Based on the signal from the mass air flow sensor (MAF), the cyclic filling of the cylinder is calculated, which is ultimately converted into the duration of the injector opening pulse.
If it does not work correctly, the car consumes more gasoline than necessary. Such a sensor is installed on the second path, immediately behind the air filter and connected to the electrical system, which is controlled by a six-pin block of wires. There are quite a few different types of mass air flow sensors: mechanical, ultrasonic, hot-wire and some others.
In this case, we will consider the design of the HFM-5 hot-wire sensor from Bosch, which is most often installed on VAZ cars. The sensor's sensitive element is a thin film on which several temperature sensors and a heating resistor are located. In the middle of the film there is a heating area, the degree of heating of which is controlled using a temperature sensor.
On the surface of the film, on the side of the air flow and on the opposite side, two more thermal sensors are located symmetrically, which record the same temperature in the absence of air flow. In the presence of air flow, the first sensor is cooled, and the temperature of the second remains unchanged, due to the heating of the air flow in the heater zone. The differential signal of both sensors is proportional to the mass of passing air.
- 1 – dielectric diaphragm
- H – heating resistor
- SH – Load temperature sensor. resistor
- SL – Air temperature sensor
- S1 and S2 – temperature sensors before and after the heater.
- QLM – air flow mass
- t – temperature
The sensor's electronic circuit converts this signal into a constant voltage proportional to the air mass. This design is called Hot Film (HFM), its advantages include high measurement accuracy and the ability to record reverse air flow, but its disadvantages include low reliability in conditions of contamination and moisture.
To measure the amount of air that enters the engine means to determine the engine load. When the driver presses the gas pedal, the throttle valve opens and the amount of intake air increases. At the same time, we say that the load has increased. When you release the pedal, the load drops. It's quite simple. However, this is only at first glance. If we take into account the fact that in real driving conditions the engine often changes operating modes and the incoming air in the intake system participates in several gas-dynamic processes, then the problem of measuring the air in the system is not so simple.
In older systems (ECU January-4 and GM-ISFI-2S), other hot-wire mass flow sensors were used, the sensitive elements of which were made in the form of threads. Such sensors are called Hot Wire MAF Sensor. The output signal of these sensors was frequency, that is, depending on the air flow, it was not the voltage that changed, but the frequency of the output pulses. The sensors were less accurate and did not allow registering reverse flow, but these shortcomings were offset by very high reliability.
Several types of mass air flow sensors were installed on VAZ cars: GM, BOSCH, SIEMENS and Russian-made. In 1999-2004 Two types of sensors were installed on VAZ cars: 0 280 218-037 and 0 280 218-004. These sensors produce different output voltage (calibration) parameters at the same air flow rate and interchangeability (or rather, replacing 004 with 037) is only possible with the replacement of calibration tables in the firmware. The same applies to the new sensor 116, which has been installed as standard since the beginning of 2005.
The sensor is supplied only assembled, with a code and marked with a green circle.
On some classic cars, together with the January 7.2 ECU, Siemens-VDO sensors (5WK97014. AVTEL) were used:
They differ in calibration (from zero volts) and connection diagram.
VAZ 2110 air sensor pinout diagram
- Yellow (closest to the windshield) - mass air flow sensor signal input;
- Gray-white—sensor supply voltage output;
- Green — sensor grounding output;
- Pink-black - to the main relay.
The wire colors may change, but the pin locations remain the same.
Let’s also add that the mass air flow sensor with endings 004, 037, 116 (for Bosch) and 00, 10, 20 (for Pekar) are different in calibration. You can only change it by flashing it.
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.
Connecting the MAF air sensor VAZ 2112
If the mass air flow sensor is operational, then when the engine is running at 900 rpm, the volume of air used will be at least 10 kg per hour. When the speed increases to 2 thousand, this figure will increase to approximately 20 kg. If the volume of air at such speeds drops, the dynamics of the vehicle will also decrease, and accordingly, this will lead to a decrease in gasoline consumption.
If these indicators increase, this will also contribute to an increase in fuel volume. Deviations of the parameter by 2-3 kg should not be allowed, since in this case the operation of the power unit may be incorrect.
