[V8] New O2 Sensor- Whhhhaaaatt

[Ingo Rautenberg]

Yes to the sensor on the back of the head.  The initial Service  
training document even has a graphic on the proper sensor Ohm  
readings, which, surprisingly are not in the four book volume.  There  
it only states that the sensor reading on a 'cold' engine at room  
temperature should read between 1.5 and 3 Ohms.  (mine read at 1.46 - 
close enough).  Now I need to check the resistance when it's hot...

As to the second sensor at the front of the engine -- I'm not sure if  
it's a switch or variable resistance as well.

Ingo
'84 urq - '91 V8 5 spd - '93 V8 - '90 V8 (project)



On Jul 17, 2006, at 12:26 PM, dsaad at icehouse.net wrote:

> I will probably confuse everyone here - but I seem to recall that  
> the sensor at
> the back of the right head is described in the service manual as  
> both a "switch"
> meaning it is a on/off type device only, and as a "sensor" meaning  
> that it has a
> variable resistance according to temperature. I believe the correct  
> part is the
> variable resistance type - and it has a white plastic connector.
>
> The on/off type sensor has a black plastic connector.
>
> They are physically interchangable.
>
> The moral is to be careful at the parts department - maybe even  
> bringing in your
> old part to match.
>
> Dave
>
>
>
> Quoting Ingo Rautenberg <i.rautenberg at waratap.com>:
>
>> Funny...I'm going through this same thing right now (but with  
>> Bosch 3-wire)
>> on the '93.  I'm guessing that the coolant temp sensor at the back  
>> of the
>> pass. side (USA) head is not functioning properly.  Will replace  
>> and see
>> what happens.  Figure a 20-30% improvement in fuel mileage will  
>> help with
>> the possible $4/ gallon fuel they're anticipating...
>>
>> Ingo
>> '84 urq - '91 V8 5 spd - '93 V8 - '90 V8 (project) - '93 90s
>>
>> ----- Original Message -----
>> From: "rudedog714" <rudedog714 at alaska.net>
>> To: <V8 at audifans.com>
>> Sent: Saturday, July 15, 2006 2:15 AM
>> Subject: [V8] New O2 Sensor- Whhhhaaaatt
>>
>>
>>> Here's a head scratcher, at least for me. I just replaced my O2  
>>> sensor,
>> went with the 4 lead type. Now the thing is fine until it warms up  
>> the it
>> seems to run too rich. Flat stretch of road at a steady 65 MPH  
>> should give
>> me 25-28 MPG instead it's 15-17 MPG then it'll go back to normal  
>> for a bit
>> and back to running too rich. I've double checked all the  
>> connections and
>> the extra ground lead is on a bolt behind the drivers side head.  
>> What's
>> going on here, I'm baffled. Thanks in advance for all the  
>> incredible Audi
>> expertise, William
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>
>
>
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> all contributions welcome!