In modern injection engines, the supply of the required amounts of fuel at different engine modes is controlled by an electronic system. The system needs various sensors, among them there is a sensor that is responsible for the air flow for preparing the air-fuel mixture. This could be an absolute pressure sensor (MAP) or a sensor mass flow air (mass air flow sensor). Often the air flow sensor is also called a flow meter.

DBPs have recently become more widespread and have practically replaced air flow sensors from use. DBPs are cheaper and easier to manufacture, are not so capricious and are less likely to fail. But quite a lot of cars still drive on Russian roads with mass air flow sensors, and domestic cars still come off the assembly line with these sensors.

What is a mass air flow sensor

A mass air flow sensor is essentially a hot-wire anemometer hidden in a plastic case. A voltage is applied to a thin platinum filament, which heats the platinum red hot. The flow of blown air cools the thread depending on external conditions. All data on changing factors is received by the electronic control unit and, according to the data received, regulates the fuel supply for the processed air flow.

The mass air flow sensor is located between the throttle valve assembly and the air filter housing. The sensor is connected to the housing and assembly using wide corrugated pipes. The pipes must be reliable and the connections sealed to prevent additional air flow from the outside.

Signs of a malfunctioning mass air flow sensor

You can determine the likelihood of a malfunction of the mass air flow sensor by some deviations in the behavior of the car engine:

• - idle speed increased to 1500 rpm,
• - the engine stalls periodically, especially when braking the car,
• - the engine runs unstably, there are jerks and jerks when driving,
• - the engine diagnostic lamp in the Check Engine cabin lights up occasionally or is constantly on,
• - fuel consumption has increased.

It should be noted that all these signs are quite conditional; in order not to make mistakes in diagnosing faults, you need to check the system using a scanner or computer stand.

Factors affecting the serviceability of the mass air flow sensor

First of all, you need to pay attention that the mass air flow sensor requires very careful handling.

The platinum thread can be damaged if you do not wipe the sensor carefully. Dirt and oil should not be allowed to enter the air flow sensor. Let's say if the engine smokes and consumes oil, oil soot clogs the sensor and disables it.

Due to improper adjustments or malfunctions in the ignition system, popping noises occur in the intake manifold, which can destroy the fine platinum hair.

There is another characteristic defect, in all respects similar to a malfunction of the mass air flow sensor. This is damage to the injector pipe (corrugation) connecting the sensor and the throttle body. Additional air leaks occur, and the air-fuel mixture becomes leaner in composition.

Damage to the sensor may occur due to impact. This can happen as a result of a traffic accident.

You must not forget to change the air filter element in a timely manner. Dirt and dust from the air filter get onto the platinum threads of the flow meter and damage the sensor.

How to check if the sensor is faulty

The first step is to remove the sensor and inspect it externally. Two platinum threads must be intact. With broken threads, the air flow sensor is 100% faulty and cannot be used for further use.

If you suspect a malfunction of the mass air flow sensor, you can check it in the following way. You need to disconnect the sensor plug and start the engine. If before this the revolutions were lower, but now they have increased to 1500 and the engine has regained its former power, there is a high probability that the mass air flow sensor is defective. The fact is that when the flow meter does not work, its function is taken over by the throttle position sensor. The fuel mixture is enriched, the car becomes more responsive. True, fuel consumption becomes even higher.

Of course, the air flow sensor can be checked using an oscilloscope, scanner or computer stand, but it is not always possible to use such devices for a number of reasons. But trying to install another, obviously working mass air flow sensor is very simple. If after replacement no changes in the vehicle dynamics are detected, the problem is not with the sensor. We need to look for another reason.

Replacing the mass air flow sensor

Replacing the mass air flow sensor is not difficult even for a novice in automotive repair.

As a rule, the sensor is held in place by corrugated pipes; for reliability, the connections are tightened with clamps.

To replace the mass air flow sensor, you need to loosen the clamps, disconnect the plug from the wires and remove the sensor. Install the new sensor in the reverse order.

Good day to everyone who reads us! Continuing to cover consumer topics various types fuel consumption of modern cars of domestic and foreign brands, I want to talk today about this topic: how does the mass air flow sensor affect fuel consumption. If you are unfamiliar with this abbreviation, then below I will tell you what it is and about its modest role.

