Oxygen Sensor

[David Vanden]

Yes, now I feel stupid I was measuring milliohms and not ohms.  When I
measure it in ohms it reads infinity.  Another question.  How can you tell
if the Idle stabilization valve is working?

On Wed, May 27, 2015 at 11:19 AM, Huw Powell <audi at humanspeakers.com> wrote:

> Ah, I see, you have an auto-ranging meter, silly me.  I still use the
> Micronta I got in the 80s, which I set to 300 ohms when testing continuity,
> so of course it goes off-range when "open".
>
> Yours selects an appropriate range.  What you are getting is "close enough
> to infinite" I am sure.  You're measuring the resistance of the path
> through any dirt, insulation, and the air and nothing else.
>
> And good catch, you need that idle switch to actuate before
> troubleshooting the idle!  Remember I said what a pain it is to install
> correctly "on the car".
>
> You might want to read a lot of this site and digest/bookmark whatever
> seems useful, especially the middle drop-down on the left (1980-87 4000,
> Coupe, UrQ) since there is a lot about your car there:
>
> http://audi.humanspeakers.com/index.html
>
> I hope you also have the Bentley repair manual by now.
>
> - Huw
>
> On 5/26/2015 10:33 PM, David Vanden wrote:
>
>> Well apparently the button on the bottom wasn't getting pressed because
>> the location of the switch must have slipped, so adjusting the location
>> of the bottom switch tomorrow will be a good place to start.
>>
>> What was weird was after I pressed the bottom switch manually the
>> readings for both sensors began reading infinity when not pressed.  Just
>> before that the top one was reading 20.82 mohms of resistance when not
>> pressed and the bottom one was reading approx. 3.82 mohms when not
>> pressed.  I will have to see what they read tomorrow.  At least I know
>> what I have to do with the bottom switch.  Thanks all.  Good Night.
>>
>> On Tue, May 26, 2015 at 9:39 PM, Huw Powell <audi at humanspeakers.com
>> <mailto:audi at humanspeakers.com>> wrote:
>>
>>     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>
>>         <mailto: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.
>>
>>
>>
>>