Lambda & Lead

[Ed Lansinger]

Degradation of the Lambda sensor is a function of just how much lead it sees over time, 
but there's no question that it does happen.  Some sensors are more resistant than 
others.  Bosch, et al, have ratings of the form "40,000 km life @ 0.5g/l" for their 
sensors.  You might be able to get exact numbers if you talk to them.  A friend who runs 
Turbo Blue racing his Buick Regal GN has observed that the signal degradation is 
principally a slowing of response time.  There are other effects which are probably well 
documented in the SAE literature.  What you can do is go to Radio Shack, get a cheap 
digital multimeter, splice it into the Lambda sensor line, Velcro it to your dash, and 
simply watch it.  A good sensor will transition from lean (about .02-.03 volts) to rich 
(about .70-.80+ volts) faster than the update rate of the DMM.  As the sensor gets 
contaminated (over hundreds or thousands of miles, not dozens) the transition time will 
slow noticeably.  The dynamics of your system will determine how slow is too slow.

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Ed Lansinger
General Motors Powertrain
Powertrain Control Center
Premium V Software & Calibration Group
Milford Proving Ground, Milford, MI
elansi01 at mpg.gmpt.gmeds.com  8-341-3049  (810) 684-3049
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