Every car enthusiast knows that a car engine can operate in different modes. Each of them will require a special working mixture of air and fuel (for example, gasoline, diesel fuel). It is these functions that the mass air flow sensor, abbreviated MAF, is designed to perform, which is designed to calculate the mass flow of air that is required for the successful operation of the cylinders.

The design of the sensor includes a thermal anemometer device, which actually measures the mass flow of air. But all this is good as long as the mass air flow sensor is fully and properly functioning. At the same time, this device is quite delicate - it is enough to wipe it with a rag and it can be damaged. At the same time, it cannot be repaired; there is only one option left - complete replacement.

How to recognize that the mass air flow sensor has failed

Above, we figured out how the sensor for monitoring incoming air works. Now let's move on to what the main symptoms and causes of its malfunctioning condition are. Most often, this can be indicated by engine operation with characteristic interruptions at idle, as well as loss of the previous dynamics when accelerating the car.

Too low or too high speeds can also be a characteristic sign of a malfunction in the mass air flow sensor. The worst situation is when you cannot start the car engine, and this may also be due to the air sensor. Even if the flow meter is in full working order, it is not uncommon to experience depressurization at the point where it connects to the corrugated hose, which often cracks during operation.

How else to recognize a case when the sensor does not work? A control called Check Engine can easily come to the rescue. However, in order to understand that the problem is the sensor and not something else, you will need to connect a computer with a diagnostic program. And finally, in order for your mass flow sensor to last as long as possible, you should replace it in a timely manner, as well as regularly monitor the condition and wear of the piston rings and seals. Their wear can cause increased oil accumulation in the crankcase, after which the film covers the sensor and disables it.

How the device works

To understand why it can affect fuel consumption, and how to deceive the mass air flow sensor, let's try to figure it out further. For every stroke of work power unit it should contain approximately 14 parts of fuel and 1 part of air. If the relationship is disrupted, this will cause excessive fuel consumption or a significant reduction in engine power. It is the sensor that must measure the ideal volume of air entering the cylinders. It makes calculations and transmits this information to the on-board computer, which calculates the required volume of gasoline based on information about the volume of air.

You can find the sensor itself in the area between the air filter and the engine intake. At the same time, the mass air flow sensor does not stop working for a second. After all, with each press of the accelerator pedal, the amount of incoming air changes, and, accordingly, it is necessary to recalculate how much fuel the engine requires.

Therefore, not only can you deceive, but you won’t be able to adjust the sensor just like that. As mentioned above, it fails with any unsuccessful touch or interaction with aggressive chemicals. It is the lack of possibility of repair that is the most significant drawback sensor, since it is not cheap.

Effect on fuel consumption

The sensor itself is quite picky about the condition of the air filter element. When it is heavily contaminated, the platinum air flow sensor spirals are also contaminated. They can be washed, but only specialists can actually do this without harming the device. Therefore, today the air measurement sensor is being replaced by other equipment - a pressure measurement sensor.

It works on a different principle. For the mass air flow sensor, it is important to diagnose the volume of air entering the cylinders, on the basis of which the amount of fuel will be calculated. Based on the air density, it may be necessary to adjust the readings of the sensor itself. To get out of this situation, an air temperature sensor is also installed next to the mass air flow sensor, but this already complicates the electrical circuit.

As you can see, dear car enthusiasts, with a faulty mass air flow sensor there is no way to reduce fuel consumption in your car. If you have carried out diagnostics and are convinced that this is the reason, hurry to the nearest service station for a prompt replacement. And we will soon meet you on the pages of new notes. Happy everyone!

