Several engine components work in harmony to ensure your car travels from point A to point B. Two such engine components are the MAF and MAP sensors, which are responsible for calculating the amount of air that enters the engine.
The engine management control system needs to know how much air and fuel are in the engine for it to accurately control the spark timing and air-fuel mixture ratio.
The fuel injectors measure and atomize the fuel that enters the combustion chamber. It also ensures that the fuel gets into the engine at the right time, but the air that enters the engine is more of an unknown quantity. Attitude, humidity, density, and temperature can all affect the volume of the air that goes into the engine.
Hence, the engine management control system needs a heads-up on the quality and quantity of the air that enters the engine, and that’s where the MAF and MAP sensors come in. I’ll precisely explain MAF vs. MAP sensors to see how these sensors work and how they differ.
MAF is an abbreviation for mass air flow, which measures the total volume of air that enters the engine and forwards the information to the PCM so it can send in the right amount of fuel into the engine. Practically, the PCM does not send fuel into the engine.
It, however, tells the fuel injector the right amount of fuel to send and at the right time. Therefore, for an engine to receive a balanced air-fuel mixture, the MAF sensor should function properly so it can always tell the PCM the quantity of air entering the engine at all times.
MAP is an acronym for manifold absolute pressure. It is a sensor that watches the real-time changes in vacuum pressure and tells the car computer how to adjust the fuel input so there will be a balanced air-fuel ratio.
If the air-fuel mixture is not balanced as predefined by the manufacturer, the engine will misfire, stall, run rough, or stutter. Most supercharged and turbocharged vehicles use a MAP sensor to track the real-time changes in vacuum pressure since the engine features a turbo or supercharger pressuring the intake track.
MAP vs. MAF – What’s the difference?
While both MAF and MAP sensors measure the air volume that enters the engine, the major difference is how they come up with their readings or the approach they use in measuring the air that enters the engine. Another difference between them is their locations.
In theory, the MAF sensor measures the total amount of air entering the engine, while the MAP sensor only measures the air pressure in the intake manifold. Both of these sensors signal their reading to the car computer, which uses the information to determine the right air-fuel ratio to send into the engine for optimal operation.
Since the air pressure in the intake manifold can change with attitude, the manifold absolute pressure is there to give the onboard computer heads-up of what’s happening in the intake track.
As you have seen, both of these sensors have similar functions, but how do you know if you have a bad MAP or MAF sensor?
Whenever a MAF or MAP sensor starts failing, you will experience poor fuel economy, the check engine light will appear on the dashboard, there will be black exhaust smoke from the tailpipe, and the engine will run lean. Other possible signs are unstable engine running, hard starting, engine misfiring, and reduced engine power while driving.
Testing both sensors is the only way you can determine if the mass air flow or the manifold absolute pressure sensor is bad. Often, you will observe those symptoms not because any of the sensors are bad but because they are dirty and need to be cleaned. In such a case, all you need is to clean the sensors using a MAP or MAF cleaner.
Do cars have both MAP and MAF sensors?
In actual sense, cars have either MAF or MAP sensors. The mass air flow sensor tells the engine management system the total volume of air that enters the engine. On the other hand, the manifold absolute pressure sensor only monitors the air pressure in the intake manifold.
The MAP sensor is used in conjunction with the manifold air temperature sensor, also called the intake air temperature sensor.
Most cars only use the mass air flow sensor instead of both sensors. But if you have a supercharged or turbocharged engine, the engine will use both mass airflow and manifold absolute pressure sensors.
Where are MAF and MAP sensors?
On most cars, MAP sensors are mounted on the intake manifold. On the other hand, MAF sensors are mounted in the housing before the throttle body.
In a situation where a vehicle has only a MAP sensor, you will see the sensor on the intake manifold right after the throttle body. The sensor is placed on this position so it can accurately measure both the air volume that enters the engine and the air pressure in the manifold.
But if the vehicle has both mass airflow and manifold absolute pressure sensors, you’ll see the MAP sensor before the throttle body. Where there are both MAP and MAF sensors, the MAP sensor only measures the air pressure in the intake manifold.
MAF and MAP are essential sensors that help to determine the amount of air that enters the combustion chamber. These sensors send this information to the ECU, which uses the data to determine the proper air-fuel mixture ratio to send into the engine.
The only difference between them is that the MAF sensor measures the volume of air that enters the engine, while the MAP sensor measures the air pressure in the intake manifold.