Car air volume sensor. What is a mass air flow sensor

When the sensor fails mass flow air, the operation of the injection system will be disrupted, and hence the functioning of the engine of the machine as a whole. If there are signs of a malfunction of the DMRV, the easiest way to diagnose is to install a known working device instead of the controller.

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What is DMRV and its purpose

In a car, this controller is a device used to estimate the amount of air that enters the engine. The sensor belongs to the class of regulators of the electronic control mechanism of the power unit. The first thing that the DMRV affects is the operation of the injection system. The device is designed to determine and regulate air flow, which enters the engine cylinders in order to form a combustible mixture. The controller in a car can be used in conjunction with air pressure and temperature level sensors, which are used to change its readings.

Where is he located?

The regulator can be seen under the hood. Regardless of the model vehicle, the sensor is installed in the intake tract, after the air filter device. The controller is fixed on the air duct.

The channel "In Sandro's Garage" talked about diagnostics, as well as the location of flow meters in VAZ cars.

Principle of operation

The principle of operation of the DMRV can be based on counting Kraman vortices or shifting the potentiometer slider by means of a blade mounted on the air supply stream.

The first option is considered more reliable, since it is not equipped with moving structural elements. In this case, the device counts the Kraman vortices that appear in the laminar air flow. On the way of the latter, special obstacles with sharp edges are used as resistance. The air flow breaks down from them, which linearly depends on its speed. This type of controller only works if there is turbulence in the air.

The StarsAuto channel spoke about the design features, as well as the principle of operation of automotive flow meters.

If the sensor is equipped with a measuring potentiometer, then it functions according to the slider displacement principle. Its working blade is equipped with a spring and is installed in the flow of air consumed by the motor. If it increases, there is a proportional displacement of the blade. The flow has a pulsating character, respectively, to reduce the effect of pulsations, the controller blade is connected to a damper. A potentiometer slider is also associated with it, which, when the sensor is operating, is shifted to a level proportional to the volume of air flow.

This structural element is carried out on ceramic surface where the resistor elements of the voltage divider are installed. Their conclusions are arranged in a row and covered with a special resistive layer. The slider of the device is pressed against the contact component. Due to this, the voltage level on it corresponds to the value at the point of contact with the resistive layer. If the blade changes its position, the elements move, which leads to abrasion of the slider.

DMRV design

Structurally, the mass air flow sensor includes six elements:

• working board of the device;
• plastic case;
• radiator element;
• sensitive component in the form of a wire or a nickel network;
• a pipe through which the air flow passes;
• meshes at the outlet and inlet of the device.

The sensitive component must be supplied with current, otherwise it will not be able to heat up. During operation of the device, the average temperature of the thread should be 75-100 degrees.

Photo gallery "Design DMRV"

Filament device with circuit board inside Film flow meter for cars

The most popular malfunctions of the DMRV

The main signs of a malfunction of the DMRV:

1. Flow meter malfunctions can be reported by the Check Engine indicator, which appears on dashboard inside the car.
2. Depending on the type of device and machine, an icon may appear on the control panel, indicating a low signal level of the MAF.
3. The power unit began to work intermittently. When the sensor is disconnected, the car stalls or the engine speed starts to jump up or down. The power of the internal combustion engine is reduced, the car hardly takes acceleration, especially moving uphill.
4. Increased fuel consumption.
5. When changing gears on the gearbox, the engine randomly stops.

A faulty sensor can be identified by the integrity of the case. The presence of damage on it, as well as on the corrugated line, may indicate a malfunction in the controller. This is a pipe that connects the regulator to the throttle valve. If the engine randomly stalls during operation, this may indicate a malfunction in the power line.

If the air quantity and distribution control device is faulty, then the symptoms of a breakdown may be similar to errors in the operation of the air filter.

Reasons why the device fails:

• the sensor is not connected to the power supply of the machine;
• breakage or damage to the power circuit;
• malfunctions in the operation of the controller may result in malfunctions in the operation of the engine control unit;
• incorrect connection of signal cables or their breakage;
• oxidation or damage to contact elements.