The mass air flow sensor (MAF) can be characterized by two main parameters.
The first is the amount of air passing through it, the second is the reaction time. Different controllers react differently to these parameters. If the mass air flow sensor slightly underestimates or overestimates its readings, then, for example, the “January-5.1” controller, using an oxygen sensor, will be able to track this error and adjust the injection duration. The Bosch MP7.0 controller reacts more sensitively to this error, which leads to unstable idle speed. If the controller does not have an oxygen sensor in feedback, then you can compensate for this error by adjusting the injection coefficient. This will help solve the problem only for a while.
If the mass air flow sensor has a long reaction time, then the “January-5.1” controller will not be able to track the beginning of a change in the amount of air flow during the operation of the machine, and this will be expressed as a “failure” at the time of acceleration. With the Bosh MP7.0 controller, this effect will be less pronounced, due to the presence of a sensor adaptation program in it.
One of the methods for diagnosing a mass air flow sensor is to check the sensor at idle speed and in the mode of a sharp increase in speed when the car is stationary. The sensor is usually controlled by a scanner. A working sensor at idle should show 8-9 kg/h and with a sharp increase in speed the maximum values ​​should be more than 220 kg. The higher the readings the sensor gives, the better.

The disadvantage of this method is the fact that the diagnostician must press the gas pedal quite sharply, which requires some skill. With a smooth increase in speed, the sensor reaches normal readings, but at the same time remains faulty. It turned out that for BOSCH sensors, there is a direct relationship between response speed and time transition process when power is supplied to the sensor itself. Also, the voltage after the transient process indicates a deviation of the readings of the passed air from the norm. For working sensor these parameters should be 2-20ms during the transient process and *1.03V after it. Moreover, than less time transition process - so much the better. Any deviation from 1.03V up or down is a deviation from the norm.

Note: * 1.03V - this voltage will be if the measurement is made relative to the car battery. A more correct measurement is relative to the sensor ground. In this case, the device will show 1V. But this method is less convenient to connect, therefore, the measurement is usually carried out relative to the battery and an appropriate correction is made.

Mass air flow sensor - A capricious sensor - because it is too vulnerable and at the same time practically impossible to diagnose. The method described in the manual (taking readings at idle and 3000 rpm) does not give satisfactory results. In reality, if you suspect a malfunction of the mass air flow sensor, there is only one thing left:

Act at random - see what changes when installing a known-good mass air flow sensor.

The car started to stall all the time??? It is clear that with such behavior, the mass air flow sensor is most likely to blame. For this purpose, without hesitation, you need to find and install a new sensor.

1) The mass air flow sensor still cannot be diagnosed using homespun methods: (Diagnosis of “CE” when the mass air flow sensor fails is the exception rather than the rule.

2) I am increasingly convinced that the problem often discussed here: the engine stalls is in many cases caused by a malfunction of the mass air flow sensor.

3) The mass air flow sensor must be protected. The main enemy is air past the filter; in this case, the air flow sensor lives a maximum of 2..5 thousand km. To avoid this, it is necessary to eliminate leaks between the filter housing and the mass air flow sensor. Leaks are also possible due to the crooked location of the filter itself inside the housing. Well, of course, the quality of the filter is important. If everything is fine with air leaks, then it is believed that it gives correct readings for about 20 thousand km. After which it begins to lie - the dynamics deteriorate, consumption increases, and starting is difficult. The second enemy is crankcase gases reaching the mass air flow sensor.

I will be glad if these thoughts of mine allow someone to save time, nerves and money.

The mass air flow sensor is diagnosed very simply: you insert a pin between the rubber seal and the yellow wire in the mass air flow sensor contact and measure the voltage. Ideally - 0.99V. Well, plus an error of +-0.04V. If the voltage is more than 1.03, the mass air flow sensor is dead.

How does the controller itself diagnose the mass air flow sensor? In other words, a dead mass air flow sensor will miraculously be detected by the controller on its own. Moreover, it will do it better: you can measure the voltage with the device once, but the controller does this (conditionally) constantly, so it is able to “catch” short-term chatter, loss of contact, etc.
Fully faulty air flow sensor easy to diagnose: by measuring voltage, taking readings with a diagnostic device, etc. The trouble is that a completely faulty mass air flow sensor - very rare. SOMETIMES it causes the "CE" diagnostic, basically the car does not drive and does not start well.
In real life, a faulty air flow sensor accessible ways most often goes undiagnosed.

A modern car embodies a bundle of engineering thought. Each unit in it is equipped with sensors that read information and send it to the electronic control unit. The ECU controls all car systems, thereby ensuring its smooth and efficient operation.

