Why does the engine knock after turning off the ignition?

On gasoline engines, car owners most often observe detonation when the ignition is turned off. The engine also detonates when the ignition is turned on. But on diesel engines, detonation occurs less frequently. This happens in several ways, which will be discussed below.

But first, let's figure out what detonation is and why it happens.

The main causes of detonation when the ignition is turned off:

• unsuitable fuel: if the fuel is not of the type required for the normal operation of the internal combustion engine, active combustion occurs, close to the speed of explosion. This happens when the car is filled with AI-92 instead of the required AI-95. This phenomenon causes the release of excess thermal energy, which negatively affects engine operation;

Monitor the quality of gasoline. Refuel only at proven gas stations.

• Another reason why the engine knocks after the ignition is turned off is excessively early ignition. The need for this installation arises to increase the engine’s susceptibility to opening the throttle, which in turn can lead to excessive heating. Another reason for early ignition is unsuitable spark plugs for this type of engine. Candles keep the combustible mixture under control, preventing it from igniting more strongly. With a high degree of combustion, the volume of the combustion chamber changes, then the temperature rises;
• overheating is another possible reason to understand why the engine is knocking. To do this, you need to check the amount of coolant and the thermostat.

Prolonged use of the vehicle at low speeds can cause carbon deposits. ICEs require heavy loads from time to time while complying with traffic rules.

Remember that timely maintenance and inspection of the car immediately in the event of emergency situations will save your car and allow you to avoid additional expenses and accidents on the road.

The good condition of the motor is characterized by smooth operation without unnecessary sharp noises. Any deviation from the “norm” is not welcome - various knocks and extraneous clangs indicate a critical operating mode of the parts. It is not recommended to ignore such symptoms - the power plant may fail at the most inopportune moment. Irresponsibility is assessed not by small expenses for diagnostics, but by large expenses for major repairs.

Noise 5: wind noise/whistle - the higher the speed, the more it blows in the car with the windows closed

The wind swirling around various parts of the car's body, such as the front grille, headlights, and bumpers, creates natural noise as the speed increases. Typically, such noises are not heard inside the car due to sound insulation. By the way, usually when designing a car and testing it in a wind tunnel, engineers design the body in such a way that even at high speed no wild noise is generated.

If your car makes excessive wind noise at speed, it may be due to the installation of additional accessories such as a trunk, spotlights, wing, spoiler or side deflectors on the windows. It is also quite possible that strong noise at speed is associated with loss of body geometry after poor-quality restoration after an accident.

Solving this problem again involves trial and error. For example, if you suspect the noise is coming from the roof rack, remove it and test the car at speed without it.

Five Other Causes of Car Noise...

1. A loud sound from under the car, similar to air popping. It is possible that your exhaust pipe is damaged or the manifold gasket is broken. 2.Moaning sound when turning the steering wheel. Most likely the steering pump bearing is failing.

3.High-pitched squeal when pressing the brake pedal. Most likely, your car's brake pads are worn out.

4. Rumbling, grinding sound from the wheels that comes and goes. Make sure the wheel nuts are not loose, especially on the left side.

5. Wind noise from doors and windows. Check for dust and dirt. Because of this, doors and windows often do not fit tightly in the right place and can easily cause whistling/wind noise in the cabin.

What is detonation and how to determine it

Definition and essence

Detonation is the process of combustion of a fuel-air mixture at a critically high speed, leading to a sharp increase in pressure and temperature. The phenomenon occurs at the stage of a sharp increase in pressure in the cylinder and combustion of the mixture in the near-wall layers during the compression stroke.

Instant combustion of prepared products causes shock waves to propagate in the combustion chamber at speeds of up to 1,200 m/s. During conditioned combustion, shock waves also arise, but the intensity of their propagation does not exceed 50 m/s.

When a shock wave collides with obstacles in the form of cylinder walls and pistons, a characteristic detonation knock is produced. The opinion that it is the piston pins knocking has no basis.

