For optimal operation of an injection internal combustion engine (hereinafter referred to as ICE), it is necessary to take into account how much air mixture enters the combustion chambers of the cylinders. Based on these data, the electronic control unit (hereinafter referred to as the ECU) determines the fuel supply conditions. In addition to information from the mass air flow sensor, its pressure and temperature are taken into account. Since mass air flow sensors are the most significant, we will consider their types, design features, diagnostic and replacement capabilities.
Purpose and explanation of the abbreviation
Flow meters, also known as volume meters or mass air flow meters (not to be confused with mass air flow meters and mass air flow sensors), are installed in diesel or gasoline-powered vehicles. The location of this sensor is not difficult to find, since it controls the air supply, you should look for it in the corresponding system, namely, after the air filter, on the way to the throttle valve (DZ).
The device is connected to the engine control unit. In cases where the mass air flow sensor is in a faulty condition or is missing, a rough calculation can be made based on the position of the air flow sensor. But with this measurement method it is impossible to ensure high accuracy, which will immediately lead to excessive fuel consumption. This once again indicates the key role of the flow meter in calculating the fuel mass supplied through the injectors.
In addition to information from the mass air flow sensor, the control unit also processes data coming from the following devices: camshaft sensor (camshaft sensor), DD (knock meter), remote sensor, cooling system temperature sensor, acidity meter (lambda probe), etc.
Types of mass air flow sensors, their design features and operating principle
Three types of VU meters are most widespread:
- Wire or thread.
- Film.
- Volumetric.
In the first two, the operating principle is based on obtaining information about the mass of the air flow by measuring its temperature. The latter may involve two accounting options:
Vortex sensor design (widely used by Mitsubishi Motors) Designations:
- A – pressure measurement sensor to record the passage of the vortex. That is, the frequency of pressure and vortex formation will be the same, which makes it possible to measure the flow of the air mixture. At the output, using an ADC, the analog signal is converted to digital and transmitted to the ECU.
- B - special tubes that form an air flow similar in properties to laminar.
- C – bypass air ducts.
- D – column with sharp edges on which Karman vortices are formed.
- E – holes used to measure pressure.
- F – direction of air flow.
Wire sensors
Until recently, thread mass air flow sensor was the most common type of sensor installed on domestic cars of the GAZ and VAZ model range. An example of a wire flow meter design is shown below.
Designations:
- A – Electronic board.
- B – Connector for connecting the mass air flow sensor to the computer.
- C – CO adjustment.
- D – Flow meter housing.
- E – Ring.
- F – Platinum wire.
- G – Resistor for temperature compensation.
- N – Ring holder.
- I – Electronic board casing.
Operating principle and example of a functional diagram of a filament VU meter.
Having understood the design of the device, let's move on to the principle of its operation, it is based on the hot-wire method, in which a thermistor (RT), heated by the current passing through it, is placed in the air flow. Under its influence, the heat transfer changes, and, accordingly, the resistance RT, which makes it possible to calculate the volumetric flow rate of the air mixture? using King's equation:
I 2 *R=(K 1 +K 2 * ⎷ Q )*(T 1 -T 2) ,
where I is the current passing through RT and heating it to temperature T1. In this case, T 2 is the ambient temperature, and K 1 and K 2 are constant coefficients.
Based on the above formula, you can derive the volumetric air flow rate:
Q = (1/K 2)*(I 2 *R T /(T 1 – T 2) – K 1)
An example of a functional diagram with bridge connection of thermoelements is shown below.
Designations:
- Q - measured air flow.
- U – signal amplifier.
- R T - wire thermal resistance, as a rule, is made of platinum or tungsten filament, the thickness of which is in the range of 5.0-20.0 microns.
- R R – temperature compensator.
- R 1 -R 3 – ordinary resistances.
When the flow velocity is close to zero, the RT is heated to a certain temperature by the current passing through it, which allows the bridge to be kept in equilibrium. As soon as the flow of the air mixture increases, the thermistor begins to cool, which leads to a change in its internal resistance, and, as a result, an imbalance in the bridge circuit. As a result of this process, a current is generated at the output of the amplifier unit, which partially passes through the temperature compensator, which leads to the release of heat and makes it possible to compensate for its loss from the flow of the air mixture and restores the balance of the bridge.
