how does air flow sensor work?

Hi,

The simplest AFMs (Air Flow Meter) work with a flap into the inlet manifold, or into the AFM ass'y. The flap's position is determined by the air flow. This flap is mechanically "linked" to a potentiometer, so the voltage output is given by a formula like AirFlow=V_airflow. V_Airflow is given by k*airflow, where k is a constant. I guess that the pot is usually supplied at 12V, so min airflow = 0 and max airflow=12V. There may be an offset too, but that's took by the ECU.

More modern AFMs are built with a platinum wire heating a set of resistors. The resistors are kept at a constant temperature by the heating wire, and considering the voltage applied to the platinum wire you can deduce the air flow. There, it's a bit more complex as we're talking about a servo-control, but come on, electronics engineers are there to achieve that :-)

Yes, IMHO. Could you tell us a bit more about what you're looking for ? Could you describe your problem, car type and year ? We've got many knowledgeable people here which could well help you.

HTH, G.T