Consequences

How dangerous detonation is can be logically assumed based on the definition of the phenomenon. It is quite clear that the action of shock waves does not have the best effect on the performance of the motor:

• Increasing the transfer of thermal energy to the piston bottom and the walls of the combustion chamber and their associated overheating.
• Destruction of intercylinder partitions and pistons.
• Elimination of the oil layer on the cylinder walls.

Symptoms of a problem

Before you can figure out why detonation occurs, you need to identify it. An undesirable phenomenon occurs only when the engine is running. Hence the consequence - when switching off or after turning off the ignition, the engine cannot detonate. Yes, and at idle speed it is quite difficult to meet it, except when starting on gas.

But under load you can hear metallic knocks. Especially when accelerating uphill in high gear and low revs. The shock wave also counteracts the upward stroke of the piston, resulting in a loss of power and increased fuel consumption.

Greenish or black smoke from the exhaust indicates that things are going wrong. The unpleasant phenomenon took place and has already ended. Untimely recording of the fact led to the fact that broken parts of aluminum parts fly out through the outlet.

Main reasons and how to eliminate them

It is worth analyzing recent changes that resulted in the occurrence of strong or light knocks:

• I visited a gas station and was filled with low-quality or low-octane gasoline. Be guided by the gas station rating when choosing a gas station network. In extreme cases, an octane booster will help.
• The ignition system of the carburetor engine was adjusted. Detonation loves earlier ignition, so it is necessary to maintain a balance in adjusting the advance angle.
• The “injector” was re-flashed in order to increase efficiency. A lean mixture creates favorable conditions for unstable operation.

Constructive ways to eliminate engine detonation

To properly eliminate engine detonation, it is necessary to clearly outline the causes of the problem. If immediately after adding new fuel the engine begins to vibrate and make noise, you can definitely say that the cause of detonation lies in the wrong octane number.

It’s better not to experiment and not add suitable gasoline to what you have. It would be more correct to drain the old one and fill it with the type of fuel that is suitable for the car engine.

If detonation is caused by carbon deposits in the combustion chambers, you can let the car drive for a few minutes at high speeds. As a preventative measure, experts recommend giving the engine maximum load once a week.

If a diesel engine detonates, a motorist may notice dirty green or black exhaust. In this case, it is already pointless to carry out a “rescue”, since the pistons are completely destroyed.

If the reason is hidden in the incorrect operation of the spark plugs, it is necessary to completely change the set. In general, detonation due to spark plugs occurs quite rarely, but nevertheless, their timely diagnosis should not be neglected.

In addition, it is necessary to monitor the engine cooling system and adjust the ignition timing in time.

Can a car engine detonate when turned off: let’s understand the aspects

It is wrong to classify uneven engine operation or any other knocking as a sign of detonation. To avoid mistakes, the best option would be to find out what the detonation mode sounds like in practice. For example, watch thematic video files.

Dieseling

As already noted, an undesirable phenomenon can appear exclusively on a functioning motor. How then to qualify the operation of the power plant with the ignition off? The mechanics' answer is short - dieseling. Its nature is different: self-ignition of gasoline, identical to the working process of a diesel engine.

Beginners who have caught up on their knowledge base on gasoline internal combustion engines will immediately object, citing a couple of arguments “against”: high-octane fuel has poor self-ignition ability, and the compression ratio in a gasoline engine is lower. All this is true, but when the unit is stopped, favorable conditions are created for dieseling.

1. Fuel supply to the cylinders.
2. Low crankshaft speed.

In reality the process looks like this. The power plant is turned off, the crankshaft rotation speed drops, fuel is supplied. The time allotted for ignition of the mixture increases.

Under such conditions, a spark from a spark plug is not needed to ignite the fuel - a gradual increase in pressure and temperature is sufficient. After completing the power stroke, the crankshaft speed increases, and self-ignition does not occur. Then the frequency drops again and dieseling occurs again. And so on for several cycles of “twitching”.