Diagnosis of DMRV

If there is no similar sensor, then there are other ways to check the operability of the flowmeter:

• visual diagnostics;
• checking while driving;
• determination of firmware compliance;
• tester diagnostics.

visual inspection

Before checking the device with this method, it must be dismantled from seat. To do this, the pipes are disconnected from the air filter element housing. Inside the controller must be dry, traces of motor fluid and condensate are not allowed. Often the device breaks down due to non-observance of the air filter change intervals, as a result of which dirt remains on the sensitive component. This causes the controller to give incorrect readings.

If there are traces of motor fluid on the internal cavity of the controller, this indicates high level lubrication pressure in the power unit. The reason may be clogging of the crankcase ventilation. When checking, make sure that the sealing element is located in the right place where the corrugation is installed. This part could be stuck in the air filter housing. With this problem, air is sucked into the engine, which gets inside with dust and contaminates the regulator.

Diagnostics on the move

It is necessary to disconnect the plug with the power circuit from the sensor and start the engine, and then disconnect the block. The Check Engine indicator will appear on the dashboard. The minimum engine speed should increase to 1500 per minute. If the engine began to work more stably after turning off the device, this indicates a malfunction. The sensor needs to be replaced.

User Igor Belov spoke about several methods for diagnosing the flow meter, including checking while driving.

Compliance of the DMRV with the ECU firmware

To check the compliance of the firmware, you need to take a plate 1 mm thick and bring it under the damper stop, this will lead to a change in engine speed. Then the block with wires is disconnected from the controller. If the engine of the machine did not stop, then the reason is the firmware of the microprocessor module, the regulator idling without a flow meter in emergency mode.

Checking the MAF with a multimeter

For diagnostics, the ignition is activated, but the power unit does not need to be started. The contact of the red probe on the tester must be touched to the first cable (yellow), and the black one goes to ground (green contact). For connection, the use of sharp objects is not recommended, as this will lead to an error in the readings. This diagnostic method will determine the voltage level between the conductors.

The status of the sensor will allow you to find out the readings:

• from 0.99 to 1.01 V - parameters of the new controller;
• 1.01 - 1.02 V - the regulator is in excellent condition, no need to change;
• 1.02 - 1.03 V - generally satisfactory condition of the device;
• 1.03 - 1.04 V - the life of the controller is almost exhausted, replacement will soon be required;
• 1.04 - 1.05 V - unsatisfactory condition of the sensor, it's time to change the device.

Tester diagnostics may not be performed on all types of flowmeters. The pre-diagnostic mode of the multimeter must be set to measure the DC current and set the maximum parameter to 2 V. Four cables are connected to the controller, each of which is indicated by a certain color.

Starting from the nearest conductor to the windshield:

• the yellow contact is for flowmeter pulse input;
• white or gray cable is used as the output channel of the supply voltage;
• green contact is ground or ground;
• a black cable equipped with a pink stripe is responsible for the output to the main relay.

The colors of the contacts on the DMRV may be different, but the location of the wires is always identical.

The Simple Opinion channel talked about the flow meter diagnostics using a tester.

What to do with a low signal level of the MAF?

With such a problem, diagnostics are performed:

• the presence or absence of supply voltage, as well as the reliability of connecting the device to ground;
• the resistance level between the contact element 5 (in the diagram) of the connector and ground, this figure should be from 4 to 6 kOhm.

The problem may be:

• poor quality contact;
• wrong route of the harness with wiring;
• wear or damage to the cable core or insulating layer;
• poor connection of the device to ground;
• connecting more powerful energy consumers to the block.

Device diagnostics includes the following steps:

1. The quality of the contact between terminals 7 and 12 on the connector of the injection system, as well as the sensor is checked. A visual check is made of the condition of the block for proper connection. The problem may be damage to the locks or the use of damaged contact elements. Maybe poor quality connecting the conductor to the block.
2. You need to make sure that the harness route is not broken. Problems can arise if the cable bundle is laid next to high voltage wires.
3. The integrity of the harness is checked, no damage is allowed on it. If the element is visually intact, you should try to move it and at the same time monitor the readings of the diagnostic equipment.
4. The clogging of the air filter device is also checked. If required, it is replaced.

