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Re: O2 sensors (longish)

On Tue, 3 Nov 1998, John Larson wrote:

> "Established fact"? By whom, and how? By what standards?

Well why don't you cut some old ones open (pipe cutter or lathe works
well) and see these differences?????

> Are you aware, that in addition to 1 and 3 wire units, there are 2 and 4 wire
> sensors.

And for all you Q-listers out there reading this you can use a 4-wire
"universal" sensor on your car. The 4th wire is simply a redundant
ground... You just won't be using it.
> Have you ever wondered why there are multiple numbers of 3 wire
> sensors specified for various years and models of Audis?

Ummm... as Dave wrote before, there is a different PN for different
connectors, different wiring harness lengths, different Pin-stamping on
the shell etc...

> Without further
> investigation, I would wager that each number specified corresponds with a
> different emissions system, i.e., CIS, CIS-E, Motronic, etc.

What do you want to wager? :-)
As far as O2 sensors for Audi's go we can see the following:

(Thankyou Ben Howell for your awesome research.)

If that is true why does the Late MC (200tq, dual knock, K24) have the
same Pn(034 906 265 F) for O2S as a 3B(200tq 20v) and a 7A(Coupe Q)?
Last I checked a MC and 3B used different engine management...

Or how about the 034 906 265 C which fits a 4k and a early production
Coupe Q?  I'm not following your argument. BTW- the 034 906 265 C also
is used on a MC motor (K26).

The best part is when looking at the Bosch part numbers.
Their book lists the O2S with PN 13019 (doesn't list 10 digit complete #)
to fit the following vehicles:
89-91 200
89-91 200q
85-87 4kq
87    5kt
86-88 5ktq
88-89 80
88-91 90q
95 A6/S6
90 Coupe Q
92-95 S4
95 S6
and misc. VW's.

Kinda funny, must be the same sensor then they just put different
harnesses on them depending on the vehicle...
So, essentially as far as we are all concerned, an oxygen sensor is an
Oxygen sensor is and oxygen sensor.  Now, you may look at different
sensors  and say wow, that NTK sensor is tiny compared to the Bosch and
the AC sensor.  Guess what, they both read 500mv at Stoich.  Now, they
may perform a little differently.  The NTK may be operating and at
temperature a full 15 seconds before the AC sensor, is this going to
effect you?  Well we could get into an ecological debate about that...

> I'm convinced, having worked on Lambda systems since 1976, that it's wise to
> stick to the products specified for each application. And that's what I am
> going to do, both on my own cars, and those of my customers.

You can do that if you wish... But for me, I don't mind having a Bosch O2s
on my Audi even it has Ford pinstamped on the shell...if it costs 1/3 of
the "Audi" sensor and all that is required is some soldering and shrink
wrap. I have been told that you can even buy Audi connectors and assemble
them yourselves... that would save the splice job. Besides, I have seen
some pretty racy wire
insulation on these other brands sensors as well... One was close to RS2

Just a few late night thoughts...

Brendan Rudack AKA "Bendy"
'98 A4tq 
'88 90q 2B tq pro-rally ride
Fenton, Michigan