Harm or benefit

Unlike knocking when rocking the steering wheel, there is nothing dangerous about the engine running unstably after being de-energized. On the contrary, the presence of this effect indirectly confirms the good tightness of the combustion chamber, which indicates the general serviceability of the internal combustion engine. This phenomenon can only occur on carburetor engines, because on injection power plants the fuel supply stops when the ignition is turned off.

Hence the conclusion - the absence of twitching after stopping the unit is not at all a sign of poor condition. By the way, a properly tuned and well-maintained carburetor protects the engine from diesel build-up. This is realized using the electromagnetic valve of the EPH system, which, in good condition, shuts off the supply of fuel to the cylinders when the internal combustion engine is turned off.

Isn't this a glow ignition?

Experienced drivers often replace the concept of diesel engine with glow ignition (KI), which is fundamentally considered incorrect. Elementary differences are revealed by the definition of a short circuit - this is the ignition of the fuel-air mixture from a heated source, which can be:

• Overheated spark plug surface.
• Exhaust valve.
• Nagar.

As has already been determined, the engine shows signs of detonation during shutdown due to self-ignition of the fuel assembly during its compression (the spark plug is de-energized).
Glow ignition implies the presence of deviations precisely when the spark plug is working: heated surfaces or a layer of carbon deposits ignite the mixture earlier than necessary. The consequences of a short circuit are dangerous. It may cause:

• Melting of candles.
• Overheating of pistons.
• Valves melting.

It is noteworthy that the “glow” motors operate stably throughout the entire operating speed range. Stability is explained by the fact that the temperature of a heated source continues to increase and maintain.

Dieseling

This is the name given to the working process in the cylinders of a gasoline engine, which proceeds similarly to the diesel cycle. As mentioned above, detonation occurs when the engine is running under load. This means that it cannot be even at idle. Why doesn't the engine stall with the ignition off?

One of the reasons for this phenomenon is excessive heating of the engine with a high compression ratio in the cylinders. After turning off the ignition, the crankshaft rotates by inertia for a few more seconds until it comes to a complete stop, and the time of each stroke increases. Since the ignition is turned off, there are no new flashes at first.

At some point, the high temperature of the air mixture over an increased period of time leads to such heating of the mixture that it spontaneously, in the absence of a spark, ignites. That is, ignition took place like a diesel engine. The crankshaft received a torque impulse and began to rotate.

However, with an increase in rotation speed, the duration of the compression stroke has decreased, and the mixture does not have time to heat up to the ignition temperature. The flashes stop and the engine stops. But here the compression time increases again, the heated mixture begins to ignite again, and this can continue for some time.

Most often, the engine still stops on its own. If this does not happen, it must be silenced forcibly. To do this, simply engage the gear and release the clutch pedal. With increased load, the motor will finally stall.

Dieseling is generally a harmless process. It does not cause any harm to the engine, although it happens quite rarely. Moreover, this phenomenon indicates that the engine compression is excellent, which means there is no wear on the parts of the connecting rod and piston group.

Briefly about the main thing

After stopping the engine, there can be no detonation - this unstable “jerking” is called dieseling. This phenomenon does not carry anything dangerous in itself. The reason for its appearance is the flow of fuel into the cylinders when the ignition is turned off. It occurs, as a rule, on carburetor engines with a faulty EMC.

Detonation occurs exclusively when the engine is running and is accompanied by a characteristic metallic ringing. It appears when driving at low speeds under load, when starting off, after refueling with low-octane gasoline and due to incorrect setting of the ignition timing on a carburetor engine. On an injection power plant, the engine knock sensor and the ECU are responsible for the latter.

Without exception, all VAZ cars, from model 2101 to modern versions, are equipped with gasoline power plants, which are a higher priority for all automobile manufacturers.

The normal functioning of any gasoline engine is ensured by a number of factors - maintaining the correct proportion of the air-fuel mixture, the quality of gasoline, the appropriate ignition timing, and the condition of the CPG. If at least one of these factors does not correspond, a negative effect such as detonation may occur.

