Oxygen Sensor Operating Temperature

[Alan Kramer]

Is there a minimum recommended operating temperature for an oxygen sensor?  
If so, will the heating element in a 3 or 4 wire sensor be sufficient to 
maintain that temperature, or must the exhaust gas be at or above that 
temperature?

The reason I ask is that the table I have that compares voltage to mixture 
ratio explicitly states the relationship was derived for a sensor 
temperature of 1200F.  If the temperature of the combustion gas is lower, is 
the curve offset or skewed, or is it just that the response of the 
electrochemical cell is slower?

Does anyone know what the exhaust temperature just prior to the cat on a 4kq 
would be?  My feeling is that it is signifiantly lower than 1200 F.  I'm 
running a 4kq header & downpipe on the '83 CGT and have my two oxygen 
sensors (1 for computer & 1 for mixture guage) located 6" after the 
termination of the downpipe next to the tranny.  When driving at WOT, the 
oxygen sensor voltage does not go above 0.65V.  I have verified operation of 
the WOT switch, fuel & control presures, flow rates, etc... and all is in 
spec.  Although it is an '83 CGT, it was "upgraded" to CIS-E.  Mixture is 
set correctly.  Even adjusting to full rich settings (verified by idle 
stumble, fuel smell out of exhaust (no cat)) and sending the computer into 
open loop still does not result in readings above 0.65V while driving.  
Swapping oxygen sensor leads to the guage does not change the results.  My 
thought is that it has to do with the temperature of the sensor...

Thoughts anyone?
Alan

'83 CGT  http://www.geocities.com/audikramer/index.html
'86 CGT
'86 4kcsq



Thanks,
Alan
_________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

Share information about yourself, create your own public profile at 
http://profiles.msn.com.