The described process allows you to calculate the flow rate of the air mixture based on the amount of current passing through the bridge. In order for the signal to be perceived by the ECU, it is converted into a digital or analog format. The first allows you to determine the flow rate by the frequency of the output voltage, the second - by its level.
This implementation has a significant drawback - a high temperature error, so many manufacturers add a thermistor similar to the main one to the design, but do not expose it to air flow.
During operation, dust or dirt deposits may accumulate on the wire thermistor; to prevent this, this element is subjected to short-term high-temperature heating. It is performed after the internal combustion engine is turned off.
Film air meters
A film MAF works on the same principle as a filament one. The main differences lie in the design. In particular, silicon crystal is used instead of platinum filament resistance wire. It is coated with several layers of platinum plating, each of which plays a specific functional role, namely:
- Temperature sensor.
- Thermal resistances (usually there are two of them).
- Heating (compensation) resistor.
This crystal is installed in a protective casing and placed in a special channel through which the air mixture passes. The geometry of the channel is designed in such a way that temperature measurements are taken not only from the input flow, but also from the reflected one. Thanks to the created conditions, a high speed of movement of the air mixture is achieved, which does not contribute to the deposition of dust or dirt on the protective housing of the crystal.
Designations:
- A – Flow meter body into which the measuring device (E) is inserted.
- B – Contacts of the connector that connects to the ECU.
- C – Sensitive element (silicon crystal with several layers of coating, placed in a protective casing).
- D – Electronic controller, with the help of which preliminary processing of signals is carried out.
- E – Body of the measuring device.
- F - Channel configured to take thermal readings from the reflected and input flow.
- G – Measured flow of air mixture.
As mentioned above, the operating principles of filament and film sensors are similar. That is, the sensitive element is initially heated to temperature. The flow of the air mixture cools the thermoelement, which makes it possible to calculate the mass of the air mixture passing through the sensor.
As in filament devices, the output signal can be analog or converted to digital format using an ADC.
It should be noted that the error of filament VU meters is about 1%; for film analogues this parameter is about 4%. However, most manufacturers have switched to film sensors. This is explained both by the lower cost of the latter and by the expanded functionality of the ECUs that process information from these devices. These factors overshadowed the accuracy of the instruments and their speed.
It should be noted that thanks to the development of flash microcontroller manufacturing technology, as well as the introduction of new solutions, it was possible to significantly reduce the error and increase the performance of film structures.
Interchangeability
This issue is quite relevant, especially taking into account the cost of original products from the imported automobile industry. But it’s not so simple here; let’s give an example. In the first production models of the Gorky Automobile Plant, the injection Volgas were equipped with a BOSCH air flow sensor. Somewhat later, imported sensors and controllers replaced domestic products.
A – imported filament air flow sensor manufactured by Bosh (pbt-gf30) and its domestic analogues B – JSCB “Impuls” and C – APZ Structurally, these products were practically no different with the exception of several design features, namely:
- The diameter of the wire used in a wirewound thermistor. Bosch products have a diameter of 0.07 mm, and domestic products have a diameter of 0.10 mm.
- The method of fastening the wire differs in the type of welding. For imported sensors this is resistance welding, for domestic products it is laser welding.
- Shape of a thread thermistor. Bosh has a U-shaped geometry, APZ produces devices with a V-shaped thread, and products from JSC Impulse are distinguished by the square shape of the thread suspension.
All the sensors given as an example were interchangeable until the Gorky Automobile Plant switched to film analogues. The reasons for the transition were described above.
Film air flow sensor Siemens for GAZ 31105 It makes no sense to give a domestic analogue to the sensor shown in the figure, since outwardly it is practically no different.
It should be noted that when switching from filament devices to film devices, most likely, it will be necessary to change the entire system, namely: the sensor itself, the connecting wire from it to the ECU, and, in fact, the controller itself. In some cases, the control can be adapted (reflashed) to work with another sensor. This problem is due to the fact that most filament flowmeters send analog signals, while film flowmeters send digital signals.