Adjusting engine operation using electronic control

An electronic control unit (ECU), installed in cars with an injection engine, regulates the parameters of the fuel mixture. Using the ECU, the ignition timing is corrected with a forced reduction in the volume of the injected fuel mixture.

The causes of detonation partially disappear, but as a result of such regulation, the power of the power unit is significantly reduced. If the injectors are clogged at a high level, the ECU cannot always perform compensating functions.

Detonation - what is it?

Detonation is simply improper combustion of the mixture. But if measures are not taken in time, then the detonation of a VAZ engine can have strong negative consequences. The peculiarity of this effect lies in the self-ignition of the combustible mixture due to exposure to high temperatures and pressure in the cylinders.

During normal engine operation, combustion of the combustible mixture occurs in three stages.

1. Induction, takes place as the piston approaches top dead center. At this stage, a source of flame begins to appear from a spark, which subsequently forms a flame front, and all this is accompanied by a slight increase in pressure in the combustion chamber.
2. The formation and passage of a flame front through the combustion chamber, as a result of which the bulk of the mixture burns, and this is all accompanied by a sharp increase in pressure and temperature.
3. Burning out of the mixture residues that remained behind the front, as well as those located near the cylinder walls. It is between the transition from the second stage to the third that detonation may occur. The high temperature and pressure that occurs during the second stage leads to rapid chemical reactions in the unburned mixture, causing it to spontaneously ignite. Such combustion occurs very quickly (up to 1200 m/s) and in the form of an explosion, accompanied by the formation of shock waves that are destructive.

Part 3 of 3: Fighting carbon deposits

• fuel additives for engine cleaning;
• high quality fuel.

Step 1: Try Engine Cleaning Supplements

If you have tried all of the above steps and still do not get rid of the problem and the engine does not stall right away, then you probably have severe carbon deposits in your engine.

Carbon deposits can cause an increase in engine compression and create particularly hot spots in the engine's combustion chamber, which can subsequently lead to diesel burn. There are now many different additives on the market designed to clean the engine while it is running.

Following the manufacturer's instructions, mix the additive with the fuel when refueling your vehicle. Then you need to get onto the highway and drive some distance at high speed, while accelerating strongly several times. A fuel cleaning formula can help break down carbon deposits and remove them through the exhaust pipe.

Step 2: Change fuel

Using higher octane fuel can help mitigate the "diesel" problem that you haven't been able to get rid of using other methods. You must understand that this is not a way to get rid of the problem, but a form of proper engine care.

High-octane fuel is more stable and less susceptible to premature ignition from hot carbon deposits in the engine.

Over time, it will become clear to you that refueling with more expensive fuel is too expensive. In addition, the initial impressive effect of using high-octane fuel will diminish over time. To finally solve the problem, a more thorough engine repair may be required.

Let's start with the fact that in this article we do not consider possible problems with the electrical system (ECU or ignition switch), as a result of which the driver is unable to interrupt the spark supply. Next we will talk about the reasons that force the motor to work after the spark has stopped.

Under certain conditions, the fuel-air mixture in a gasoline engine can ignite on its own under the influence of high temperature and pressure. Premature ignition of the charge creates resistance to the upward-moving piston, creating a load on the crankshaft and other elements of the CPG and the crankshaft. The negative side of glow ignition is also the uneven distribution of heat in the combustion chamber, which leads to engine overheating.

In some cases, a phenomenon has been noted where an engine short circuit can occur even after the ignition is turned off. The energy from the self-igniting fuel causes the crankshaft to rotate, causing fuel to continue flowing into the cylinders. Then it heats up again and then spontaneously ignites.

Read in this article

Causes

If we consider this effect only on the engines of VAZ cars, then it can occur on any of them - both an obsolete engine of model 2106, and a modern installation of the same version 2114, etc.

