Sorry for posting so many DIY WBO2 questions but I have to ask this one.

I just plotted the DIY WBO2 site AFR table for v_out vs. A/F. The curve is exactly linear. All of the data sheets that I have read over the past weeks show the L1H1 and LSU4 have non-linear lamba vs. pump current or non-linear A/F vs. vout.

So assuming the DIY WB kit uses linear electronics (i.e. resistors, capacitors, op amps) which it does, then why is the V_out vs. A/F linear. It should follow the non-linear curve of the L1H1 sensor.

It just seems odd to me. Am I missing something as to why the sensor curve and the electronics curves are not both linear? I understand the slope and offset can be different, but I don't get why the linearity is different.
Maybe I should ask this at the DIY WBO2 site.

Thanks,
J

 

pink is linear, blue is DIY-WB ..

X is vout
Y is AFR

 

You plotted AFR vs.v_out and see an exponential curve. If you plot v_out vs. AFR for the logarithmic curve you will see that it is approx. linear while the NTK datasheet curve varies more like a log. curve.
I tried attaching a pic, but not sure if I did it right.

J

 

The Vout term is an even increment of 50 mV per step. The AFR term is not an even increment, it is whatever the AFR is at that Vout.

Plot the FAR (1/AFR) against the Vout term, it is linear.

RBob.

 

I agree that it is linear. The NTK datasheet shows the v_out vs. AFR to be very non-linear at rich readings. I will think about this some more. I had not given it much thought, just noticed that the datasheet differs from the DIY WB table.

J