If you have a tester, you can check the health of the mass air flow sensor as follows:

1. The key in the lock scrolls to turn off the ignition. It is necessary to disconnect the connector with wires from the controller.
2. Then the ignition is turned on, but the power unit does not start.
3. Using the tester, the voltage level between the contact elements on the connector is diagnosed. Between outputs 2 and 3, this value should be above 10 volts, between 3 and 4 - 5 V, and between ground and the third contact - 0 V. If the obtained indicators are different, you need to eliminate breaks in the line and get rid of a short to ground.
4. The car's ignition is then switched off. Using a multimeter, the resistance level between the fifth pin and ground on the block is diagnosed.

Scheme of connecting the flowmeter to the microprocessor

If the value obtained is about 4.6 kΩ, then the regulator itself is faulty. The problem may lie in its poor-quality connection. At a resistance level of 0 ohms, the problem is a fourth contact shorted to ground or a sensor malfunction. If the value obtained was more than 100 kOhm, this indicates a break in the 4G wire or a breakdown in the regulator.

What to do with a high level of the DMRV signal?

With this problem, it is also necessary to check the presence of voltage on the power circuit and the quality of the connection of the sensor to ground. The parameter is also diagnosed on the fifth contact of the connector.

The check is done like this:

1. The ignition is turned off. Disconnect the connector with wires from the device.
2. The ignition turns on, the engine does not start.
3. Using a multimeter, the voltage on the block is diagnosed. The readings obtained should be the same as when the sensor signal was low.
4. Then the resistance is measured, the tester must first be set to the appropriate mode. The measurement is carried out between the fifth contact element and earth. If the value obtained is 0 V, then the regulator is defective and must be replaced. Other parameters will indicate the short circuit of the 4G conductor to the power source.

How to clean the sensor yourself?

By cleaning and flushing the air flow controller, you can restore its operation.

In particular, you will have to work with the sensitive element of the sensor - this part always gets dirty during the operation of the flowmeter.

Choice of purifier

To complete the task, you must purchase a cleaning agent:

1. Liquid Moly. The mass air flow sensor cleaner of this brand is not cheap. But its use allows you to effectively remove contaminants and restore the operation of the device. The use of Liquid Moli cleaning agents can be carried out on DMRVs running on gasoline or diesel internal combustion engines.
2. Technical or medical alcohol. This option is one of the oldest and most effective. Chemical properties alcohol allow you to qualitatively remove dirt from the sensitive part of the sensor.
3. Carburetor engine cleaner. One of the most affordable and effective ways restore the controller.
4. Means Liquid key. It is allowed to be used not only on the DMRV, but also for the purpose of cleaning other components and mechanisms.
5. WD-40. Allows you to remove not only dirt, but also traces of rust.

Step-by-step instruction

Do-it-yourself mass air flow sensor repair is carried out as follows:

1. Before removing the sensor, turn off the ignition and disconnect the terminal from the battery. In the engine compartment, the connector is dismantled from the flow meter.
2. A pipe is connected to the device, it is also loosened and disconnected. Using a wrench, a bolt is unscrewed that fixes the mechanism on the air filter, in particular, on its housing.
3. The device is removed from the corrugation. Depending on the car model, this may require different instruments, including asterisk keys. The self-tapping screws fixing the device are unscrewed, and then the flow meter is removed from the landing site.
4. If there are traces of oil on the device, they must be removed. To clean up, use one of the above tools.
5. The sensors themselves on the flow meter are usually made in the form of a wire located on a grid. Using a cleaner, it is necessary to carefully process the sensitive component. Film cannot be damaged. When the place of contamination is cleaned, it is necessary to wait about 10 minutes for the product to work.
6. If there is too much dirt on the device, it is advisable to repeat the cleaning procedure several times. To ensure rapid evaporation of the product, you can use a compressor or pump. But too high pressure can lead to the destruction of the sensitive element of the flowmeter.

Photo gallery

Removing the sensor and replacing it

The service life of the device is affected by the purity of the air flow that passes through it. Therefore, when using a flowmeter, it is necessary to prevent the formation of deposits on it. working surface. To do this, it is recommended to periodically check the functioning of the air filter device. If necessary, the sensor must be changed regularly. If the car is operated in a large and polluted city, then the part must be replaced more often than indicated in the car maintenance regulations.

The operating mode of the internal combustion engine is determined by many factors - the load on the engine, the condition of the road, the load of the car, etc. motor to work in optimal conditions a strictly defined ratio of gasoline and air is required. The amount of the latter is determined by the DMRV (mass air flow sensor), it is under it that the engine control controller calculates how much gasoline is needed. A sensor malfunction disrupts the operation of the motor, and often the problem arises of how to check the DMRV in order to establish a final diagnosis.