There are certain reasons for VAZ detonation, and they are as follows:

• Incorrect proportions of the combustible mixture. In an overly enriched combustible mixture, after entering the cylinder, due to exposure to high temperatures in remote corners of the combustion chamber, oxidation processes may occur, which are the root cause of detonation;
• Ignition timing violation. As the angle increases, all processes in the cylinders take place even before it approaches TDC. Hence the high pressure and temperature, and the appearance of chemical reactions with part of the mixture.
• Octane number. The lower it is, the higher the likelihood of detonation. This is all explained by the fact that low-octane gasoline is more susceptible to reactions.
• High compression ratio. An increase in this parameter above the norm leads to increased pressure and temperature in the cylinders, which are catalysts for the occurrence of reactions.

All the described factors for the appearance of this effect are the same for all gasoline engines, therefore the reasons for detonation of a carburetor engine are the same as for an injection engine.

Replacing with diesel oil for efficient engine operation

After cleaning, it is necessary to apply oil, which will provide the best lubrication and protection to the parts. For diesel engines, try to choose products with ACEA B4/B5 C3 classification, that is, which are intended only for diesel engines.

The additives are washed so effectively that carbon deposits do not have time to accumulate.

Top Tec 4200 diesel is a high-performance diesel synthetic motor oil obtained by hydrocracking from mineral raw materials, practically does not form soot, and is characterized by a unique combination of a high viscosity index (more than 160 units) and a high degree of fluidity. Which, in turn, allows you to operate the car in all road conditions, even extreme ones, in a wide temperature range from –50 to +40°C.

Thanks to the combination of these properties with good thermal-oxidative stability, the interval between replacements can be up to 20,000 km.

The use of this product helps to extend engine life, save fuel, minimize noise and increase the service life of the exhaust gas aftertreatment system (including DPF particulate filters). Recommended for most models of modern diesel internal combustion engines.

Stabilize viscosity to help oil

When it is not possible to change the oil, use a special additive to stabilize the viscosity characteristics.

By using the Visco-Stabil additive for diesel motor oils, it is possible to stabilize pressure and viscosity indicators in high temperature and cold start modes. Helps increase compression and reduce noise, as a result of which it is especially recommended for use in engines with high mileage.

Thanks to the use of Isko-Stabil B, the density characteristics of the oil are optimized and its waste is prevented. The product is compatible with all types of motor oils (mineral, semi-synthetic, PAO and HC synthetics). Filling into the engine is carried out as needed at the rate of 300 ml of Visco-Stabil product per 5 liters of oil.

Detonation and glow ignition

There are cases when detonation occurs when the ignition of a VAZ-2106 or any other version is turned off. That is, the power plant continues to operate independently even after the spark supply is stopped. Here, too, the process of self-ignition occurs, but it occurs for slightly different reasons. Such ignition occurs from some excessively heated elements of the CPG. This effect is called “glow ignition”, and this is no longer detonation of the VAZ-2106 engine. These two concepts should not be confused as they are completely different.

Recommendations from experienced motorists

In the manufacture of automobile engines, all parts have certain parameters designed for operation in nominal temperature conditions. When an engine detonates, the vehicle is subjected to shock loads that exceed permissible values. Uneven distribution of fuel and oxygen masses leads to unexpected strong explosions.

To identify and prevent cases of detonation, it is recommended to listen to the uniformity of the sounds of the running engine. If unusual tapping or noise is detected, you must stop and turn off the engine. Next, you need to determine the source of the unknown sounds and try to eliminate it.

To avoid devastating consequences, detonation must be constantly monitored. The main thing to remember is that during normal operation there should not be even slight changes in the sound of the motor.

Consequences. Fighting methods

Detonation of a carburetor engine is accompanied by the appearance of a metallic knock, especially under load. Many people perceive it as the “ringing of fingers” of the pistons, but the distinct sound, as if metal is hitting metal, is due to the blast wave.

