I am checking my S5 N/A's air flow meter (E2 <-> Vs), and to my surprise its resistance does not change monotonically. Resistance goes from 300 when close to 80 when open, both within FSM specification. But there is more to that, as the reading actually goes up from 300 to 600 before going back down.

Is this normal?

 

Yes, it's not linear. I find that the AFM's rarely go bad unless dropped/flapper doesn't move. What lead you to checking it, some other issue?

 

airflow meters of all different kinds (hotwire, flapper, vane, Karmann Vortex) are designed to have more sensitivity/precision under low load, emissions controlled driving. none of them have fully linear characteristics to my knowledge