Oxygen Sensor

Wed May 27 21:22:06 PDT 2015

I haven't been following every post or detail, to this point, but from the scanning I have done, I am flashing back to my days of fighting the idiosynkracies of my stock CIS URQ. I was helped incredibly by a few experienced listers, who had tread these paths before me. There are too many to name them all, but the late Phil Payne, and Huw Powell, talked me off many a ledge.
What I remember quite clearly is Phil's sage advice that when it comes to getting a CIS car to a decent base point there are 3 main issues to get sorted. They are in order of importance;
1. fuel pressure
2. fuel pressure
3. fuel pressure   
If that isn't sorted, all other specs are chased in vain.
If you want to swap O2 sensors, I can send you a couple.

Dennis 
Denver

-----Original Message-----
From: David Vanden <dvanden46 at gmail.com>
To: audi <audi at humanspeakers.com>
Cc: quattro <quattro at audifans.com>
Sent: Wed, May 27, 2015 11:07 am
Subject: Re: Oxygen Sensor

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.
>>
>>
>>
>>
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