Detonation sensor: signs of malfunction (VAZ, Kalina, Priora, Toyota, Gazelle)

This article will consider what a knock sensor is. Symptoms of the failure of this device will also become known to you. A modern car is a whole complex of electronic components that are responsible for the operation of the engine as a whole. Of course, there are a lot of service stations on the territory of our country. But the failure can happen at any time and at any distance from the nearest service. The knock sensor is a very small device, but it affects the correct operation of the engine.

What is a knock sensor?

It is necessary for information on the operating mode of the internal combustion engine. The control system of ICE is rather complicated, it includes a lot of devices, one of which is a sensor that signals the appearance of detonation in the engine. In addition, it allows not only to determine the presence of detonation knocking, but also to measure their magnitude. This phenomenon occurs when the fuel is not fed into the combustion chamber. In particular, if the ratio of air and gasoline is violated. Due to the timely detection of these knocks by the control system, the fuel-air mixture is adjusted for composition. The sensor has a very convenient location - between the second and third cylinder. In other words, clearly in the middle of the engine block. This allows you to fix even the smallest detonation knock on the motor. Such things happen if the knock sensor fails. Symptoms of a malfunction, "Priora" this or any other car, are the same.

How does the knock sensor work?

Modern cars use designs of broadband and resonant type. They have either one or two outputs for connection to the electronic control unit. The basis is a piezoelectric element - a small plate that produces electricity under the impact and vibration. And there is one regularity: the stronger the impact, the more energy will be generated by the plate. Similarly, with vibration: the higher its frequency, the higher the output voltage of the piezoelectric cell.

These parameters can be monitored by the knock sensor. Symptoms of a malfunction ("Gazelle" in this respect is no different from the rest of cars) are similar. All data on the value of the voltage on the plate are fed to the electronic control unit, built on the basis of the microcontroller. It allows to correct the ignition timing, and also changes the reaction of ignition of the fuel-air mixture in the combustion chamber.

What is detonation?

But before talking about the sensor of detonation, the signs of VAZ-2114 malfunction and other models, you need to find out why this phenomenon occurs. Surely you heard a metal knock on the carburetor engines when the gas pedal was abruptly squeezed. Usually this is dumped on the fingers, but this opinion is not entirely correct.

The whole problem is that the beginning of the combustion of the fuel-air mixture and the leap of a spark between the electrodes of the candles is not timely. Hence the increase in temperature and pressure directly in the combustion chamber. As a result, explosions and self-ignition of the fuel mixture begin to occur. A blow of the blast wave on the engine wall is very similar to a metallic knock.

The main causes of knock detonation

Having dealt with what this phenomenon is, it is worthwhile to talk about the causes that cause detonation. Of great importance is gasoline, its quality and brand (octane number). The lower the last parameter, the less stability gasoline has to detonation. On the quality of talking is not necessary, refuel at proven gas stations, so as not to have problems. Note that the knock appears quite often after refueling at suspicious stations. True, the detonation sensor VAZ, the signs of a malfunction which are considered in the article, allows you to get rid of the knocking in a timely manner.

In addition, one of the reasons for the occurrence of knocking is the incorrectly set advance angle. It is possible that the timing belt has moved a few teeth, hence the disruption of the work. Often the reason for the appearance of detonation is a poor fuel-air mixture. As a result, the fuel evaporates less and absorbs much more heat. Hence, a sharp temperature jump and the appearance of knocking. Such a breakdown can be detected by looking at the spark plug electrodes.

What else can cause a detonation?

The main reason for the appearance of detonation is a sharp increase in the temperature in the combustion chamber. Also, detonation knocking can provoke a fault in the valves. For example, the work of intake and exhaustion has been disrupted. At the same time, exhaust gases can not escape unhindered. This causes the appearance of detonation in the engine. Of no less importance are those conditions in which the operation of the internal combustion engine takes place. In particular, the qualitative composition of the mixture supplied to the combustion chamber. And then the detonation sensor of the VAZ will help, the signs of a malfunction of which we now find out. It allows you to adjust the engine.

It is possible that there is an increase in the maximum permissible load on the ICE, as well as the appearance of a large amount of carbon in the combustion chamber and on the electrode of the candles. If operation occurs at high ambient temperatures, then the appearance of detonation knocking is simply inevitable. Of course, there is overheating of the internal combustion engine, all its elements. Strongly wear out the crank mechanism, which entails premature failure of the ICE.

What if the sensor breaks down?

It is possible that the knock sensor can work with errors. At the same time the engine starts to touch. In this case, you will need to diagnose the device. First of all, you should pay attention to the condition of the wiring, through which the sensor is connected to the car's control system. Pay special attention to the condition of the connectors. If they are plaque or they have oxidized, it is necessary to perform a sweep. Thus, any knock sensor is checked. "Kalina", the signs of malfunction which are no different from those given in the article, needs timely care and replacement of elements.

But in the case when no external damage is detected, we can conclude that there is a breakdown of the sensor itself. All work can be done independently. To remove the knock sensor, you will need a small set of tools. Typically, the removal is done with a key on 20 or 13. It all depends on what type of device is used on your car.

Easy way to diagnose

After removal, connect the voltmeter with a minus terminal to the sensor housing, plus a positive lead to the wire coming from it. The measurement limit of the voltmeter should be set to 0.2 V. Now, take into account the principle of the detonation sensor. It was said above that the plate begins to generate electricity during the impact. Therefore, you need to hit several times on the body of the device. At the same time, their strength must be different. Depending on how much you hit the knock sensor, the voltmeter will change.

If they do not change, the device breaks down. In this case, only a complete replacement will help. You can buy the sensor in any car dealer. Please note that there are several designs of this device. Therefore, take the old sensor with you as a sample. The service life of the knock sensors is very high. They are practically eternal, because in them there is simply nothing to break. It is also worth noting that different cars use the original detonation sensor. Symptoms of a malfunction (Toyota or VAZ, it does not matter) will be the same, but the level and shape of the output signal may differ significantly.

Main faults in the sensor circuit

As you have noticed, there is no difficulty in replacing the knock sensor. But it happens that even after installing a new device, the engine does not work correctly. In such cases it is necessary to completely diagnose the wiring of the car. The lamp lights up, which indicates the presence of a breakdown in the engine, knocking occurs, and unstable operation takes place.

A common cause of failure lies in the signal wire, which can break off. In addition, the integrity of the shielding braid may be impaired. Often there is a short circuit of the sensor leads to each other. Regardless of whether the fault lies in the sensor itself or in the wiring with which it connects to the electronic control unit, the external characteristics will be the same.

conclusions

Now you know what a knock sensor is. The symptoms of VAZ-2110 and other cars are not a secret to you either. And you can easily carry out the diagnosis and replacement of such a simple device. The main thing is to pay attention in time to the occurrence of knocking in the engine. And try not to refuel at unreliable gas stations.