The main signs of a malfunction of the mass air flow sensor are loss of engine power, difficult starting, “floating” engine speed. To find out the exact cause of the flow meter failure, you need to visually inspect the device and then test it with a scanner (via Openidag), a voltmeter or a motor tester.
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.
What is a mass air flow sensor, why is it important and how to diagnose its malfunction
Over the past three decades, engines with distributed and direct fuel injection have finally supplanted all other types of designs. It would seem that this is a considerable period of time, but engineers have not been able to overcome the “childhood diseases” of important electronic components, including the mass air flow sensor (MAF), which is responsible for the composition of the air-fuel mixture. Let's remember how the mass air flow sensor works, why it is so important and how to diagnose its malfunction.
What is DMRV
Modern engines use two types of power supply systems: with distributed injection, the nozzle supplies fuel to the intake pipe, with direct injection, it supplies fuel to the combustion chamber. For both systems, the correct operation of the mass air flow sensor, which was once mechanical (vane type), but is now devoid of moving mechanical parts and made hot-wire (from “anemo” - wind), is important.
Factory air flow sensor made in Germany for a VAZ engine
The mass air flow sensor can be installed not only on a gasoline engine, but also on a diesel engine, where the operation of the EGR valve (exhaust gas recirculation system) is “tied” to it.
As old-school drivers used to say, an internal combustion engine does not work in two cases: there is nothing to burn or there is nothing to set it on fire. The mass air flow sensor precisely informs the electronic control unit about the amount of incoming air, the oxygen of which becomes the “fuel” for the working mixture. Having received such a signal, the ECU can ensure the most complete combustion possible. The device, located in the intake tract, consists of two resistors, which can be designed in various designs. In the first case, the resistor is exposed to passing air: when the flow intensity changes, it cools and its internal resistance changes. In the second case, it is not blown - based on the difference in readings from two resistors, the volume of air that needs to be supplied to the cylinders is calculated.
The sensor is supplied to the aftermarket with protective caps to prevent contamination during transportation.
This is what the sensor looks like on a regular VAZ engine. It will not be possible to remove it from the case without a special key.
The removed sensor is in its “bare” state. The sensitive element is clearly visible
Based on the data on the mass and temperature of the incoming air, the ECU determines its density, and also calculates the duration of opening of the injectors and the amount of fuel supplied to the combustion chamber. In general, the mass air flow sensor is important for achieving maximum engine power, for more complete combustion (environmentally friendly), and for economical driving. The failure of this sensor, like most others, causes the Check Engine warning light to go off.
The check engine light can come on for any reason. If there is no on-board computer with a diagnostic function, you will have to go to a service station where there is a scanner
However, the owner does not always associate the triggered “check” with the mass air flow sensor - especially if the engine runs without any interruptions, and the dynamic characteristics of the car have not deteriorated at all. Therefore, it is important not to leave the illuminated engine malfunction indicator unattended, but to consider errors with the diagnostic computer.
MAF or DBP?
The absolute pressure sensor (MAP), together with the temperature sensor (DTS), also controls how much air enters the intake manifold. Based on these readings, the controller generates a pulse command to the injectors. An important difference between DBP and MAF is the absence of air in the housing, since this sensor works based on measuring the difference in inlet pressure and pressure in the vacuum chamber. A design feature of the DBP is a highly sensitive diaphragm, which expands under the influence of pressure in the intake manifold. This process affects the resistance of the strain gauges, as a result of which the voltage changes.
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.
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The main signs of a malfunction of the mass air flow sensor are loss of engine power, difficult starting, “floating” engine speed. To find out the exact cause of the flow meter failure, you need to visually inspect the device and then test it with a scanner (via Openidag), a voltmeter or a motor tester.
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.
What happens if you turn off the mass air flow sensor?
Let's start with the fact that when the flow meter is turned off, the engine goes into emergency operation mode. What could this lead to? Depending on the car model and, accordingly, the firmware, the engine will stop (as on Toyota), increase fuel consumption, or... nothing. Judging by numerous messages from auto forums, experimenters note increased agility after shutdown and the absence of failures in engine operation. No one has carried out careful measurements of changes in fuel consumption and engine life. Whether it is worth trying such manipulations on your car is up to the owner to decide.
