The mass air flow sensor is a special sensor that monitors the mass air flow of the power plant. Where is this control device located? In the fuel system of the engine, or rather, directly in the intake tract. Experts call it the most important element that ensures proper fuel injection into the engine. This sensor, like any other component, can fail.
This article describes how the mass air flow sensor operates on the VAZ-2115 and the possible problems that arise when it fails. We will also tell you about ways to eliminate them.
Why do you need a mass air flow sensor?
This monitoring device is designed to determine the volume of air entering the combustion chambers of the power unit. As you know, without this the engine, in principle, will not be able to work. The manufacturer installed it near the air filter.
During operation, the engine receives 1 part gasoline and 14 parts air. As a result, the most optimal mixture is formed, allowing the power plant to operate as efficiently as possible.
If this proportion is not respected for one reason or another, the following begins to happen:
- excessive gasoline consumption;
- power drop.
Therefore, correct air mass flow is one of the basic conditions for the proper functioning of the vehicle. This parameter is calculated in the ECU based on the MAF readings.
Depending on how hard the driver of the car presses on the accelerator, the air is supplied more intensely. For its part, the mass air flow sensor measures its incoming volumes, and the data is sent to the on-board computer. The latter regulates the flow of gasoline accordingly.
Mass air flow sensor design
| Position number | Explanation of the position in the figure DMRV VAZ 2114, 2113, 2115 |
| 1 | Frame |
| 2 | Connector |
| 3 | DMRV VAZ 2114, 2113, 2115 |
| 4 | MAF circuit |
| 5 | Metal screen |
| 6 | Air deflector |
| 7 | Inlet air flow |
Operating principle of the air flow sensor
The sensor is based on a platinum wire only 70 micrometers thick. It is hidden in a special tube located in front of the throttle valve. When air hits it, the wire cools. To restore normal temperature, a certain charge of electricity passes through it, according to the size of its ECU, and finds out exactly how much fuel the engine needs at the moment.
Due to the fact that air comes directly from the atmosphere, dirt regularly settles on the wire. It is this that, for the most part, contributes to the fact that the sensor becomes unusable. The latest models of mass air flow sensors, however, have an automatic cleaning system.
A significant drawback of the described design is its inability to repair. As a result, sooner or later, the expense of money becomes inevitable.
Location
The mass air flow sensor works directly with the air supplied to the engine; AvtoVAZ engineers, when designing the VAZ 2115, acted rationally and placed the mass air flow sensor near the air filter, namely behind it. The sensor is attached to the air filter box through two 6 mm bolts, and on the other side, an inlet corrugation is put on the sensor and secured through a clamp.
DMRV failure - how to identify
If this control element fails, a lamp lights up on the dashboard, signaling the need to check the car’s power plant.
The main signs of failure of the mass air flow sensor:
- power is lost;
- the speed also drops;
- a lot of fuel is consumed;
- the engine starts poorly.
There are several ways to determine the performance of the mass air flow sensor:
- by turning off;
- multimeter;
- upon inspection.
In the first case, replacing the sensor is not difficult. Just disconnect the connector (pinout is not required here) and turn on the engine. The ECU must go into emergency mode. In this case, the supply of the combustible mixture is regulated only by the throttle valve. At the same time, at idle, the power unit produces 1.5 thousand revolutions. Next, you will need to drive a certain distance. If the car accelerates faster than usual, we can confidently say that the mass air flow sensor has broken down.
It is also worth pointing out that the multimeter is useful only if the car is equipped with a sensor manufactured by.
The check goes like this:
- The scale on the tester is set to 2 volts of DC voltage;
- the red probe is attached to the yellow wire, the black one to the green;
- turn on the ignition.
If the readings are within:
- 1.02 volts - then the sensor is working;
- 1.03 – acceptable value;
- 1.05 is the limit.
In cases where the measured voltage is higher, a breakdown should be considered. In order to determine from the appearance of the control device whether it is working, you will need to carefully examine the tubes leading to it from the inside. They are easy to dismantle using a Phillips screwdriver. First of all, unscrew the clamp securing the corrugated sleeve. The surface of this tube must be clean, without oily films.
The presence of dirt inside the sensor is a clear sign of its malfunction. As a rule, the problem occurs when the car owner forgets to change the air filter on time.
Oil leaks are usually evidence of excess lubricant in the system or improper operation of the shut-off valve. Such contamination significantly reduces the service life of the mass air flow sensor.