DMRV malfunction, symptoms

The fact that a DMRV check is needed can be determined by outward signs engine operation. Symptoms indicating that at least the performance of the mass air flow sensor needs to be checked are as follows:

• the Check Engine banner appears on the instrument panel;
• increases the consumption of gasoline;
• the dynamics disappear when the car is moving, the car “dulls”;
• hot engine does not start;
• motor power is lost.

The described symptoms of a malfunction of the DMRV are not exhaustive. All violations in the modes of normal engine operation may be evidence that the DMRV needs to be checked.

What can cause a malfunction of the mass air flow sensor

When the introduction of injection into almost all cars has passed, the presence of a DMRV in them can be considered mandatory. According to various estimates, today there are more than fifty various types mass air flow sensor. Each of them uses its own measurement principle, especially since there are variety of options methods for measuring mass air flow.

It should be noted that all of them are based on the operation of sensitive elements and sensors, which are often quite complex and designed to work under certain conditions. Therefore, a change in these conditions, the appearance of additional factors, such as dirt on the sensing elements that enter with the air flow, causes, if not a malfunction, then at least distorts the DMRV readings.

This is evidenced by the state inner surface air duct and air filter. Often oil gets there through crankcase ventilationcausing malfunctions of the sensor. Therefore, if the DMRV diagnostics shows its malfunction, then sometimes it is enough to clean and flush the sensor to restore its performance.

How to determine the malfunction of the DMRV

Checking the DMRV, which allows you to determine its malfunction, can be performed in several different ways.

To do this, the multimeter control panel is set to measure the DC voltage at the limit of two volts. In the sensor connector, connect to the yellow and green wires. These will be the first and third pins of the connector (windshield side). The colors of the wires may be different, but the numbering of the contacts will be the same.

The ignition is turned on, but the engine does not start, and the DMRV readings are checked. The new sensor has a voltage of (0.996-1.01) V. The larger its value, the worse the state of the MAF. Exceeding the voltage of (1.03-1.04) V indicates that the sensor is in a dying state, and the voltage is greater than 1.05 V, which means that it is time to throw away the mass air flow sensor and install a new one.

The video shows in detail how to check the sensor. It should be noted that in some models, the on-board computer generates voltage at its output.

Cleaning the Mass Air Flow Sensor

The DMRV is not repaired, but it can be cleaned. This is done by flushing the sensor. The attitude to this procedure is far from unambiguous, according to some, such cleaning only kills the sensor, others argue that flushing allows you to restore its performance. In any case, there is ample evidence that properly performed cleaning allows you to operate the DMRV further and avoid costly replacement.

Most likely, everything is determined design features sensor and correct execution works. In any case, when cleaning is carried out, you can not use:

1. ethers;
2. compressed air;
3. cotton buds;
4. acetone.

Again, according to various reviews, carburetor cleaning fluid or WD 40 is used for these purposes. How cleaning is carried out is shown in the video

The DMRV is an integral part of a modern car, and the operational parameters of your car largely depend on it. You can check its performance in several ways, including using an external multimeter. This makes it possible to accurately estimate Current state and take the necessary action.

In order for the engine to work confidently in any mode, it is necessary that it receives the optimal composition of the combustible mixture. As you know, only one engine is not enough fuel, it also needs air. In different modes of engine operation, a different ratio of oxygen and gasoline is required. The air flow meter is responsible for this.

What it is?

This He determines the amount of oxygen that is necessary to fill the cylinders of a car engine under various operating conditions. This device is installed in the intake tract. You can find it after the air filter, in the intake pipe, or on the body of the filter element itself.

In the operation of the injection system, this is the main system.

How the device works

This sensor is necessary, as already mentioned, to measure the ideal amount of oxygen that enters the engine. So, the DMRV is counting right amount and immediately sends this data to the ECU. He does the calculations required amount fuel.

The harder the driver presses the accelerator pedal, the large quantity air enters the combustion chambers power unit. The flow sensor immediately detects this, and then sends a command to the main computer to send more fuel to the cylinders.

If the car moves evenly, then in this mode oxygen is spent in small volumes, which means that fuel consumption will not be large. This is monitored by this same air flow meter.