It should be noted that the first production VAZ cars with an injection engine were equipped with a filament air flow sensor (made by GM) with a digital output; examples include models 2107, 2109, 2110, etc. Now they are equipped with air flow sensor BOSCH 0 280 218 004 .
To select analogues, you can use information from official sources or thematic forums. As an example, below is a table of the interchangeability of mass air flow sensors for VAZ cars.
The presented table clearly shows that, for example, the MAF sensor 0-280-218-116 is compatible with VAZ 21124 and 21214 engines, but is not suitable for 2114, 2112 (including those with 16 valves). Accordingly, you can find information on other VAZ models (for example, Lada Granta, Kalina, Priora, 21099, 2115, Chevrolet Niva, etc.).
As a rule, there will be no problems with other brands of cars of domestic or joint production (UAZ Patriot ZMZ 409, Daewoo Lanos or Nexia), choosing a replacement mass air flow sensor for them will not be a problem, the same applies to products of the Chinese automobile industry (KIA Ceed, Spectra, Sportage etc.). But in this case, there is a high probability that the MAF pinout may not match; a soldering iron will help correct the situation.
The situation is much more complicated with European, American and Japanese cars. Therefore, if you have a Toyota, Volkswagen Passat, Subaru, Mercedes, Ford Focus, Nissan Premiere P12, Renault Megane or another European, American or Japanese car, before replacing the mass air flow sensor, you need to carefully weigh all the solution options.
If you are interested, you can search online for an epic about an attempt to replace the “native” air meter with an analogue on a Nissan Almera H16. One attempt resulted in excessive fuel consumption even at idle.
In some cases, searching for an analogue one will be justified, especially if you take into account the cost of the “native” VU meter (for example, the BMW E160 or Nissan X-Trail T30).
Functionality check
Before diagnosing the mass air flow sensor, you need to know the symptoms that allow you to determine the degree of performance of the MAF (abbreviation for the English name of the device) sensor in the car. We list the main symptoms of a malfunction:
- The consumption of the fuel mixture has increased significantly, while at the same time acceleration has slowed down.
- The internal combustion engine idles with jerks. In this case, a decrease or increase in speed may be observed in idle mode.
- The engine does not start. Actually, this reason in itself does not mean that the flow meter in the car is faulty; there may be other reasons.
- A message appears about a problem with the engine (Cheeck Engine)
Example of the "Cheeck Engine" message displayed (marked in green) These signs indicate a possible malfunction of the mass air flow sensor; in order to accurately determine the cause of the failure, diagnostics must be performed. It's easy to do it yourself. Connecting a diagnostic adapter to the ECU (if this option is possible) will help to significantly simplify the task, and then determine the serviceability or malfunction of the sensor using the error code. For example, error p0100 indicates a fault in the flow meter circuit.
But if you need to carry out diagnostics on domestic cars manufactured 10 years ago or more, then checking the mass air flow sensor can be carried out in one of the following ways:
- Testing while moving.
- Diagnostics using a multimeter or tester.
- External inspection of the sensor.
- Installation of a similar, known-good device.
Let's consider each of the listed methods.
Testing while driving
The easiest way to check is by analyzing the behavior of the internal combustion engine with the MAF sensor disabled. The algorithm of actions is as follows:
- You need to open the hood, turn off the flow meter, close the hood.
- We start the car, and the internal combustion engine goes into emergency mode. Accordingly, a message indicating a problem with the engine will appear on the dashboard (see Fig. 10). The amount of fuel mixture supplied will depend on the position of the remote control.
- Check the dynamics of the car and compare it with what it was before the sensor was turned off. If the car has become more dynamic and power has also increased, then this most likely indicates that the mass air flow sensor is faulty.
Note that you can continue driving with the device turned off, but this is highly not recommended. Firstly, the consumption of the fuel mixture increases, and secondly, the lack of control over the oxygen regulator leads to increased pollution.
Diagnostics using a multimeter or tester
Signs of a malfunction of the mass air flow sensor can be identified by connecting the black probe to ground, and the red probe to the sensor signal input (the pinout can be found in the device data sheet, the main parameters are also indicated there).