Then it is necessary to dismantle the sensor itself. To do this, you need to use a 10mm socket wrench. After the control device is removed from the filter, it will need to be inspected. In a situation where the rubber gasket of the sensor remains in place, then we can speak with almost one hundred percent certainty about a breakdown of the mass air flow sensor.
How to check the flow meter on a VAZ 2115 yourself
- If the “Check Engine” light comes on on the dashboard, you can determine errors using OBD codes using a car scanner. However, such equipment is not always at hand.
- The initial check can be carried out by simply disconnecting the flow meter connector and comparing the behavior of the engine with and without the mass air flow sensor. After disconnecting a working sensor, the car's behavior should worsen. A broken flow meter when disconnected will not change the operation of the motor.
- And finally, a relatively accurate test using a multimeter. It is carried out in two stages. First, the power supply to the device is checked with the disconnected connector. From the ECU, 12 volts should be supplied to pin 2, and 5 volts to pin 4. Measurements are made relative to weight, with the ignition on and the engine turned off. Then the voltage of the sensor signal is measured at the connected connector in a resting state (ignition on, engine not running). To do this, you need to equip yourself with a relatively accurate multimeter that can measure voltage with an error of up to 1/100 volt.
Regarding ground, there should be a voltage of 0.99 to 1.02 volts at pin No. 5. It is possible to increase the value to 1.05 volts, but this indicates a high degree of wear on the mass air flow sensors.
Cleaning the air flow sensor
As noted earlier, the mass air flow sensor cannot be repaired. But some craftsmen manage to clean it, thus extending the service life of the monitoring device in question. Moreover, some claim that they have done this more than once.
In reality, it is worth recognizing that the chance of repair is quite low. However, if you take into account that the cost of a new sensor is quite high, and an attempt to revive the old one generally requires nothing but time, then you should try.
To clean the air flow sensor you will need:
- composition for cleaning carburetors;
- soft brush;
- Phillips screwdriver.
The sensor is disassembled and the inside of the tube and the platinum wire itself are carefully cleaned. Next, all parts must be left to dry. During this time, remove the throttle entirely and also clean it of any plaque inside. Do not remove the cable from the gas pedal. The assembly is placed on a clean rag and washed with carburetor fluid. You will also need to clean the idle speed regulator and the surrounding area from dirt. If you manage not to damage the wire in the mass air flow sensor, then eventually the problem will become less acute for some time. It is important that the sensor is not damaged mechanically.
Finally, it is worth noting that to increase the service life of the sensor, first of all, it is necessary to replace the air filter on time.
Replacement
Replacing the sensor is quite simple; all you need is a 10 mm wrench and a Phillips screwdriver.
The replacement process is complete, after this procedure your car should drive like new.
Source
What does a faulty air flow sensor cause?
Operating an engine with an inoperative/faulty flow meter causes detonation of the fuel mixture in the combustion chamber. This affects the operation of the crank mechanism (crank mechanism) and destroys the piston surface, which can cause a “wedge” in the engine.
What indications should a working mass air flow sensor give?
The voltage of the analog-to-digital converter (ADC) of the flow meter when the engine is not running should be 0.996 V. Indicators of 1.016 and 1.025 V are acceptable, but if they reach more than 1.035 volts, it means that the sensing element of the mass air flow sensor is clogged.
IT IS IMPORTANT TO KNOW . To accurately determine the degree of deviation of the operating flow meter values from normal values, it is necessary to evaluate the engine operation at different speeds.
For example, for an injection 1.5-liter VAZ 2111 engine, if it is in good condition, at idle (860–920 rpm) the correct readings are 9.5–10 kg/hour, and at 2 thousand rpm - 19 –21 kg/hour. If the flow meter at 2 thousand rpm shows about 17–18 kg, then the car will drive stably. If the values are from 22 to 24 kg/hour, then the vehicle will move steadily, but the fuel consumption per 100 km will be approximately 10–11 liters. In addition, the car will have difficulty starting in cold weather due to fuel overflow when the engine warms up.
Design
The sensor is a cylindrical part made of special plastic that is resistant to high temperatures. The body of the sensor contains a special sensitive element that counts the amount of air entering the combustion chamber of the engine. A special mesh is installed in front of this element, which prevents the entry of large debris that can damage not only the sensor, but also the internal combustion engine itself.
The sensor has a connector for connecting a control circuit with 4 pins. The connector is connected to the sensor on one side, and on the other to the engine control unit.
