AIR VOLUME (range of 0 to 255, actually 0 to 7)

This is the number that the ECU uses internally for air flow. It is derived from Air Flow Hz, air temperature, and barometric pressure. This value has far more precision inside the ECU (11 bits) but due to technical reasons, the logger only sees the top digit of the whole value (technically, the top 3 bits). This gives us a visible range of only 0-7. Because the resolution is so poor, Air flow Hz is usually used instead to monitor air flow.