Next, we set the measurement limits to 2.0 V, turn on the ignition and take measurements. If the device does not display anything, you need to check that the probes are connected correctly to ground and the flow meter signal. Based on the readings of the device, you can judge the general condition of the device:
- A voltage of 0.99-1.01 V indicates that the sensor is new and working properly.
- 1.01-1.02 V – used device, but its condition is good.
- 1.02-1.03 V - indicates that the device is still operational.
- 1.03 -1.04 the condition is approaching critical, that is, in the near future it is necessary to replace the mass air flow sensor with a new sensor.
- 1.04-1.05 – the device’s resources are almost exhausted.
- Over 1.05 - a new mass air flow sensor is definitely needed.
That is, you can correctly judge the state of the sensor by the voltage; a low signal level indicates an operational state.
External inspection of the sensor
This diagnostic method is no less effective than the previous ones. All that is necessary is to remove the sensor and assess its condition.
Inspect the sensor for damage and fluid Characteristic signs of a malfunction are mechanical damage and liquid in the device. The latter indicates that the oil supply system to the engine is not adjusted. If the sensor is very dirty, the air filter should be replaced or cleaned.
Installing a similar, known-good device
This method almost always gives a clear answer to the question of the sensor’s performance. This method is quite difficult to implement in practice without purchasing a new device.
Briefly about the renovation
As a rule, MAF sensors that have become unusable cannot be repaired, except in cases where they require washing and cleaning.
In some cases, it is possible to repair the volumetric air flow sensor board, but this process will not prolong the life of the device for long. As for the boards in film sensors, without special equipment (for example, a programmer for a microcontroller), as well as skills and experience, it is pointless to try to restore them.
Many car enthusiasts have encountered the fact that the sensor of a mass-produced VAZ-2114 failed, but not everyone can carry out diagnostic operations with a minimum set of tools. This article will tell you how to diagnose the MVR using a multimeter.
Video of checking the mass air flow sensor on a VAZ-2114 using a multimeter
DMVR device on VAZ-2114
General view of the DMVR sensor
Before proceeding directly to diagnostics, you need to know the design features and structure of this sensor. Let's look at the diagram of the DMVR device in the image.
DMVR device diagram
Causes of sensor malfunction
The next step before diagnosis is to identify the causes of the malfunction, as well as factors that may influence the mass air flow sensor to fail.
Check Engine icon on instrument panel
The first signal that the car is starting to have problems with the sensor is.
In this case, if you connect to the electronic engine control unit, you can identify the following malfunction: “ Insufficient signal level of the mass air flow sensor ". This is what means that the sensor has failed.
Main features
So, let's look at the main signs of a malfunction of the DMVR:
- Malfunctions of the main power unit , namely: the car stalls at idle.
- , also one of the fundamental factors in the interruption of the operation of this node.
- When changing gears, the car it just stalls.
- . This is due to the fact that the fuel mixture ratio is incorrect.
Now that the signs of a malfunction are clear, we can consider the factors that cause the failure of the DMVR:
- Destruction or breakage of wiring inside the product.
- Loose fixation of the wire block.
- Damage to the inside of the element.
- Oxidation of contacts.
- Wear or burnout due to short circuit.
Often the air flow sensor fails after washing the engine.
Checking the mass air flow sensor using a multimeter
In order to check the mass air flow sensor, it is not necessary to go to a car service center and spend a lot of time and money. To do this, you need a regular tester or multimeter., which can be bought for 300 rubles on the market.
Location of the DMVR sensor
To check the DMVR, you need to know the pinout of the contact group.
So, let's look at the pinout of the mass air flow sensor:
DMVR pinout
- Contact №5 (in Bosch sensors, as a rule, there is a yellow wire coming from it) - is responsible for supplying an incoming signal from the ECU;
- Contact №4 (gray or white) - is responsible for powering the device;
- Contact №3 (green wire) - responsible for grounding;
- Contact №2 (pink-black) - wire through which information from the sensor is transmitted to the main relay of the fourteenth.
