Page 1241 - Foton Workshop Manual - Tunland (AT)

ENGINE CONTROL SYSTEM - INTAKE MASS FLOW SENSOR 11-15

INTAKE MASS FLOW SENSOR 11

HOW IT WORKS

The intake mass flow sensor is a frequency based
device. A stable voltage is applied to the heating
wire. The wire is positioned in the air flow system
and is heated by a current generated by the voltage.
The wire is cooled when air flows through it. Heating
wire or heating mold layer is a positive temperature
coefficient (PTC) resistor, which means that when
the temperature drops, the resistance will fall.
Resistance drop is allowed more current to pass
through the wire, to maintain the setting temperature
.The current is converted to a frequency that is sent
to ECM and converted to air flow. The adjustment
of air temperature and humidity is considered
because they also affect the temperature of the
heating wire or the heating mold layer. The intake
mass flow sensor receives the power supplied by
the 12V supplied by the ECM. Also used to measure
the air temperature at the inlet of the turbocharger
compressor. engine control module (ECM) provides
the 5V voltage to the engine intake mass flow sensor
signal circuit. ECM monitors voltage changes due
to sensor resistance changes to determine air
temperature.

Page 1241