Originally Posted by ekaz
Those values are pulled off a table and not based on O2 readings, it is calculated on the base airflow for a stock application, once the airflow is changed (by adding a cai for instance), those calculated values are no longer accurate.
All I am trying to make clear, it that the PID is not your actual AFR. It is a decent "guess" on a stock engine, but once modifications are made, you need a wideband to get a true reading.
It is certainly not as valuable as a wideband.
I have seen even on heads/cammed setups that they hold the same level of accuracy so I'm not sure what to make of that. But, after looking it up, you're absolutely right. I stand corrected.