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

[bcroe at juno.com]

The purpose of a meter affects everything.  The emissions people 
could care less about transient performance, power, etc.  They 
just want to see that the total accumulated emissions is under 
their limit.  They may be sticky about absolute numbers.

You on the other hand, are very interested in throttle response, 
and power.  Consistancy is much more important than absolute 
accuracy.  The best way to display this info will also vary.  

No, the sensors are not highly precise devices.  To get that, 
each sensor will need to be individually calibrated.  Tuners 
really don't care.  If a certain reading is best power, it is best 
power for you.  It really doesn't matter it it's 12.7:1 or 13:1, as 
long as it always reads the same.  What all meters (and display 
devices) should agree on, is S or Lambda.  That is a null 
point, and error should be relative to that.  

Transient response is limited by the sensor.  Getting electronics 
to keep up is pretty trivial, and easy to verify.  Digital display 
devices are worthless in this respect, but a graph or logging 
(another graph) will handle it.  The speed, direction, and 
approximate amplitude are a whole lot more important than 
the number of decimal places.  This was a weak spot on the 
original DIY-WB, but I found a fix for that.  There were also 
problems with the heater circuit, but those could be fixed too.  

Certainly reading plugs, etc are still valuable.  There was even 
a transparent plug to observe flame color, perhaps upgraded 
now with fiber optics.  

Bruce Roe

12 Nov 2005 Ron Vinsant <ron at poweracumen.com> writes:

> James,
> Your comments are well taken; by me anyway. I have also wondered 
> about calibration issues. I have been using a F.A.S.T. fuel injection 
> system on a 5.7L small block Chevy with closed loop A/F ratio control. 
> I have used a couple of A/F meters to see how my system was 
> controlling the A/F. Spark plug color and exhaust pipe color told me 
> that I should question my control system.  My quest for answers got 
> me to this forum where I have found thought provoking conversations 
> that have taught me a lot. Peters comments have been particularly 
> helpful.  I have never been able to completely correlate one meter
> to another at low flow rates (idle). At high flow rates I get very good

> correlation. I am told this is due to partial gas pressure problems 
> at the sensor tip (any sensor).   Now to my real point. The sensors 
> themselves, as far as I have been able to determine, do not have 
> a specified tolerence. If anyone can point me to either a Bosch or 
> NTK datasheet that says otherwise, I would be greatful.  I did see 
>  a graph faxed to me by a NTK engineer that showed  "typical" 
> voltage vs. A/F but no where was a max or min accuracy stated. 
> He told me that he beleived that the sensors have a 5% tol when 
> NTK manufacturing tests them in a specific production test set 
> up but he could not tell me how this test was done (flow rate, 
> gas pressure,angle of attack of the gas etc.).  I notice that at 
> California Smog test stations a couple of canasters of 
> "calibrated test gases" are used to set up the emission 
> measurment instruments. I was told by a local technition that 
> A/F is derived from the gas content of the exhaust and not 
> specifically measured by a sensor.  Can anyone comment on 
> the issue of measurment accuracy, or even repeatability of the 
> sensors themselves? We could discuss the merits of 
> the rest of the instrument later.
> 
> Ron Vinsant