Mass Air Flow Sensor

Manifold Air Flow Sensor (Hot Wire)

The maf sensor is located on the air intake after the air filter before the intake manifold.The mass air flow sensor sensors the amount of air drawn into the engine and sends a voltage to the ecu. A voltage is applied to the maf sensor to heat up the hot wire to about 100 degrees Celsius. The wires resistance increases as the temperature increases which allows less current to flow through the wire. when air passes through the maf sensor, it cools down the hot wire therefore resistance goes down and current flow increases getting the hot wire hot to its maintaining temperature. The amount of current required to get the hot wire back to its temperature is then converted by a chip in the maf to send signal voltage back to the ecu.

The hot wire has a self cleaning process. when the car is shut down, the hot wire heats up to about 1000 degress celsius to clean any dirt or grime stuck in the hot wire. If the hot wire gets contaminated and starts giving wrong readings there is no other way of fixing it then just to replace the piece.

without blowing air through maf.

blowing air though maf.

When i did the experiment i connected my bosch map sensor with the pinouts from the above table. i had to use to power supplies. A 5v and a 12V.without blowing air into the map i got 1.07v and when i blew air into it it increased to 2.2v.manufactures specifications tells us that the maf should have 0.5v at signal without air blowing thought it and out maf gave us 1.07. I think our maf is near to specification as we did the experiment in the class and there is a little bit of air flow as to the specifications are made to be done when the maf is connected to the intake and there is hardly any air flow when the engine is off. So i would say this maf is working properly.