How Does the Flow Meter Work?

A flow meter ensures that our car’s engine works properly, that the ignition spark is perfect, that the air-fuel mixture is optimal to provide maximum performance while generating the least amount of polluting waste. Also known as MAF (by air mass meter) It is one of the key components of an electronic fuel injection system in any car with a traditional engine.

According to the Operative Network of Spanish Scrap Yards (RO-DES), the flowmeter is also known by the name debimeter, and consists of an electronic device “responsible for measuring the air mass entering the intake manifold from the outside” and sending this information to the car’s brain. the flow meter It is present in diesel and petrol cars, at the air filter outlet and on the suction line. Thus, the path the air has to travel is already filtered to reach the cylinders and start the combustion process.

How does the flow meter work?

The flowmeter has a wire that is electrically heated (hot wire). A temperature sensor installed near that cable measures the temperature of the surrounding air. When the motor is idling, a small amount of air flows around the cable, so a very low electrical current is required to keep it at a temperature of 120°C). The moment you step on the gas, more air flows over the hot wire. This passing air cools the cable, and the more air flowing through it, the more electrical current is required.

Electrical current is proportional to the amount of airflow. A small electronic chip installed in the flowmeter sensor converts the electrical current into a digital signal and sends it to the motor brain. The control unit (ECU) uses the flow meter signal to calculate the amount of fuel to be injected to the cylinders. The goal is to keep the air/fuel ratio at an optimal level. The ECU and flowmeter work hand in hand, making hundreds of decisions per second to adjust the mixture.

In addition, in vehicles equipped with a automatic gearbox, the ECU uses measurements from the flow meter to determine the timing of changes. If the flow meter is not working properly, the transmission may also operate differently.

How do I recognize problems with a damaged or defective flowmeter?

Flow meter problems are common in many vehicles, and usually this is because the sensor may be contaminated or damaged. For example, in some engines, a faulty flowmeter can cause us to start but not be able to move. A poorly installed or clogged air filter will also help make the flowmeter more likely to fail or over-wet (even if it’s washable).

A bad flow meter cannot measure the amount of airflow correctly. This causes the ECU to miscalculate the amount of fuel injected, which can lead to jerks on acceleration that we didn’t feel before, until it simply decides not to inject fuel into the cylinders; that’s why we can’t move forward. When a flow meter is not working properly, the engine trouble warning light will normally illuminate or the annual service (or engine, if modern) message will appear on the instrument panel.

Some of the most common malfunctions that we will notice in the event of a faulty or broken flowmeter are:

  • acorns
  • A reduced acceleration
  • Lack of response to acceleration requests
  • Black smoke comes out of the exhaust pipe
  • Worse fuel economy
  • Rough idle
  • It’s hard to start (and it’s not a problem with the alternator, battery, or starter motor)
  • Engine Failure Warning Light or Service Message
  • Types of flow meters

Mechanical systems: These flowmeters come with a butterfly valve in the collector empty space when they need to allow air to enter as it is drawn into the combustion chamber.

Electronic injection systems: With this type of flow meter, the sensor sends the measurements to the ECU so that it knows how much fuel to inject for optimal combustion. In addition, this system is also responsible for activating the exhaust gas recirculation systems, such as the EGR valve.

What maintenance does a flow meter need?

As mentioned above, the air filter can extend or shorten the life of a flow meter. The function of this part is to clean the air coming from outside so that it reaches the engine as cleanly as possible and to achieve a good combustion. However, if it gets clogged with excess dirt, it won’t let the proper amount of air through. It is recommended for this replace the air filter between 10,000 and 15,000 kilometers depending on the use and type of roads we drive on.

On the other hand, if the crankcase oil It is in good condition, it helps in the proper functioning of the flow meter. This is because the oil gases that come out of the crankcase and are recovered in the inlet can also damage the flowmeter. Likewise, carbon is one of the issues that can affect the sensor, which normally shows up through: circulating on low bends usually on a diesel (especially in the city). The humidity It can also affect the flowmeter, and while less likely, it’s not impossible on the coast.

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