

[jmohn]

While I appreciate Wil's attempt to get some solid info on the O2 sensor debate, I'm not sure I totally accept the Bosch rep's explanation.

I don't know where the reference air for the Bosch sensor comes from (nor do I care, to be truthful) but, I do know a spliced in Ford (Bosch) sensor works. A couple years ago I was checking\adjusting everthing on my 951, air-flow, air temp., throttle switch, etc. (hey, it was Saturday and better than mowing the lawn) and when I probed the O2 sensor with a meter I got nothing; obviously, I wanted to replace the non-functioning O2 sensor. I shopped/asked around and was advised (reputable source, even gave me the part number) the Ford sensor was the same except for the connector. I bought one (about $30), spliced on the Porsche connector (3 wires, individually soldered and shrink tubed) and installed it; I brought the car up to normal operating temp. and probed the sensor connection at the DME - it dithered beautifully, just like the book said it should. Now, the 951 sensor makes a connection at the firewall (behind the engine) so it's reasonable well protected from road "crud", but I know there is no continous "insulated wire" to the DME. So, I don't know where the ref. air comes from, but I do know the non-Porsche sensor works.

Have fun you guys,

Jerry M
'78 SC (O2 sensor? we don't need no stinkin' O2 sensor)

[island911]

Originally posted by Early_S_Man
... and the rep has totally misrepresented the reason for the sealing! Any ordinary electrical connector interposed between sensor and DME would prevent the 'so-called' replenishment in his 'junk science' theory! Besides, there has been no evidence given that replenishment is required! I have seen no information about O2 sensors that indicates any oxygen is 'consumed' on the reference side of the sensor ... so, why would there be any need to replenish?

Exactly! This is what I was hinting at back on page 1 of this thread.
quote:--------
What if the reference side does not need to breath?
What if the reference side does not "use-up" any O2? . . .and yet some tech guy assumes it must ? ? ?
------
Exec. Summary: oxygen is not consumed. . .

SO this is the way it sits in my head, but I've tried to make it presentable here;

This O2 sensor is measuring a force, emf (eletromotive force) to be precise. Keep in mind, measuring a force, and using a force, are two different things. For example, if you step on a bathroom scale, it does not consume you as it gives you a force measurement. . . .lets hope not, those whom get consumed with their weight. . . oh-oh, right . . .eh-em
Back to this O2 sensor, if your measuring device has high impedance (no current leakage) it will not consume what it is measuring.
The captive O2 will stay as a reference, just as your bathroom floor provide an opposite reference force.

Say there *is* a bit of "leakage" (voltage; not something on your bathroom floor):
If sensor equipment does consume what it is measuring, electrons are what it is consuming. The Oxygen is still there; just a bit naked, in the form of an ion.
Furthermore, the O2 sensor then has become an Oxygen-ion generator. (meaning it will push/pull electrons on/off O2 molecules.)
In a closed O2 reference this is still workable. The sensor is grounded allowing the captive oxygen ions to steal electron to replenish themselves as needed.
It work for me . . .but then so does unplugging the damn thing.

[Wil Ferch]

Guys:
Allow me some more comments on this, since I had the most dialogue with the Bosch rep:
1.) He adamantly says he's a Development Engineer and fairly bristled when I suggested that he may be a Sales Rep..and after I said that my experience along these lines sometimes has me encounter sales-types that give well intentioned, but false answers.
2.) To give him some slack, there is evidence that suggests that NTK's are not sealed..and that Bosch are sealed. Over-generalized, perhaps, but I'm sticking with Bosch.
3.) O2, IMHO, can be consumed if if the encapsulated air ( O2) exists at some times at room temp, and at other times close to 600 degF. Either the contained gas will experience high pressure swings, or it's allowed to "breathe" in some fashion.
4.) I've experienced the phenomena where air breathes under the wire insulation...this is not too far fetched. His story breaks down when he says the air path continues to the computer ( through the connectors....THAT doesn't make sense). Compromise...maybe the air can flow to the first connector, where there is no moisture and road grime, and therefore is OK.
5.) Here are the Bosch equivalants for mid 80'd Carrera's, again from the Bosch rep, who says these have proper ceramic characterisitics, and proper heater wattages:
15725 ( 0258005725)...universal type
15726 ( 0258005726)...universal type

Notice the relationship between long and short part numbers..


13913, 3 wire Ford...I think it has 8" leads
13953, 3 wire Ford...I think this has 16" leads
He suggests sticking with the universal connectors for the universal kits, and also suggests soldering and heat shrink the Porsche connectors when using the Ford parts.

--- Wil Ferch
pioneering straight info has its risks!

[island911]

Originally posted by Wil Ferch
. . .pioneering straight info has its risks!

You got that right!

Can we now get back to our regularly scheduled information regurgitation?

[Doug Zielke]

I've experienced the phenomena where air breathes under the wire insulation

Yeah?
A phenomena you say?
And what *kind* of wire, cable, insulation etc. exhibits this "breathing" phenomena?

[91C2wrencher]

Lets remember some basic laws of physics. Nature abhors a vacuum and is always moving towards equiliberum, so as any of the air (20.9% oxygen) is consumed(mininmal) the trapped and resident air in the connecting cable is adequate to replenish it. (think about it as the motion in a freshly poured Guiness). This zirconium oxide cell is the very same technology that we sell for flue gas emissions on industrial burners only much smaller. The resident air and "tramp" air in the cable provide enough O2 to run a sensor for 100's of years.