What does the mass air flow sensor do?

WHAT IS A MAF SENSOR?

A Mass Air Flow sensor is also known as an air meter. It plays a fundamental role in your vehicle. Namely, it measures the amount of air (mass flow of air) entering the internal combustion engine.

Based on these real-time inputs, the engine control unit estimates the amount of fuel mass needed to keep air and fuel in balance.

Additionally, note that air density changes with the temperature, pressure, humidity, etc. That is where, again, MAF sensors help. When it comes to measuring the intake air quantity in each cylinder, they are more precise than volumetric flow sensors.

THE TYPES OF MAF SENSORS

Vane Air Flow Meters are an older airflow sensor type. They are further classified into VAF Signal Voltage and Karman Vortex Air Flow Sensors. The latter is newer in design. It uses a moveable mirror and a phototransistor to measure airflow.

Hot Wire Air Flow MAF sensors are advanced MAF sensors and are more common. They consist of a thermistor, a platinum hot wire, and an electronic control circuit. The thermistor is a temperature sensor that measures the air temperature. An electronic control circuit keeps a platinum hot wire at a constant temperature. When the air comes into contact with the heated wire, it cools down. When the temperature difference between the two wires changes, the MAF sensor automatically raises or lowers the current to the hot wire.

There are also Cold Wire Air Flow sensors that work similarly to their hot wire counterparts. However, they have an extra cold resistor that lets them measure the ambient air.

SIGNS OF A BAD MAF SENSOR

Identifying MAF sensor performance issues can be challenging since they are not easy to detect. That is why it is essential to seek expert advice and have your MAF sensor replaced if needed.

Here are a few most common symptoms of a faulty MAF sensor:

ENGINE STALLING WHEN ACCELERATING

A malfunctioning MAF sensor may result in a variety of driving issues, such as engine stalling, jerking, or hesitating while speeding up. You may experience these problems while accelerating or cruising down the street.

Such engine issues may cause accidents and pose a major safety threat to both you as a driver and other traffic participants. Therefore, if you experience any of them, make sure you have your vehicle examined as soon as possible.

RUNNING RICH OR LEAN

Both issues indicate that the fuel-air ratio in the engine is not optimal.

Running rich means that there is too much fuel and not enough air. Some of the most common symptoms of a car running rich are decreased fuel efficiency, rough idling, and black smoke coming out of the tailpipe.

Running lean is the opposite of running rich. That means that there is not enough fuel to match the air entering the engine. That indicates that your MAF sensor is sending inaccurate readings to the ECU that, consequently, fails to blend fuel and air at the proper ratio. In the long run, it may seriously harm your vehicle. Running lean for too long may cause hard starting, hard engine seizures, and engine surging.