Fw: Wide band O2 ????

[jdbubb at ix.netcom.com (Dan Bubb)]

Dammit! I read the quote and thought "that's all effed up"!
What I meant to say was "1. control the current to it's heater to maintain the sensor temperature in a
narrow temperature range despite exhaust heat input (or lack thereof)"

Anyway, this sentence applies to the wide band O2, but in any event the heater is always on for both the narrow and wide band O2's.
The heater is there, as you state, to get the O2 sensor to temp faster, but it's also pretty far down the exhaust on a 16V and may not stay hot enough at a consistent idle. Note, the 16V has a heater, but the 8V does not since it's sensor is 6" from the head.
As is turns out though heater resistance increases quite a bit as the heater gets hotter, so current becomes negliable. If you look at a schematic for the 16V engine wiring you'll see the heater is getting 12V whenever the fuel pump is running.


  ----- Original Message ----- 
  From: mr.utility@highstream.net 
  To: Dan Bubb 
  Cc: scirocco-l@scirocco.org ; Ron Pieper 
  Sent: Friday, October 24, 2003 2:29 PM
  Subject: Re: Fw: Wide band O2 ????


  Quoting Dan Bubb <jdbubb@ix.netcom.com>:


  > 1. control the current to it's heater to maintain the sensor temperature in a
  > narrow band despite exhaust heat input (or lack thereof) 

  > Dan
  > 
  > 


  Correct me if I am wrong, but the only time the heater is used is at initial 
  start-up, when the sensor is cold?  I was under the impression that that was 
  the only time the heater is used, to further diminish emissions when the O2 is 
  cold and not yet able to function completely....

  David


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