Symptoms of a problem
The mass air flow sensor is located in the air duct near the air filter. It is designed to determine the amount of incoming air. Depending on its readings, the control unit will show how much fuel is needed to form a high-quality fuel mixture. The normal ratio is 1:14. Therefore, the quality of the fuel-air mixture depends on the correct readings of the flow meter.
The high-quality operation of the mass air flow sensor depends largely on the cleanliness of the air filter. Therefore, if symptoms of a malfunction of the mass air flow sensor appear, you should first check the air filter before making repairs. The flow meter is usually beyond repair. If it is faulty, it is replaced with a new device. But its cost is quite high, so you should first make sure that the causes of the problems are in the sensor and not in other malfunctions of the machine.
The signal for diagnosis is the following symptoms of a malfunction of the mass air flow sensor:
- Check Engine appears on the instrument panel;
- an error is displayed indicating a low level of the mass air flow sensor signal;
- the engine is bad, accelerates very slowly, stalls, its power drops;
- high level of fuel consumption;
- the engine is unstable at idle;
- the engine stalls when changing gears;
- The rpms are either high or low.
There are other symptoms of a “dying” sensor. For example, it may have cracks in the corrugated hose that connects the throttle body to the sensor. If the engine stalls, there may be a power problem or damaged wiring. This is a signal to check the electrical wiring. If malfunctions are detected, the machine's electrical system must be repaired.
In addition to the above possible signs of failure of the mass air flow sensor, you should diagnose the sensor signal level.
A low signal level may mean the following:
- Mass air flow sensor is not connected;
Disconnected sensor connector
- open circuit in the sensor connection circuit;
- the mass in the chain breaks, oxidation appears;
- signal wires are broken or incorrectly connected;
- Engine control unit malfunction.
You should not draw conclusions about a malfunction of the mass air flow sensor, relying only on the symptoms listed above. A complete diagnosis of the engine and machine should be carried out, since signs of a flow meter failure may appear if other devices malfunction (for example, due to a clogged air filter). Then you need to repair these devices to restore the car's functionality.
DMRV error code
The following errors may indicate a malfunction in the operation of the mass air flow sensor:
- P0100 - damage to the electrical circuit connecting the sensor. To eliminate the breakdown, you need to check the wiring for integrity, since accidental disconnection of the connector or damage to the electrical contacts is possible.
- P0102 - the vehicle control unit began to receive a low signal, which was recorded at the input of the mass air flow sensor power line. To eliminate the cause of the breakdown, it is necessary to check the electrical wiring and the insulating layer of the cable; oxidation of the contacts of the wiring connector (the so-called chips) is possible.
- P0103 - critically high signal detected at the input of the mass air flow sensor power line. If the cause of the malfunction is not the wiring, then a visual inspection and cleaning of the flow meter will be required or it will have to be replaced with a new one.
Purpose
The mass air flow sensor is designed to count the air passing through it. To operate an internal combustion engine, you need not only fuel, but also air, and for uniform and stable operation of the internal combustion engine, fuel and air must be mixed strictly within certain parameters to form a fuel-air mixture. The air passing through the sensor is counted by a special sensing element, which transmits these readings to the engine control unit. In turn, the ECU sends signals to the fuel pump and injectors to increase or decrease the fuel supply depending on the amount of air entering the engine, and the air-fuel mixture is formed in the required parameters.
Checking and repairing at home
There are eight ways to independently check amplitude and frequency mass flow sensors.
Method No. 1 - disabling the air flow meter
The method consists of disconnecting the sensor from the fuel system of the car and checking the functionality of the system without it. To do this, you need to disconnect the device from the connector and start the engine. Without a mass air flow sensor, the controller receives a signal to switch to emergency operation mode. It prepares the air-fuel mixture only based on the throttle position. If the car moves faster and does not stall, it means that the device is faulty and requires repair or replacement.
Method No. 2 - flashing the electronic control unit
If the standard firmware has been changed, then it is unknown what reaction of the controller is programmed in it in case of an emergency. In this case, you should try to insert a 1mm thick plate under the throttle stop. The turnover should increase. Now you need to pull out the chip from the air flow meter. If the power unit continues to work, then the cause of the malfunction is the firmware.
Method No. 3 - installing a working sensor
Install a known good part and start the engine. If after replacement it begins to work better, the motor does not stall, then replacement or repair of the device is required.
Method No. 4 - visual inspection
To do this, use a Phillips screwdriver to unscrew the clamp holding the air collector corrugation. Then you need to disconnect the corrugation and inspect the internal surfaces of the air collector corrugation and the sensor.
