The Mass Air Flow sensor tells your ECU how much air is being pulled into the engine. It is typically measured with a sensor placed upstream of the turbocharger (a draw-through? setup) but can also be measured with a sensor placed downstream of the turbocharger, usually right before the intake manifold (a blow-through? setup).
TODO:
- MAF calibration table.
- Purpose of “big MAF” housings.
- Details of how the MAF sensors work.