Car Advice

What Is A Mass Air Flow Sensor? (MAF)

A mass air flow sensor (MAF) is a device that is between the air filter and the intake manifold. Its job is to measure the mass of the air entering the engine. Note that the word is “mass”, not amount or volume. The mass of the air entering the engine is affected by things such as altitude, temperature, barometric pressure, and other climate factors.

The mass air flow sensor plays a crucial role in working with the computer that controls engine functions keep the optimum ratio of air to fuel to maximize fuel economy and performance. It is very important to ensure the air filter does not become excessively dirty and fits well in order to protect the mass air flow sensor from becoming dirty which will cause it to not work properly.

The most common type of mass air flow sensor is known as a “hot wire” sensor. This is because the sensor uses a heated filament to measure the air mass entering the engine. As air flows across the heated filament it cools it thus requiring more current to be applied to the filament to keep it at the predetermined temperature. The computer measures the amount of current being used by the sensor which tells the computer the mass of the air entering the engine.

Another type is the “vane” sensor which uses a spring-loaded flap that opens and closes as the air entering the engine varies. The flap is connected to a potentiometer (a variable resistor) that changes the current flowing to the computer as the air mass changes entering the engine. A less common style is known as the “cold wire” sensor which uses metal rods positioned in the air flow path that resonate with higher frequencies as airflow increases. That frequency is then transformed into a digital signal that the computer uses to know the airflow entering the engine.

A malfunctioning MAF can cause a number of different issues such as a fluctuating idle speed, low fuel economy, hesitation on acceleration and more. Some MAF sensors can be cleaned but the best way to keep your MAF sensor functioning well is to ensure the air filter is serviced on a timely basis. In Yuma it is fairly obvious that the air filter needs to be replaced more often than in other areas of the country.

Here at Accurate Automotive Attention it is checked routinely any time your vehicle is in for servicing.

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