To determine serviceability, you do not need to remove the sensor. The multimeter is set to measure direct current up to 20 volts. Next, follow the step-by-step instructions:
The principle of checking the DMVR sensor
| Tester readings (voltage, V) | Air flow sensor condition |
|---|---|
| 0.006 - 1.01 | Only new sensors produce this voltage; after several weeks of operation it increases by several hundredths; |
| 1.01 - 1.02 | Normal operating voltage of a device in constant operation; |
| 1.03 - 1.04 | The device has used up approximately half of its working resource; |
| 1.04 - 1.05 | The MAF voltage is in an extremely worn condition, replacement is recommended; |
| Above 1.05 | Such a sensor does not work, or it works, but sends distorted signals to the ECU. |
Depending on the readings and interpretation, we carry out the appropriate repair operations.
conclusions
Checking the VAZ-2114 mass air flow sensor using a multimeter is quite easy and can be done even by a novice motorist. So, if a car enthusiast is not able to do this with his own hands, he will have to contact a car service.
Almost every owner of a VAZ 2110 (as well as owners of later VAZ 2112, VAZ 2114, VAZ 2115, etc.) encountered problems associated with abnormal operation of the mass air flow sensor (MAF). Even a slight increase in the error of the readings given by this sensor can seriously disrupt the activity of the central controller, which, in fact, based on this information about air flow, controls the injectors and the ignition system. As a result, the engine loses part of its power, average fuel consumption increases, dynamic performance worsens, and the amount of CO in the exhaust gases increases. Meanwhile, frequent failures of the mass air flow sensor are explained not only by the low reliability of this element (although let’s be honest, the overall quality of the domestic air mass flow sensor also wants to be better), but also by the design features of products from the Russian automotive industry. The fact is that with the currently adopted dual-circuit engine crankcase cooling system, under certain conditions, part of the exhaust gases passes through the idle line, simultaneously affecting the sensitive element of the mass air flow sensor, and the oscillatory reverse flow of gases in the intake tract also causes some harm. If we remember the quality of our gasoline, it becomes clear that it will take very little time for tar deposits to appear on the sensor elements, which can change the characteristics of the sensor and even completely disable it.
If you act within the rules, then if you suspect a failure of the mass air flow sensor, it is best to check it using a special diagnostic device, such as the DST-6, but if you wish, you can take a simpler path and make do with a publicly available digital multimeter (tester ) with a measurement limit of 2V. In order to perform the test, we need to get to the signal wires of the sensor without disconnecting it, and this can be done by inserting thin probes or ordinary needles under the rubber seals directly to the terminals. When checking, the voltage is measured between the yellow output signal wire (usually located closer to the windshield) and the green ground wire. Having achieved reliable contact, turn on the ignition without starting the engine. For a normal sensor, the measured voltage should be in the range from 0.996V to 1.03V. If the voltage is higher, then you should look for a way out of the situation, namely, change the sensor or try to restore it. A new mass air flow sensor does not cost much, and if you consider that out of 10 sensors subjected to “reanimation”, about eight sensors restore their characteristics, then an attempt to extend the life of the mass air flow sensor seems quite justified.
By and large, all restoration operations involve simple disassembly and washing of the most significant elements of the sensor and, in particular, its sensitive membrane.
Before you begin such work, you must firmly understand that the sensitive element of the mass air flow sensor does not tolerate physical impact, which means that it is recommended to forget about any tampons, matches, brushes, etc. You should also be very careful when choosing a washing liquid, since many solvents can cause irreparable damage to the thin contacts on the membrane, which are secured with a special resin. Be that as it may, you can safely use carburetor cleaner or regular alcohol as a cleaning agent.
When preparing for cleaning, you will need to remove the pipe from the mass air flow sensor, for which you will need a set of sprocket keys to unscrew the tricky self-tapping screws (later they can be replaced with regular ones, crosswise). After removing the pipe, the condition of the sensor is assessed and, as a rule, surfaces covered with oil deposits are visible at first glance. Washing is carried out by supplying a jet of detergent into the upper channel of the measuring element. To be safe, this procedure can be repeated, waiting until the previously applied liquid has completely dried.
After washing the sensitive element of the sensor, do not forget to thoroughly clean the filter of the pipe.