Replacing the air flow sensor
To replace the sensor with your own hands, you need to prepare a shaped screwdriver and a “10” key.
The replacement procedure consists of the following steps:
- First you need to turn off the ignition and open the hood.
- Then you need to disconnect the negative terminal on the battery.
- At the next stage, you need to loosen the clamp with which the corrugation is attached to the mass air flow sensor.
- Next, remove the corrugation from the pipe.
- Then you need to bend the comb and disconnect the sensor connector.
Disconnecting the sensor connector
Thus, if the car stalls and has all the signs of a breakdown of the mass air flow sensor, then before you start repairing it, you should check the level of its signal, it should not be low, perform a full diagnosis of the car and repair all faulty components and parts.
It is important to undergo regular vehicle inspections and perform timely maintenance, then the parts and components will last longer.
Why might the mass air flow sensor fail?
Mass air flow sensor malfunctions may be related to air quality. When entering the air tract, the air must be clean, which is ensured by regularly installing a new filter. Replacement is more often required when using the car in dusty regions. It is also worth paying attention to the risk of oil penetration through the breather, which indicates the importance of preventive maintenance of the ventilation system. Also, water penetration into the air path is unacceptable. When washing the engine, you should cover the path with film or remove it completely. By observing the operating requirements, you can extend the service life of the mass air flow sensor.
Video “Checking the mass air flow sensor using a multimeter”
This video from the “Simple Opinion” channel demonstrates how to check the mass air flow sensor with a multimeter.
Help me figure out if the DMRV malfunctions, immediately change the DMRV or clean it. And how to check the DMRV. and how did your car behave with a faulty air sensor and after replacing it?
Comments 11
But when I turn off the mass air flow sensor, the car stalls, is that how it should be?
Soak it in gasoline overnight. It helped me when carb cleaner didn’t help!
I turned off the DMRV today, nothing has changed
That means it’s not a matter of the mass air flow sensor!
It’s just that the diagnostics already show that the DMRV has been screwed up and the control unit is blocked; it’s already in emergency mode. I don’t have a check on my car. I have an EPS (control of engine electronics). I think I’ll probably buy a new one.
YOU CAN check! turn it off and that's it! The car will start working in an “emergency” state, the “check” will light up! and try to ride! Good luck!
The spark plugs are blown, when you give it gas, there is black smoke at rpm. As they say, the consumption increases
first, of course, try to clean it, it’s cheaper than changing it right away, if that doesn’t help, then of course replace it. Symptoms of a dead sensor can be either separately, but more often all together - it becomes dull when accelerating, eats gasoline in buckets (for 1.6 liters 12-13 probably), the smell of gasoline from the exhaust pipe when the engine is running, black carbon deposits on the spark plugs. In general, if the computer says that there is a weak signal from the DMRV, then it is half-dead, but it can be brought back to life) regarding cleaning - I would not recommend cleaning it with carbkiner, it is a very active mixture. although people cleaned it, it seemed without consequences, at least at first)) (certain types of air flow sensors, tape ones definitely cannot be cleaned) I cleaned mine like this - I warmed up a glass of alcohol in the microwave, lowered the sensor there to let it dry (this three or four times), then I very carefully cleaned those very sensitive elements with a pen and alcohol. I took photos before and after the event - the difference is noticeable, and this difference was visible only during macro photography and when viewing the photo on a 16x zoom)) after cleaning, the smallest wire on the sensitive elements became visible.
Should the car stall when the air flow sensor is turned off?
With it turned on, is the DMRV to blame for this? And if the DMRV is working, should it be even better than with it disabled?
Comments 11
Without a mass air flow sensor, the consumption is like a tank with a trailer. It drives quickly, but is expensive :-) Even though it works with the mass air flow sensor and other sensors, it drives just as fun. Check all the sensors, take them to an electrician or connect the wire to the computer yourself. Nowadays you can’t find a good MAF, when my own one burned out, then I changed it every month, in different stores and different companies... it’s all bullshit
Is black smoke coming out of the muffler, with soot?