Device, types of sensors, principles of operation

Together with technical progress the design of these devices is also being improved. At the beginning of the development of the automotive industry, a Pitot tube was used for this purpose. Also, a similar device was called a vane air flow meter. A thin plate was used as the main element. She was softly fastened. The air flow bent the plate. A potentiometer, which was also built into the circuit, could measure how much the plate was bent (resistance was measured). This was the signal for the main control unit.

These devices worked on the same principle on many German cars. So, if you open a BMW air mass meter from the 80s of release, then you can find a sensor with just such a device there. Naturally, on modern cars there are systems with a different device.

Among the most modern and common devices on many cars, plate meters are distinguished. In this device, a heat exchanger with two platinum plates is used as a basic element. The plate is heated by electricity.

One plate is working, and the other is control. The principle of operation of this design is based on maintaining temperatures on each of the plates, while the temperature should be as uniform as possible. These devices can be found on most cars, this technology very popular. Only now, platinum wire is used instead of membranes. The Mercedes air mass meter operates on the same principle.

It works in the following way. When the air flow passes through the heat exchanger, it cools the platinum build plate. To maintain the same temperature on this plate as on the control one, more current is applied to it. The change in current is the data that the ECU needs.

Another air flow meter is a device with film meters. The working elements here are platinum-coated silicon plates. This technology is used recently, so these designs are not yet very common.

There are also devices with vortex meters. Their work is based on measuring the frequencies of swirls that are created at some distance behind the protrusion in the intake valve.

The most modern design- membrane type flow meter. Here, a very thin membrane is applied, which is placed on one side and the other side is installed. When the car is moving, the sides cannot be cooled evenly. The temperature difference is then sent to the ECU for further calculations.

In modern foreign cars, such a sensor may not be available at all; an absolute pressure system is used instead.

Symptoms

There is nothing eternal in a car, the air flow meter sensor also fails, and regularly. Many motorists discuss this problem on the forums.

How can you find out what it is important device start fails? Very simple. The indicators that this element measures are very important in the process of proper preparation of the working mixture of fuel and air. Malfunctions of the DMRV lead to serious disruptions in the operation of the motor, or even the engine cannot be started at all.

If the flow meter fails, a lamp on the dashboard may come on, prompting you to check the engine. Also, malfunctions entail increased fuel consumption, a sharp decline in the power of the power unit. For example, when an Audi air flow meter fails, this is also accompanied by a decrease in the dynamic characteristics of a German car, it becomes very difficult to start the engine, there is no speed stability in the mode.

An experienced motorist will say that these are standard signs that may not be related to the DMRV in any way. Yes it is. But the first thing to check for such symptoms is the DMRV.

How to check the air mass meter

Modern diagnostic practice involves the use of several methods of verification.

The first method - you just need to turn off the power to the sensor. To do this, simply disconnect the connector and start the engine. After that, the ECU will notify you of serious problems. Fuel will continue to be supplied, but with the help of

Diagnostics with a tester

The second method involves the use of a multimeter. Before you start testing, you must remember that the method is not relevant for all sensors. Only a Bosch air mass meter can be tested in this way.

The first step is to set the tester to 2 V and put it in constant voltage mode. The diagram from Bosch clearly states that the MAF must have four wires. So, a signal is given through the yellow wire, gray-white - voltage, green - this is the ground, pink-black is powered along with the main relay.

Now the red tester probe must be connected to the yellow wire. The black probe connects to the green wire. The engine must be turned off before these measurements, but the ignition does not need to be turned off. Next, the voltage is measured.

If the element is in working condition, then the tester will show 101-102. Valid readings are 102-103. This is the upper limit at which repair of the air mass meter is required. If the screen of the tester shows 105 or more, then the sensor is broken and needs to be replaced.

visual inspection

The third method involves diagnosis only by external signs. In order to visually diagnose a breakdown, you should very carefully examine the internal cavity of the pipe on which the sensor is attached. This surface should be as clean and dry as possible.

It should be noted that the most common cause, through which the DMRV fails, this is banal dirt that gets into the working area. This often affects the Audi air mass meter.

Filters should be changed regularly to prevent dirt from getting in.

In addition, traces of oil can be seen on the surface of the sensor. This indicates that the engine has exceeded the oil rate or there are problems in ventilation system crankcase.