Having completed the restoration procedures, the sensor is assembled, installed in place and the values it produces are checked again.
Optimal operation of the power unit in the “Ten” depends on many parameters and characteristics, in particular, on the quality of the air-fuel mixture. To monitor the correct ratio when forming a combustible mixture, the VAZ 2110 uses a mass air flow sensor. You can learn more about what this device is, how to diagnose and replace it, from this material.
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Principle of operation
What is a mass air flow sensor and what is its operating principle? Let’s say right away that you cannot confuse the mass air flow sensor with the outside air temperature controller, since these are two completely different devices. The primary purpose of the flow meter is to calculate the required volume of air flow that enters the engine cylinders. This air is one of the components in the formation of the air-fuel mixture. The mass air flow sensor itself in the “Ten” is located behind the air filter element.
In order for the engine to operate in normal mode, when forming a combustible mixture, the ratio of substances must be strictly observed - 1:14. If these proportions are not observed, the engine will not operate correctly, which will ultimately lead to excessive consumption of gasoline or a decrease in the dynamics and power of the vehicle. Thanks to the flow meter, the air flow is transferred to the engine cylinders in certain portions. Data on calculating the volume of air flow entering the engine is sent to. In accordance with the data received, the ECU calculates the required amount of fuel.
When the driver presses the gas pedal, the volume of supplied air flow increases significantly, and accordingly, this leads to an increase in gasoline consumption. If the vehicle moves evenly, then the portions of fuel and air flow that enter the cylinders will also be the same at each cycle. When you press the gas pedal, the throttle opens, which ultimately leads to an increase in the supplied air, and this also contributes to an increase in the load on the power unit.
Possible malfunctions and ways to eliminate them
Now let’s look at the main symptoms of a malfunction that will help determine if the flow meter is broken:
- Increased gasoline consumption. In this case, the problem can be identified by the readings of the on-board computer, if the latter calculates the amount of fuel. If the mass air flow sensor breaks down, gasoline consumption may increase by one liter or more.
- Reduced engine power during operation.
- The car engine began to work less stably. The car takes longer to accelerate, and sometimes the engine picks up speed uncharacteristically quickly.
- The Tens power unit does not start or starts, but not immediately, after several attempts.
- Floating idle speed.
Of course, such symptoms of problems can also be associated with other malfunctions, for example, spark plugs, distributors and other components of the ignition system. Therefore, in order to accurately verify that the flow meter is not working, you will have to check the device. As for troubleshooting methods, the mass air flow sensor itself is usually not repairable, so in most cases, if there is a problem with its operation, the device is simply replaced. It happens that the reasons are due to poor contact of the device with the vehicle’s on-board network, so before replacing, we recommend checking the connection circuit, as well as the quality of contact of the device with the connector.
Methods for checking sensor functionality
How to check the flow meter yourself? There are several diagnostic options, we suggest you familiarize yourself with each of them (the author of the video is the Bezdelnik TV channel).
Shutdown
First you need to try disconnecting the flow meter from the power supply. To do this, you need to start the engine and let it run for a while. Next, you will need to disconnect the plug from the flow meter - after this, the emergency mode of operation of the motor should be activated. In this case, the calculation of the volume of the required air flow will be carried out in accordance with. If, after switching off, you notice that the engine began to work more correctly and at the same time it became more dynamic, then the mass air flow sensor definitely needs to be replaced.
Diagnostics using a multimeter
Diagnostics can be performed using a multimeter; for this we recommend that you read the operating instructions for the tester. The device must be configured in the DC voltage measurement mode; it is usually marked with the symbols DCV or V.
To ensure that connecting the device does not cause difficulties, you need to know exactly the pinout of the device:
- black-red or pink contact is a connection to the control module;
- green is ground (grounding, ground), connected to the body or battery;
- gray-white contact - output voltage;
- yellow - used to supply current to the input.
Diagnostics with a multimeter is performed as follows:
- To begin with, the tester should be turned on and the voltage value set on it to 20 volts, and then the probes from the device are connected to the corresponding contacts on the plug.