Useful: VAZ-2108 diagram
Is the air flow sensor covered? Don't rush to buy a new one
A new sensor costs from 2 to 3.2 thousand rubles. But before we run to the nearest store or car market, let’s try to bring the old one back to life. This method of resuscitation does not provide a 100% guarantee of restoration of functionality. But it's worth a try.
First, disconnect the negative terminal on the battery. Remove the sensor from the vehicle. Remove it from the air filter housing. Disassemble the device using a Phillips screwdriver. Be careful with platinum threads, do not touch them with your hands or other objects. Clean with carburetor cleaner. Spray the liquid 3-4 times onto the areas indicated by arrows in the photo. Assemble the mass air flow sensor and install it on the car.
Connection diagram for air flow sensor 2114
A common cause of incorrect operation of the mass air flow sensor is the failure of electronic components, which increases the sensor’s response time to changes in air flow. A working sensor monitors changes at a speed of 0.5 ms, and if it breaks down, the response time increases by 20-30 times. The defect is detected only by recording the operation graph with an oscilloscope. Such a sensor cannot be repaired; it must be replaced with a new one.
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.
Checking the air sensor yourself
When a malfunction of the mass air flow sensor occurs, the air-fuel mixture becomes over-rich or lean, which immediately affects the operation of the engine and may ultimately result in engine failure.
Symptoms of a malfunctioning mass air flow sensor:
- Check Engine error appears;
- Increased fuel consumption;
- Doesn't start well when hot;
- The car began to accelerate slowly;
- Engine power lost.
The easiest way to check the mass air flow sensor on a VAZ 2114 is to disconnect the plug. If there is no signal, the engine control unit goes into emergency operation mode, determining the approximate air volume based on the throttle position. At the same time, fuel consumption increases slightly - for the VAZ 2114 it reaches 10-12 liters per 100 km. A characteristic feature is the increase in idle speed to 1500 rpm. But when using a January 7.2 or Bosch M7.9.7 controller, the idle speed does not increase due to the software features.
The normal voltage at the output of the new sensor is 0.996 - 1.01 Volts. During operation, it gradually changes and, as a rule, increases. The greater the value of this voltage, the greater the wear of the mass air flow sensor.
Here is the reference voltage in volts:
- 1.01 – 1.02 – good condition of the sensor.
- 1.02 – 1.03 – not a bad condition.
- 1.03 – 1.04 - the life of the mass air flow sensor is coming to an end.
- 1.04 – 1.05 — emergency condition.
- 1.05 and above - it’s time to replace the mass air flow sensor.
The measurement is made between the yellow and green wires. Voltage values can be displayed on the screen of some on-board computers (menu voltage from sensors, U Mass air flow sensor).
Important: the limits and fluctuations of the output voltage in at least 30% of cases for a faulty sensor will be NORMAL and will not cause the “Check” icon on the panel. That is, voltage measurements are uninformative, but the rate that it will produce in kilograms of air will correspond to the movement not where it actually is, and the ECU will interfere with the mixture based on it - hence the extra consumption!
You need to check the sensor at a service center, preferably with a proprietary scanner, which itself indicates by blinking if there is a imbalance in some parameter (in this case, air flow in kilograms), comparing it with the reference values stored in its memory.
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.
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.
Replacing the sensor - instructions
Using a screwdriver, unscrew the clamp of the air intake corrugation at the sensor outlet, pull it off and carefully inspect the internal surfaces of the sensor itself and the corrugation. These surfaces must be dry and clean; traces of condensation and oil are unacceptable. If the air filter is changed rarely, then dirt getting on the sensitive element of the sensor is the most common cause of its breakdown in VAZ cars.
There may be oil in the mass air flow sensor as a result of an increased oil level in the engine crankcase, or the oil sump of the crankcase ventilation system is clogged.
Next, unscrew the 2 screws of the sensor with a 10mm wrench and remove it from the air filter housing. There should be a rubber sealing ring on its front part (at the entrance edge). It prevents unfiltered air from being sucked into the intake tract through the sensor.
