[Wbo2] Using the Bosch WB sensor with L1H1 circuit board

[Peter Gargano]

bcroe at juno.com wrote:
>>when an OEM WBO2 sensor is replaced is the ECU recalibrated?
> 
> How would it be recalibrated?  The ECU accepts the accuracy the 
> calibration resistor provides, which is good enough.  Bruce Roe

All the Bosch LSU sensors I've seen are laser trimmed. The Bosch 
specifications for the sensor make it very clear how the sensor 
calibration component is used to account for variation between 
sensors, so it's not rocket science to create a circuit that will work 
pretty well with the complete range of sensors that may be plugged in.

On the other hand, the problem with the NTK sensors is that Honda/NTK 
never (to the best of my knowledge) made the calibration component's 
use public, and the cal part of DIY-WB circuit was a reverse 
engineering exercise with a bit of guess work.

Also, as a WB sensor ages, it's not so much that the calibration 
points change, but that the sensor's response speed slows right down 
as its active surface is contaminated (or "wears out"). The 
calibration is determined primarily by the active chemical area of the 
sensor. As the pump/sense cells are made from very high temperature 
ceramic materials with very precise quantities of impurities, there's 
a fairly large manufacturing spread that has to be accounted for via 
the cal component. A patent search will reveal that there's a lot of 
work that's been done on refining the manufacturing spread problem as 
manufacturing yields to a large extent determine end prices.

Peter







te.