- To make the connection more convenient, you can use pins; you will need two of them. Each of them is installed in a hole with green and yellow contacts. Then you will need to connect the probes of the device to these pins.
- The next step is to activate the ignition and measure the voltage. Read more about the test results below (the author of the video is the IZO channel)))LENTA).
On a working device, the voltage level will be around 1.01-1.04. If the readings are between 1.02 and 1.05 volts, this indicates that the device will need to be changed in the near future. If the readings obtained are higher, then the flow meter must be replaced because it is faulty.
It should be noted that during operation, the voltage parameter will only increase, since the resistor components of the device wear out, and the resistance value, accordingly, decreases. You can also accurately determine the voltage using the on-board computer, if it has the appropriate function. To search, go to the flowmeter voltage section and find the U value.
Visual inspection
As for visual diagnostics, first of all it is necessary to check the condition of the corrugation in which the flow meter is installed, as well as the device itself. If, as a result of the check, you see traces of motor fluid or condensation, then it is possible that the device does not work for this reason. In some cases, cleaning the device from contaminants allows the flowmeter to resume operation and prevent possible replacement. It should be taken into account that contaminants usually accumulate as a result of infrequent replacement of the air filter element (the author of the video about the regulator malfunction is the channel In Sandro’s Garage).
If you notice traces of engine fluid, then there is a possibility that the reason lies in a clogged oil seal, or the problem may lie in exceeding the permissible level of lubricant in the crankcase. When cleaning is complete, you will need to make a visual inspection of the regulator - on the front of it you can see the rubber seal that is used for sealing. The seal is necessary to prevent uncleaned air flow and it may be that the rubber band moves a little - this will lead to the accumulation of dust on the flowmeter grid.
DIY replacement and installation instructions
How to replace the regulator in a garage:
- First, turn off the engine and ignition.
- Next, open the hood and find the location where the mass air flow sensor is installed. You need to disconnect the plug and wiring from the regulator.
- After this, unscrew the bolts that secure the clamps, and then disconnect the intake manifold pipe. This line is connected to the air filter housing.
- After completing these steps, you must remove the flow meter from its installation location. Before installing a new mass air flow sensor, it is necessary to clean or rinse the installation site. Further installation and assembly is carried out in reverse order.
Photo gallery “Changing the flow meter”
Features of cleaning the regulator
How to clean the regulator by washing? In some cases, cleaning actually helps to extend the life of the flow meter; this process can be called a component of repair. For cleaning, you can use specialized products designed for this specific purpose. You can also use WD-40 liquid or carburetor cleaner.
How to wash the flow meter yourself:
- First, you need to dismantle the mass air flow sensor, we talked about this in more detail above.
- Once you have the device in your hands, you will need to use a cleaning agent to wash all sensitive components of the regulator. In particular, we are talking about wire mesh, thermal sensor, and contacts. When cleaning, be as careful as possible and regularly monitor the level of pressure of the jet from the cylinder. Please note that the stream itself should not be too strong; it is best to keep the balloon at a distance of approximately 5-10 cm from the device.
- Wait a few minutes, then apply the cleanser again, wait a little again. The cleaning procedure must be carried out several times, but as practice shows, usually three times is enough to obtain the desired result.
- Then, you need to pour distillate with alcohol into a medical syringe (you can find it in any pharmacy). Using a syringe, treat all sensitive components of the device, as well as contacts, this will allow them to be thoroughly cleaned. Loading...
Video “Features of replacing a flow meter in a garage”
How the replacement procedure is carried out and what points should be taken into account when performing this task - find out from the video below (author - channel In Sandro's Garage).
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 this error can be compensated for by adjusting the injection ratio. 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 the response speed and the time of the 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 a working sensor, these parameters should be 2-20ms during the transient process and *1.03V after it. Moreover, the shorter the transition process time, 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.
A completely faulty mass air flow sensor can be easily diagnosed: by measuring the voltage, taking readings with a diagnostic tool, etc. The trouble is that a completely faulty mass air flow sensor is very rare. SOMETIMES it causes the "CE" diagnostic, basically the car does not drive and does not start well.
In reality, a faulty mass air flow sensor is most often not diagnosed using available methods.