Originally Posted by
Cringer
The ECM LOVES to use the MAF (aka filtered airmass) for its primary source of determining airmass because it is so accurate. The VVE (aka dynamic airflow) table is really only used for reference for transient fueling (when you are opening and closing the throttle since the MAF is slow to respond quickly to changing air mass). Steady state throttle and WOT all goes back to MAF as the primary determination of airmass.
The reality is that the ECM looks at both MAF and VVE to get an idea on what the airflow is and factors in running conditions and atmospheric conditions to make a decision on what is the most appropriate airmass...this would be the dynamic airflow. Sometimes the ECM weights the MAF input more, sometimes VVE more, but it always blends them to some extent. You can log the MAF, VE, and dynamic airflow in the scanner to get an idea on what is going on with this relationship.
Also, during PE the narrowband O2 sensors are useless (they can only be used for stoich reporting). As soon as you go rich in PE, the narrowbands are ignored, and as such the STFT also go to 0. At this time, the car is blindly going off the dynamic airflow it has calculated. This is why you need a wideband, so you can dial in the airflow model during PE.