Monday, September 27, 2010

Air Flow Meter / Vane or Flap air flow sensor (A.F.M)


A Vane/Flap air flow sensor/meter (A.F.M) basically serves the same purpose as a M.A.F. sensor; Although earlier German and some Japanese manufacturers preferred this method of air flow monitoring.

It's internal function is also similar to that of a T.P.S.

The A.F.M is located on the vehicle's air intake system before the throttle. Instead of having a throttle butterfly like a T.P.S, it has a spring loaded mechanical flap that opens and shuts proportionally to the amount of air entering the engine.
The flap has a wiper arm that rotates against a variable resistor or potentiometer. So the more air flowing in, the further the vane flap is forced in. The wiper arm rotating against the potentiometer causes the resistance to increase, or decrease depending if it is NTC, and therefore the Voltage input signal will increase or decrease accordingly with the resistance readings.



The readings that the A.F.M and other sensors collect will let the ECU know how much fuel etc will be needed.

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