Sensors monitor the temperature of the coolant, engine oil pressure, throttle position, the amount of air supplied to the engine combustion chambers and many other parameters of the vehicle's operating systems. The performance of the car depends on the serviceability of these small devices.

Among the sensors, the serviceability of which motorists should pay close attention to, the mass air flow sensor occupies a special place. What is a DMRV? MAF is a mass air flow sensor (in English terminology Mass Air Flow Sensor or MAF), the purpose of which is to determine the amount of air entering the engine. It is used on vehicles with fuel injection and can be used in conjunction with sensors that detect air temperature and atmospheric pressure.

The photo shows the mass air flow sensor. It is always located at the outlet of the air filter

As already mentioned, the main task of the mass air flow sensor is to inform about how much air is currently passing into the combustion chambers of the car’s power unit. This information is important because, unlike a carburetor engine, in which the working mixture is created by the carburetor, an injection engine creates the mixture in the cylinders. The air in the injector is sucked into the cylinders by vacuum, and gasoline is injected by injectors.

Each injection is strictly dosed, and the supply of fuel is controlled electronically based on information received from the sensors. The fuel dose depends on the position of the crankshaft, the speed at which it rotates, the throttle position, and the amount of air entering the cylinders. The DMVR sensor helps the ECU balance the fuel mixture and thereby ensure optimal engine operation under given conditions.

How does the mass air flow sensor work?

Air, as a component of the combustible mixture, enters the cylinders through the air filter through the pipe. The mass air flow sensor is mounted in the air filter housing and connected to the pipe. The connections are sealed, air leakage is not allowed, thanks to this the sensor can accurately determine the amount of air that comes out after cleaning with the filter and transmit information to the electronics unit.

Internal structure of the mass air flow sensor used in the Ford Windstar

Mass air flow sensors installed on cars come in several types:

• The first sensors (air flow meters) were based on the principle of changing the resistance of a resistor under the influence of a bent plate. The blade plate is fixed in the flow meter body and bends under the air flow - the more powerful the flow, the greater the bend. The changing resistance of the resistor signals the car's control unit about the amount of air entering the engine.
• The most common flow meters today are based on the operation of hot-wire meters. Two thin platinum threads are built into the sensor body: one is working, and the other is control. Both threads are heated by current and have the same temperature. The working thread is blown by a stream of air and to maintain the temperature on it equal to the temperature on the control thread, the automation increases the current passing through the working thread. The difference in the current passing through the working thread determines the amount of air sucked in by the engine.
• In new generation air flow meters, silicon plates coated with platinum are used as meters.

Signs of a DMRV malfunction

Check engine - may indicate problems with the mass air flow sensor

Correct data from the mass air flow sensor provides the engine with constant effective mixture formation, and the slightest deviation in the operation of the device immediately affects the power and driving characteristics of the engine. A sensor failure may make it impossible to start the engine.

On a car may occur in the following situations:

• difficult to start the engine;
• The “Check engine” light came on;
• gasoline consumption has increased;
• the speed gain dynamics have worsened;
• The idle speed fluctuates.

The same manifestations may also indicate a breakdown of other devices on the car, so you need to contact a service station and conduct an inspection of the condition of the sensor.

How to check the mass air flow sensor

Disabling the mass air flow sensor

You can try to determine the malfunction of the mass air flow sensor yourself. There are several ways to carry out routine maintenance for this purpose.

• With the engine running, disconnect the block with wires from the sensor. The ECU will power the engine based on the readings coming from the throttle sensor. The engine speed will increase. Then you need to carry out a test drive - improvement in the performance of the power unit will indicate a malfunction of the mass air flow sensor.
• Using a voltmeter, check the voltage between the “sensor signal” and “ground” wires. With the ignition on (the engine is not running), the voltage on the voltmeter should be in the range of 0.9-1.4 volts. Increased voltage indicates a problem sensor.
• You can try to clean the insides of the sensor from dirt by using an aerosol for this purpose, which is used to wash the carburetor.

Modern flow meters are complex and unrepairable devices, so you won’t be able to fix them yourself if they break down. Correct operation of the engine can be restored if the mass air flow sensor is damaged only by replacing it.