The next step is to remove the sensor. To perform dismantling, you will need an open-end wrench. Two bolts are unscrewed and the element is removed from the filter housing for oxygen purification.

At the time of dismantling, it is necessary to make sure that the polyurethane seal is present. It is often removed along with the sensor. The ring is necessary to protect the system from airing. If it is not in the pipe or in the sensor, then the reason is the absence of this ring.

If there is no ring, then dirt will enter the cavity of the part, which is not considered acceptable.

Air mass meter repair

In most cases, these devices cannot be repaired. They are simply replaced with a similar or universal one. Only those that apply the Pitot tube principle can be repaired. Contamination often occurs, which can impede the movement of the plate.

You can cope with dirt with the help of special sprays that are used to flush carburetors. In rare cases, you can restore the operation of this variable resistor by installing it on a board with contacts. Sometimes it is possible to cope with this problem simply by bending the plates so that the tip works on the not yet worn part of the site.

Many experts at the service station offer to disconnect the device from the computer unit. However, nothing good will come of it.

Thermal anemometric flowmeters cannot be repaired either. But you can try to cure the Bosch air flow meter.

How to replace the DMRV

If the sensor cannot be repaired, there is only one way out - replacement. Replacing the sensor is very easy.

To do this, turn off the ignition, remove the connector. Then the fastening screws are unscrewed and the intake tract hose, which is connected to the filter housing, is disconnected. Then the sensor can be safely removed, and a new one can be installed instead. Any air mass meter can be replaced according to this instruction. Opel is no exception.

How to extend the resource?

In order for this device to serve faithfully longer, it is necessary to change the air filters in time and constantly monitor technical condition engine. To extend the life of the sensor, you can also repair the engine. Often, too worn piston rings and valve seals can lead to premature death of the MAF.

How to clean the DMRV

It is very important that during cleaning it is forbidden to touch these wires or spirals with your hands. Also, a toothbrush is not suitable for the procedure.

Before checking the air flow meter, it is advisable to remove and wash it thoroughly. Maybe it will simple solution problems, as the contacts are often dirty.

The first step is to remove the sensor. Then it is disassembled.

When everything is done, i.e., the spirals are visible, you can spray a little on the spirals with the help of a carburetor cleaner in the form of a spray. If it is new, and it still has high pressure, then it is better to spray from a short distance, so the coils will not be damaged.

As it turned out, the flow meter is a very important sensor, and with proper maintenance, it will not often fail.

So, we found out what the mass air flow sensor is for.

When engines are running internal combustion, which are equipped with modern cars, the combustion of the fuel-air mixture occurs, for the formation of which, as you might guess from its very name, it is necessary to mix the fuel with air, and in strictly defined proportions. Accordingly, the systems that are responsible for the formation of this substance, at each moment of the operation of the power unit, must accurately “know” the consumption of each of its components. The value of this indicator for one of them helps to determine the mass air flow sensor (DMRV). It should be noted that it is present in the design of only injection motors, and if drivers notice signs of a malfunction of the DMRV, then they should check it and, if necessary, replace it.

What does a mass air flow sensor look like on a car?

This important sensor is located directly behind the engine air filter, or more precisely, just between it and throttle assembly. It is arranged so finely that it allows you to measure with high accuracy the flow rate of only that air that is well cleaned of mechanical impurities.

During operation, the DMRV transmits electronic system engine control signals that are processed and interpreted as the volume of air that is supplied to form the fuel-air mixture. For normal operation power unit, the volume ratio in it of liquid fuel (gasoline, diesel fuel) and air should be close to 1x14. If this proportion is violated, then either a significant loss of engine power occurs, or an excessive consumption of fuel (by the way, these are the main signs of a malfunction of the DMRV). The information received from the sensor that determines the mass air flow helps to avoid this.

The DMRV measures the amount of air that per unit time enters the fuel rail. It transmits this data to the ECU, which instantly calculates the amount of liquid fuel that must be supplied to form the mixture, and gives the appropriate “orders” to the engine devices responsible for this. Thus, if, for example, you press the accelerator pedal, then more air immediately begins to flow in, the DMRV instantly determines this, sends data to the computer, which increases the supply of gasoline or diesel fuel in the appropriate proportion. If the amount of air decreases, then the volume of liquid fuel supply also decreases.