Inspection of duct corrugation
There should be no traces of oil or condensation on them, the surfaces should be dry and clean. If you do not take care of the air filter and change it rarely, then dirt can get on the sensitive element of the sensor and cause it to break. This is the most common malfunction. Traces of oil may appear in the flow meter if the oil level in the crankcase is high, or if the oil sump of the crankcase ventilation system is clogged. If necessary, you need to clean the surfaces using special cleaning products.
Method No. 5 - checking the mass air flow sensor with a multimeter
To do this, you need to turn on the tester in a mode in which constant voltage is checked. The limit value for measurements should be set to 2V.
DMRV operation diagram
Sensor pinout:
- The yellow wire is located closer to the windshield. It serves as an input for a signal from the flow meter.
- The white-gray wire is the sensor voltage output.
- The black and pink wire leads to the main relay.
- The green wire is used to ground the sensors, that is, it goes to ground.
The wires may have different colors, but their location is unchanged. To check, you need to turn on the ignition, but do not start the car. The red probe from the multimeter must be connected to the yellow wire, and the black one must be connected to ground, that is, to the green wire. We measure the voltage between these two outputs. Multimeter probes make it possible to connect without disturbing the insulation of the wires.
On the new device, the output voltage ranges from 0.996 to 1.01 V.
During operation, this voltage gradually increases and by its value one can judge the wear of the flow meter:
- if the sensor is in good condition, the voltage is from 1.01 to 1.02 V;
- in satisfactory condition - from 1.02 to 1.03 V;
- the sensor resource ends if the voltage is in the range from 1.03 to 1.04 V;
- a value in the range from 1.04 to 1.05 indicates a near-death state; if there are no contraindications, then you can continue to use the sensor;
- if the voltage exceeds 1.05 V, the mass air flow sensor requires replacement.
ADC flow meter readings
Diagnostics of the mass air flow sensor "Tseshkoy" is not difficult and can be done with your own hands.
If there is dirt on the removed sensor, you can clean it yourself. You can use WD-40 to wash it. To clean the mass air flow sensor, you must first remove the pipe from it, and then dismantle the device itself. Inside the device there is a mesh and several wires - sensors.
They need to be sprayed with cleaning agent and washed. Then let the liquid dry. If dirt remains, the procedure should be repeated. You need to clean the pipe with the same product. It must be free of dirt and oil stains. After replacing the air filter, all parts must be returned to their place. After the cleaning procedure, the functionality of the device can be restored to 80%, the error about the reduced sensor signal level disappears (the author of the video is “24 hours”).
Flushing the sensor will help avoid costly repairs.
Method number 6 - checking with a scanner
Test method:
- Install a diagnostic program on your phone (smartphone), tablet or laptop computer (for example, Torque Pro, Opendiag, BMWhat, OBD Auto Doctor).
- Connect your mobile device or laptop to the diagnostic connector located on the vehicle's electronic control unit using a special cable, Bluetooth channel.
- Launch the diagnostic utility on your phone (smartphone) or computer.
- Wait until the program finishes scanning all vehicle components. As a result, the utility will check the serviceability of each vehicle unit.
- Decipher the error codes that the program will show after the diagnostics are completed.
To perform this method, testers are used:
- K-Line 409/1;
- Scanmatic;
- ELM (ELM) 327;
- OP-COM.
Method No. 7 - checking by Vasya the Diagnosticist
To identify a malfunction of the mass air flow sensor without removing it from the car, you need to:
- Install a program called “VASYA diagnostician” on your laptop (laptop) and run it.
- Connect the adapter to the vehicle's diagnostic port.
- Select the item “Electronics 1” or “01 – Engine electronics” from the “Control unit” tabs to connect to the vehicle’s control unit.
- Go to “Custom Groups”.
- Select 211, 212 (passport value) and 213 (current value).
- Compare current indicators with passport data. If the deviations are high, then it is necessary to replace the mass air flow sensor.
Method No. 8 - using a motor tester
GOOD TO KNOW
This method is used to test frequency-type flowmeters.
To check the mass air flow sensor with a motor tester (oscilloscope), you need to connect it to the sensor (depending on the car brand) and start the engine.
Mass air flow sensor check parameters:
- transient time when the ignition is on;
- air consumption readings at idle and a sharp increase in engine speed;
- voltage in the sensor network.
IT IS IMPORTANT TO KNOW
The output data is individual for different types of engines. Before diagnosis, you should check the current indications with an official representative.
