Re: O2 Sensor Works HOW? was: Fw: RE:solder vs. crimp

[16V Jason <jason@scirocco.org>]

At 08:16 PM 11/14/2001, MrAudi wrote:
>i just downloaded 140 messages so i apologize if i repeat anything. the o2
>sensor works with heat. if you were to observe the o2 output on a cold car
>you would see an obvious difference after the car warms up.

Yes, until the O2 sensor reaches normal operating temperature, its output 
is far less than what it should be.  At ambient air temperatures, it's 
close to 0.


>  all new cars
>have heating elements built into the sensor so that it works almost
>immmediatly after the engine is started.

Correct; I can't speak for the 8V, but the 16V Scirocco has a heated O2 
sensor as well.  It's still several minutes before it's heated to normal 
temperature though.

>  the sensor does not measure
>anything outside of the exhaust system. the reading from the sensor is
>analog, but the computer interprets it to be digital (on/off).

Whoa!  Wait a second. :)
You're right about the first part, but the computer most definitely 
interprets it as an analog value.  The O2 sensor, when warm, creates a 
small voltage with the presence of Oxygen.  It outputs 0V if there is no 
oxygen, and about 1V at "full rich".  The engine computer is continually 
altering the mixture to keep these numbers as close to zero as possible 
unless under full acceleration (open-loop full-rich).


>  there for the
>wires would not have to be exposed to the atmosphere. the problem i was
>talking about in regards to soldering the wire is this, solder is made up
>mostly of lead. as we all know lead has a reletivily high resistance to
>electricity. the computer i a car relys on a precise signal from the o2
>sensor. a difference of .01 volt will affect the mixture.

Right -- you got all this right, that's why I'm a little 'fused about the 
computer interpreting it digitally (on/off).

In all reality, a difference of 0.01 volt probably won't make enough of a 
difference to anything -- the variation between two identically produced 
oxygen sensors is probably on that order.  But your point is right -- you 
want to have as direct a connection as possible, otherwise your engine will 
be running slightly richer than the computer thinks it is.


>  so soldering the
>wires with lead solder could concivably affect the sensors operation. ok now
>i need to go bandage the pointer fingers on both of my hands.......lol

That's true.
         It was, however, my understanding that Bosch recommends crimping 
the connection and not using solder for a different reason, namely that of 
heat.  As we know, exhaust systems get very hot... much hotter than 
necessary to turn solder into runny liquid.  Therefore, with the exhaust at 
normal operating temperature, you risk having the connection fail.

Jason





>Jason Neubold
>86 Tornado Red 16v
>85 Tornado Red Audi Coupe GT
>----- Original Message -----
>From: "Fry, Larry" <LEF@chem-tronics.com>
>To: "T Berk" <tberk@mindspring.com>
>Cc: "Scirocco List" <scirocco-l@scirocco.org>
>Sent: Wednesday, November 14, 2001 6:49 AM
>Subject: RE: O2 Sensor Works HOW? was: Fw: RE:solder vs. crimp
>
>
> > Makes no sense that the O2 sensor's designers would have it sampling
> > atmosphere through an electrical wire (even if that could be done, which I
> > doubt) when a simple port in the sensor's body would suffice.  Also, why
> > would it need to sample atmosphere at all?  Within a few tenths of a
> > percent, the concentration of O2 in the atmosphere is a known constant.
> > I'm with you on this one, TBerk.
> >
> > Larry  sandiego16V
> > old (anal) crock and his old 'Roc
> >
> > -----Original Message-----
> > From: T Berk [mailto:tberk@mindspring.com]
> > Sent: Tuesday, November 13, 2001 9:25 PM
> > Cc: Scirocco List
> > Subject: O2 Sensor Works HOW? was: Fw: RE:solder vs. crimp
> >
> >
> > Dave Ewing wrote:
> > >
> > > Totally missing the point.  Solder all the wires you want, even use pipe
> > > solder, I don't care, I just said that the wires to the 02 sensor need
>to
> > be
> > > crimped as per Bosch.  This has nothing to do with strength or type of
> > > solder or any other wires in the whole car, just the 02 sensor wires.
> > This
> > > is why the generic 3 wire 02 sensors that you can get from Bosch have
> > > the crimps on them and includes a note on what to do.  HTH!!
> > >
> > > Dave
> > >
> >
> >
> > Is the WIRE really adding value via exposure to outside air  OR  is the
> > O2 sensor built with little ports or holes that allow for the sensors'
> > element to have an Exhaust vs Atmosphere reading?
> >
> > I have trouble with the idea the WIRE needs atmosphere exposure. Don't
> > believe it.  It's my conjecture a crimp on is easier and makes economic
> > sense.
> >
> > TBerk
> > sometimes Head = Knuckle, sometimes just Hard.
> >
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