In terms of design, there are three types of such sensors that are actively used:

• Pitot tube based;
• With hot-wire meters;
• With film gauges.

DMRVs built on the basis of the Pitot tube are already considered obsolete and are not used in the newest engine models. They are so-called vane flow meters, the main elements of which are plates connected to potentiometers and softly fixed on the axes. Changing their position under the influence of air flow, they act on a potentiometer, which changes its electrical resistance.

Mass air flow sensors with hot-wire type meters are quite expensive, although they are very effective. They are equipped with special heat exchangers, consisting of two platinum threads, which are heated by passing electric shock. One of them is blown by an air stream, the second remains a control one, and according to the difference in the current passing through them, the ECU calculates the amount of air entering to form the fuel mixture. DMRV with film meters are considered the most modern. According to their principle of operation, they are almost similar to hot-wire anemometers, only they use not platinum filaments, but ceramic elements with platinum coating.

The main symptoms of a malfunction of the mass air flow sensor

A malfunction of the DMRV, as noted above, leads either to over-enrichment or to depletion of the fuel mixture with gasoline or diesel fuel, which negatively affects the operation of the engine and can lead to its serious damage. Most often, DMRV malfunctions are associated with clogging of the air filter: the air is not cleaned well, and the mechanical particles contained in it enter the sensor, which is the cause of its breakdown. It should be noted that mass air flow sensors are non-repairable devices, and if they fail, they have to be replaced with new ones.

Practice shows that the main signs of a malfunction of the DMRV are as follows:

• A Check Engine error appears, which indicates that the signal level of this sensor is very low;
• The engine consumes more fuel than usual;
• The power unit does not start well, its power decreases, it starts to stall;
• The car does not accelerate well;
• The engine runs either at high or low speed.

Of course, all the signs can also appear with other car malfunctions, but in any case, if at least one of them is found, this is a good reason to visit the station. Maintenance. However, you can check the DMRV for malfunctions on your own, without contacting service station specialists.

The mass air flow sensor (MAF) is a part that determines the amount of air flow supplied through air filter. This mechanism is located near the same filter. Despite its small size, this sensor plays a very important role in the car. A failure of the DMRV can adversely affect the operation of the entire engine. Therefore, in order to avoid unpleasant consequences, it is necessary to regularly diagnose this part and, if necessary, repair or replace it.

Symptoms of a malfunctioning DMRV

You can determine that the air flow sensor is faulty by the following symptoms. First, it is reflected in the increased fuel consumption. Secondly, the signs of a malfunction of the DMRV may be a loss of engine power. It is also worth sounding the alarm when the “Check Engine” error appears on Another symptom is a poor start of the engine “hot”.

However, at the same time, it is worth remembering that all of the above signs of a malfunction of the DMRV may indicate other breakdowns. In particular, poor starting of the engine is manifested in a poorly adjusted carburetor. Loss of engine power can be hidden in a dirty filter. The "Check Engine" light appears when a faulty A is often caused by a dirty filter. Therefore, in order to find out whether the car is really “dressed up” because of the air flow sensor, you need to get to it yourself and diagnose it.

The best diagnostic equipment for the MAF will be a motor tester. However, if you don’t have such a tool at home, you can use a conventional voltmeter with a 2 V scale. yellow wire and sealant. Then turn on the ignition and look at the scale. Ideally, the voltage should range from 0.98 to 0.99 volts. A small error of 0.03 V is allowed. If the arrow on the scale shows less than 0.95 or more than 1.03 V, this indicates that the signs of a malfunction have been confirmed. But you don't have to change the sensor right away. We still have a chance to bring him back to life.

So, we unscrew the fastening elements of the block and proceed to the repair. To do this, you need to prepare an aerosol and bend the tube at a right angle, after heating it with a match. Next, we cut the tube so that the jet beats to the side, and the part itself is straight. We introduce the latter to a depth of 9-10 millimeters into the upper channel of the DMRV and clean the resistor. It is strictly forbidden to use cotton swabs in this case. After a few minutes, we repeat everything again. After the part has dried, put it back into the case and measure the voltage with the same voltmeter. If the received data correspond to the above values, the MAF has been successfully repaired. Well, if the arrow drops below 0.95 V, you need to do a complete replacement of the part. No other is given.