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The common assumption is it adjusts the idle mixtures, while that is true it also changes the air fuel ratio for RPM and loads much higher than just idle. The CO2 adjuster is a 5K potentiometer that the ECU continually reads, if you turn it full rich or full lean the ECU senses that as a fault and uses a default value instead of the pot - this can be seen in the below log captures, as the AFR goes lean and reaches the peak it drops back a bit richer as the ECU thinks these is a fault due to high/low volts.
So, I rigged up a pot I could adjust while on the move as well as at idle and using the MAF adjuster loggged air fuel ratio from a wideband oxygen sensor along with a heap of other things, one being RPM. The higher the RPM and load the less change, above 3K RPM is hardly any change and full throttle shows no change with a mega rich 11.0:1 AFR all the time.
The same test with the same results was done on another 90 series, interesting huh
At idle....
2000RPM ....
3000RPM ....
So, I rigged up a pot I could adjust while on the move as well as at idle and using the MAF adjuster loggged air fuel ratio from a wideband oxygen sensor along with a heap of other things, one being RPM. The higher the RPM and load the less change, above 3K RPM is hardly any change and full throttle shows no change with a mega rich 11.0:1 AFR all the time.
The same test with the same results was done on another 90 series, interesting huh
At idle....
2000RPM ....
3000RPM ....
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