If the ring is out of place and stuck somewhere in the air filter housing, then there will be a thin layer of dust on the inlet mesh of the sensor itself. This is the second reason that destroys the mass air flow sensor ahead of time.
Correct assembly should take place in the following sequence: put a sealing rubber band on the sensor, check the sealing skirt, then insert everything together into the filter housing.
This concludes the visual check of the mass air flow sensor at home. You can check its operation 100% only with the help of special equipment in a car service center. For example, using a technique for assessing the oscillogram when the throttle is sharply opened to the cutoff mode (a motor tester is needed), or assessing the oscillogram when the ignition is turned on.
Resuscitation of a damaged air flow sensor is successful in no more than 5% of cases. In extreme cases, you can rinse with ethereal liquid to clean matrices and optics. It will evaporate without a trace. After making sure that there is no more dust or debris in the device, you can dry it thoroughly and put it back in place. Sometimes after such a simple procedure the device will work.
On most foreign cars, a mass air flow sensor was installed until 2000; subsequent generations of models began to be equipped with a pressure controller. Replacing a non-working sensor is simple and can be done on your own without any problems, you just need to buy a mass air flow sensor that matches the ECU firmware version. Its price is around 3,000 rubles, depending on the manufacturer.
Let's sum it up
As you can see, the VAZ 2110 mass air flow sensor is a fairly important component of the car in the ECM device. This sensor closely interacts with the computer and determines the degree of enrichment of the fuel mixture with air.
It is quite obvious that any malfunction of the sensor will sharply reduce the efficiency of the engine. At the same time, selecting and replacing the sensor is not difficult. The main thing is to choose the right device and follow the instructions above.
We also recommend reading the article on how to replace the cabin filter on a Lada Granta. From this article you will learn when to change the cabin filter on a Grant, as well as how to change the cabin filter on a Grant with your own hands.
Finally, we note that if the sensor is dirty, it is not necessary to immediately resort to replacement. At the initial stage, it is cleaned, as well as the pipes are treated to remove accumulated debris, dust and dirt, and at the same time, all components of the sensor are inspected. However, if there is no positive result, it is necessary to purchase and replace the device.
Cleaning
Quite often you can avoid replacing the mass air flow sensor by simply cleaning this engine element.
You should do the cleaning yourself in this way:
- Remove the pipe from the mass air flow sensor;
- Now remove the sensor from the pipe. Otherwise, high-quality washing will not work;
- To remove the sensor, arm yourself with sprocket keys in advance. Finding such kits is not a problem;
- Unscrew all the fasteners, remove the sensor from the pipe and assess its external condition;
- Often there are traces of oil deposits on the sensor. The purpose of cleaning is to make the device as good as new;
- Carburetor cleaner is often used to clean the air flow sensor;
- Inside the film there are sensors, which are small wires attached to a special resin. These elements must be carefully sprayed with cleaner so as not to damage the devices;
- Wait a while for the surfaces to dry. To speed up the process, use a can of compressed air;
- It is not uncommon to use alcohol instead of carburetor cleaner, which also works quite effectively;
- Proper cleaning of the mass air flow sensor involves treating the pipes from accumulated debris, dirt and dust;
- Having carefully processed all the components of the removed mass air flow sensor, wait until it dries, and then reassemble it. Cleaning is complete.
Spray cleaning
Statistics show that in about 80% of cases, simple cleaning can return the mass air flow sensor to its previous functionality.
Price issue
80% is not 100. Therefore, sometimes you have to change the sensor. And to replace it, you need to buy it.
There are three price categories for air mass flow sensors:
- Cheap. These are predominantly Chinese products, the price of which is up to 1000 rubles. It is strongly not recommended to purchase such regulators;
- Average. These include sensors from AvtoVAZ, domestic and some foreign analogues. These cost from 1500 to 2500 rubles;
- Expensive. High-quality, reliable, imported air flow sensors, the price of which can reach 5.5 thousand rubles. It’s hard to say how rational it is to buy them. But they will definitely last a long time.
When choosing a new mass air flow sensor, focus not only on the price, but also on the manufacturer. Today, the most popular devices are from Siemens and Bosch. Average in price, excellent in quality.