To prepare an optimal combustible mixture of gasoline and air, you need to ensure a certain ratio under different engine operating conditions. Only with precise dosing of the amount of gasoline and air can the normal operation of the catalyst be ensured. Therefore, if the flow meter malfunctions, the engine will not work normally.
Purpose, design
An air flow meter or mass air flow sensor is a device that measures the amount of air entering the engine cylinders. There are several varieties of them, which differ in the method of measurement. An earlier design is a pitot tube flowmeter (called a vane type). The principle of its operation is based on measuring the deflection of a special plate by the air flow, on the axis of which a potentiometer is installed. The device resembles a throttle valve. Depending on the speed of the air flow, the angle of rotation of the plate changes, and accordingly, the electrical resistance of the potentiometer.
More modern designs flow meters have a hot-wire air flow meter. The principle of its operation is as follows. In the air flow there is a heat exchange element in the form of a platinum wire. The stronger the air flow, the more electricity must be supplied to it in order to maintain a given temperature difference between the wire and the air flowing around it. To remove deposits on a platinum wire (diameter approximately 0.07 mm), a self-cleaning mode is provided, in which, after stopping the engine, which has been running for some time under load, it is briefly heated to a temperature of 1000–1100 ° C.
The most modern flow meters are hot-wire anemometers with a film meter. Their heating and measuring resistors are made in the form of thin platinum layers deposited on the surface of a silicon crystal.
Flow meters with vortex-type meters are also available. The principle of their operation is based on measuring the frequency of vortices that appear at a certain distance behind the protrusion in the wall of the intake channel. It is worth noting that many modern foreign cars use an absolute pressure sensor in the intake manifold instead of an air flow meter.
Types and causes of malfunctions
Each flowmeter design has its own characteristic faults. For “blade” type flowmeters, this is wear of the current-carrying surfaces of the potentiometers and the formation of oily deposits on the working elements. Wear of the potentiometer (“cut” of the current-carrying path) leads to periodic loss of the electrical signal, as a result, the transmission of distorted data to the control unit. Oily deposits and oxide on the surface of the channel interfere with the movement of the valve (it jams). In the case of hot-wire flowmeters, the cause of the malfunction may be the lack of power supply from the vehicle’s on-board network, as well as unqualified maintenance of this unit. Even attempts to wipe its working surfaces with cotton can damage the flow meter. This unit is not serviceable and cannot be repaired. You can only check the reliability of the contact connections, and in case of contamination, blowing with compressed air or washing the working surfaces with special preparations can help.
Symptoms of a problem
1.Unstable engine idling
2. Deterioration of acceleration dynamics, failures during acceleration
3.Low or high idle speed
4.Increased gasoline consumption
5.The engine does not start
Diagnostics
Except external signs During engine operation, a faulty air flow meter can be reported by the built-in diagnostic system. Unfortunately, without diagnostic equipment, it is not always possible to read error codes and determine why the Check Engine warning light is screaming, so you need to contact a service station. You can verify that the air flow meter is faulty by replacing it with a known good one. If the result is an improvement - the reason is in the flow meter, there is no improvement - you need to look in a different direction. Very often to similar external manifestations causes air leaks through connections or cracks in the corrugated hose running from the flow meter to the throttle module.
Repair methods
Most often they simply replace faulty flow meter new. Only flowmeters with a pitot tube (“blade” type) are repairable. Dirt and oily deposits that interfere with the movement of the plate are removed using carburetor cleaning aerosols. Sometimes it is possible to restore the functionality of the potentiometer by moving its board with the contact track or bending the current collector plates so that the contact tip moves along the unworn part of the contact track. Sometimes technicians suggest disconnecting the flow meter from the electronic control unit. But in this case, fuel consumption increases noticeably. Hot-wire flow meters cannot be repaired in a car service center.
Extending the resource
In order for the air flow meter to last longer, there are two means - change the air filter in a timely manner and monitor the technical condition of the engine (in some old power systems, where the crankcase gas suction hose “cuts in” in front of the air flow meter). Engine repairs can also prevent premature failure of the flow meter, since wear of the piston rings and valve seals leads to an increase in the oil content in the crankcase gases, and this, in turn, causes clogging of the flow meter parts with an oily coating.