When the mass air flow sensor is turned off, the mixture becomes rich. Therefore, it becomes a little more fun, but the consumption is cosmic.
Perhaps the mass air flow sensor is not preparing the mixture correctly due to malfunctions of other sensors. Temperature for example
Diagnostics made no errors
No, I didn’t do it myself, well, there were mistakes, but they didn’t affect the engine
Look at what your brains show on DTV and DTOZH, compare with reality, and then draw conclusions. Errors in temperature sensors are difficult to track with conventional diagnostics. And when you have weather there on Mars, then the mass air flow sensor, no matter how working it is, will not save the situation
Diagnostics made no errors
errors on sensors usually pop up only in extreme cases, roughly speaking, when the sensor doesn’t seem to work at all, I’ve also encountered this myself, and if it seems to show no violations or failures, the brains think that everything is fine with it, and they don’t care what it’s doing this may underestimate or overestimate. On normal cars, to analyze the situation, the brains have long been connected to an outside temperature sensor, for which the brains also make corrections and if there is a sharp discrepancy, they give an error, but in our case, at most it can be attached to the tidy
The main signs of a malfunction of the mass air flow sensor are loss of engine power, difficult starting, “floating” engine speed. To find out the exact cause of the flow meter failure, you need to visually inspect the device and then test it with a scanner (via Openidag), a voltmeter or a motor tester.
How to check the mass air flow sensor: diagnostics of the air flow system
On domestic cars, a very common reason for a trip to the service station is the mass air flow sensor. This device is often located near the air filter and is responsible for the amount of air that enters the power unit. By measuring the amount of air, the sensor determines whether the engine has any problems, and also monitors the quality of the combustion chamber and the process of enriching the fuel mixture. Not only engine power, but also safety in its operation depends on these important aspects. It often happens that the mass air flow sensor becomes the most important problem in a car, which spoils the quality of the trip.
Many drivers of cars of the VAZ 2110 family have encountered problems with this unit. Today, most owners of these cars know how to check the mass air flow sensor and adjust its normal operation or replace it with a new one. If you have a more modern car, it is not recommended to check and change the sensor yourself. It is better to carry out the work at a specialized station and receive a guarantee for the high quality of your proposals.
What are the first symptoms of a MAF failure?
The mass air flow sensor not only measures, but also controls the flow of air into the engine. The operation of all technical parts of the machine is controlled by computer systems, which in most cases are controlled automatically. This is why the work of the mass air flow sensor is so important. It affects the quality of operation of the power unit and its suitable operating modes. Such important roles in a vehicle make the sensor a real problem when it breaks down.
The main features of sensor failure can be described by a list of several symptoms of problems. But it is also worth considering that in some cases it is impossible to determine the origin of the symptoms of a problem on your own. Sometimes it’s easier to pay for high-quality diagnostics than to look for the causes of a particular problem yourself. Among the typical features of a mass air flow sensor failure, the following behavior patterns can be identified:
- the treasured Check Engine light comes on on the dashboard and requires you to perform engine diagnostics;
- gasoline consumption increases, and the increase may be quite high and unpleasant;
- when stopping near a store for a few minutes, starting the car becomes a real problem;
- the dynamics of the car decrease, acceleration becomes slower, and the “pedal to the floor” tactic does not work at all;
- the power is not felt especially on a hot engine; on a cold engine the behavior practically does not change;
- all problems and malfunctions arise in the vehicle only after the engine has warmed up.
Principle of operation
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The sensor consists of platinum filaments (which is why it is not cheap), through which an electric current is passed, heating them. One thread is the control thread, air passes through the second, cooling it. The sensor produces a pulse-frequency signal, the frequency of which is directly proportional to the amount of air passing through the sensor. The controller records changes in the current passing through the second, cooled filament and calculates the amount of air entering the engine. Depending on the frequency of the signals, the controller sets the duration of operation of the fuel injectors, adjusting the ratio of air and fuel in the fuel mixture. The readings of the mass air flow sensor are the main parameter by which the controller sets fuel consumption and ignition timing. The operation of the flow meter affects not only the overall fuel consumption, mixture quality, engine dynamics, but also, indirectly, the engine life.
