Mass flow sensor

mass airflow sensorMAFair mass meterMAF sensormass airflow meterMass air flow sensorAir flow sensorsair mass metersair meterairflow sensor
A mass (air) flow sensor (MAF) is a sensor used to determine the mass flow rate of air entering a fuel-injected internal combustion engine.wikipedia
92 Related Articles

Intake

air intakeengine inletinlet
In automotive applications, air density varies with the ambient temperature, altitude and the use of forced induction, which means that mass flow sensors are more appropriate than volumetric flow sensors for determining the quantity of intake air in each cylinder.
The modern automobile air intake system has three main parts, an air filter, mass flow sensor, and throttle body.

Jetronic

K-JetronicL-JetronicD-Jetronic
A voltage is applied to the potentiometer and a voltage appears on the output terminal of the potentiometer proportional to the angle the vane rotates, or the movement of the vane may directly regulate the amount of fuel injected, as in the K-Jetronic system.
This air mass meter is called HLM2 (Hitzdraht-LuftMassenmesser 2) by Bosch.

Fuel injection

fuel injecteddirect injectionfuel-injected
A voltage is applied to the potentiometer and a voltage appears on the output terminal of the potentiometer proportional to the angle the vane rotates, or the movement of the vane may directly regulate the amount of fuel injected, as in the K-Jetronic system. A mass (air) flow sensor (MAF) is a sensor used to determine the mass flow rate of air entering a fuel-injected internal combustion engine.

MAP sensor

Manifold absolute pressureMAPmanifold pressure sensor
The MAF sensor provides the open-loop controller predicted air flow information (the measured air flow) to the ECU, and the oxygen sensor provides closed-loop feedback in order to make minor corrections to the predicted air mass. Also see manifold absolute pressure sensor (MAP sensor).
A fuel-injected engine may alternatively use a mass airflow sensor (MAF sensor) to detect the intake airflow.

Sensor

sensorsdetectorsensing
A mass (air) flow sensor (MAF) is a sensor used to determine the mass flow rate of air entering a fuel-injected internal combustion engine.

Mass flow rate

flow rateflowmass flow
A mass (air) flow sensor (MAF) is a sensor used to determine the mass flow rate of air entering a fuel-injected internal combustion engine.

Atmosphere of Earth

airEarth's atmosphereatmosphere
A mass (air) flow sensor (MAF) is a sensor used to determine the mass flow rate of air entering a fuel-injected internal combustion engine.

Internal combustion engine

engineinternal combustioninternal combustion engines
A mass (air) flow sensor (MAF) is a sensor used to determine the mass flow rate of air entering a fuel-injected internal combustion engine.

Engine control unit

ECUengine management systemEngine Control Module
The air mass information is necessary for the engine control unit (ECU) to balance and deliver the correct fuel mass to the engine.

Density of air

air densitydensityair
In automotive applications, air density varies with the ambient temperature, altitude and the use of forced induction, which means that mass flow sensors are more appropriate than volumetric flow sensors for determining the quantity of intake air in each cylinder.

Temperature

temperaturesair temperaturewarm
In automotive applications, air density varies with the ambient temperature, altitude and the use of forced induction, which means that mass flow sensors are more appropriate than volumetric flow sensors for determining the quantity of intake air in each cylinder.

Altitude

high altitudealtitudeshigh-altitude
In automotive applications, air density varies with the ambient temperature, altitude and the use of forced induction, which means that mass flow sensors are more appropriate than volumetric flow sensors for determining the quantity of intake air in each cylinder.

Forced induction

forced-inductionInductioninduction system
In automotive applications, air density varies with the ambient temperature, altitude and the use of forced induction, which means that mass flow sensors are more appropriate than volumetric flow sensors for determining the quantity of intake air in each cylinder.

Volumetric flow rate

flow rateflowvolume flow rate
In automotive applications, air density varies with the ambient temperature, altitude and the use of forced induction, which means that mass flow sensors are more appropriate than volumetric flow sensors for determining the quantity of intake air in each cylinder.

Pulse-width modulation

PWMpulse width modulationpulse-width modulated
Both sensor designs output a 0.0–5.0 volt or a pulse-width modulation (PWM) signal that is proportional to the air mass flow rate, and both sensors have an intake air temperature (IAT) sensor incorporated into their housings for most post on-board diagnostics (OBDII) vehicles.

On-board diagnostics

OBD-IIOBD IIOBDII
Both sensor designs output a 0.0–5.0 volt or a pulse-width modulation (PWM) signal that is proportional to the air mass flow rate, and both sensors have an intake air temperature (IAT) sensor incorporated into their housings for most post on-board diagnostics (OBDII) vehicles.

Infiniti Q45

Q45Infiniti Q45 Third generation F50Q45 National TV
An example is 1994 Infiniti Q45.

Oxygen sensor

lambda sensorlambda probeEGO sensor
When a MAF sensor is used in conjunction with an oxygen sensor, the engine's air/fuel ratio can be controlled very accurately.

Open-loop controller

open-loopopen-loop controlopen loop
The MAF sensor provides the open-loop controller predicted air flow information (the measured air flow) to the ECU, and the oxygen sensor provides closed-loop feedback in order to make minor corrections to the predicted air mass. Also see manifold absolute pressure sensor (MAP sensor).

Feedback

feedback loopfeedback loopsfeedback control
The MAF sensor provides the open-loop controller predicted air flow information (the measured air flow) to the ECU, and the oxygen sensor provides closed-loop feedback in order to make minor corrections to the predicted air mass. Also see manifold absolute pressure sensor (MAP sensor).

Spring (device)

springspringsspring-loaded
The VAF (volume air flow) sensor measures the air flow into the engine with a spring-loaded air vane (flap/door) attached to a variable resistor (potentiometer).

Potentiometer

rheostatpotentiometersvariable resistor
The VAF (volume air flow) sensor measures the air flow into the engine with a spring-loaded air vane (flap/door) attached to a variable resistor (potentiometer).

Drag (physics)

dragaerodynamic dragair resistance
The vane moves because of the drag force of the air flow against it; it does not measure volume or mass directly.

Drag equation

aerodynamic dragfrontal areasquare of the car's speed
The drag force depends on air density (air density in turn depends on air temperature), air velocity and the shape of the vane, see drag equation.