Oxygen Sensor

[Huw Powell]

What DO they read?

Please give us numbers when you take measurements...

You don't have to buy a smoke machine!  EVERY repair shop worth its salt 
will have one, and they are simple to set up.

All they do is take very low air pressure from a compressor line and 
heat up some special oil to make the smoke, IIRC. Pull a vacuum line and 
pump the smoke into it.

On 5/26/2015 9:11 PM, David Vanden wrote:
> Well I am pretty sure I got them wired correctly.  The only problem, as
> I mentioned is that they are not reading infinite when open.
>
>   There has got to be a way to locate vacume leaks that does not require
> buying a smoke machine.  However, if I did is there a model that you
> recommend.  They come in all shapes and sizes and prices on EBAY.
> Anyway, I will debate it more in the morning.
>
> David
>
> On Tue, May 26, 2015 at 8:17 PM, Huw Powell <audi at humanspeakers.com
> <mailto:audi at humanspeakers.com>> wrote:
>
>     Well, they are just switches.
>
>     When closed they should read zero or as close as possible
>     (definitely less than one ohm).  When open your meter should just
>     read off scale/infinite.
>
>     They won't "vary" anything, the idle switch tells the ECU to use the
>     ISV to maintain about 800 rpm (and kills fuel if it is above ~1400
>     rpm). The WOT switch tells the ECU to go into open loop with a
>     richer mixture for enhanced acceleration.
>
>     - Huw
>
>     I hope you got them wired correctly.
>
>
>         I soldered a set of the throttle body switches I got.
>         Unfortuneately,
>         they read they had some resistance as opposed to being infinite
>         when the
>         switches were not activated.  I don't know what happened to them
>         in the
>         process of pairing and soldering them.  However, they were both at a
>         perfect 0 when activated so I used them.  I don't think they would
>         increase the idle?
>
>         This is a 1987 Audi 4000 Quattro.
>
>