The consequences of this effect, if no measures are taken, are very serious. Overheating of the component parts can lead to breakdown of the block head. The absence of an oil film, which is destroyed due to the effects of detonation, increases friction and leads to accelerated wear of the CPG elements. And finally, the mechanical impact of the shock wave together with high temperature can cause the piston to burn out, destroy the bridges between the rings, bend the connecting rod, and burn out the valve plates.

Consequences of detonation combustion of the mixture

Valve burnout
Features of injection engines There are several ways to effectively combat this effect on carburetor engines. First of all, when detonation occurs, the fuel should be replaced, especially if the fuel was previously refueled at a station with questionable fuel quality. If the fuel does not cause suspicion, then it is worth checking the ignition and setting a later advance angle by turning the distributor.

The causes of detonation in an injection engine are identical to that of a carburetor, but in addition to metallic ringing, such engines have a number of other signs indicating the occurrence of this effect.

And all because the engine with such a power system is more advanced. Its processes of mixture formation and supply of mixture to the cylinders are controlled by an electronic control unit based on the readings of many sensors. Also, depending on the operating mode of the engine, he also independently selects and sets the advance angle. That is, the driver can no longer set the ignition on his own.

The electronic unit is able to track the occurrence of detonation. For this purpose, all injection engines are equipped with a knock sensor (DS).

Knock sensor

This sensor is capable of detecting the appearance of detonation combustion, and the ECU will take action based on its data. For example, if the cause of detonation of a VAZ-2109 engine equipped with an injection power system is low-quality fuel, and the sensor detects the effect, the ECU will simply reduce the ignition timing and the detonation will stop.

Gas exchange in theory

It’s worth starting with the fact that previously spark plugs were not used to ignite the fuel mixture in the engine cylinders, but there was a special glow tube (head) preheated to a certain temperature. Such a system has long since sunk into oblivion, and today it is used only on low-power diesel engines. Glow ignition was completely replaced by spark ignition, and today it is mistakenly confused with detonation. But the glow type of ignition of the fuel mixture and its detonation are completely different phenomena.

Consequences of incorrect ignition timing

Note that there is a certain relationship between the glow type of ignition and detonation, namely: in most cases, the occurrence of detonation, characterized by an increased thermal load on the parts of the power unit, leads to the occurrence of glow ignition, which is characterized by early ignition of the fuel, which leads to a decrease in power and overheating engine. Glow ignition is also dangerous because the engine can continue to operate even after it is turned off. And if this process is not eliminated in time, the engine may simply fail.

Signs of a malfunctioning knock sensor (DS)

Note that a malfunction of the motor drive can affect the performance of the power plant. The fact is that if the ECU detects that it is not working, it will switch the engine operation to emergency mode, in which the ignition will be delayed in order to completely eliminate the possibility of detonation combustion.

Signs of a malfunction of the VAZ-2110 knock sensor are as follows:

• Unstable engine operation at idle;
• Decrease in engine power performance;
• Increased gasoline consumption;
• Difficulty starting the engine;

In general, everything that is a consequence of late ignition. Signs of a malfunction of the VAZ-2114 knock sensor or any other VAZ injection model are identical.

But such signs can be given not only by the DD, but also by other sensors responsible for the operation of the power system, so it is important to know how to check the knock sensor of the VAZ-2110. Otherwise, you can spend a long time looking for the cause of the motor’s malfunction. Often car owners do not pay attention specifically to the DD, sinning on other elements.

Question answer

Perhaps, after reading hundreds of forums and sifting through a mountain of specialized literature, the reader will still not find the answer to his question. But before you take your car for diagnostics, you can familiarize yourself with the most common questions regarding engine operation. The answers are also given here:

• Q: Could detonation be associated with the appearance of carbon deposits?
• A: In water-cooled engines, carbon deposits form in any case. The thickness of the layer changes all the time, but the controller is needed to adapt to any changing conditions. This is also true for carburetor engines if they are controlled by an ECU.
• Q: How does the glow number of spark plugs affect the appearance of glow ignition?
• A: If you install a spark plug that is “too cold,” you will get carbon deposits on the electrode and on the body. Installing “hot” spark plugs is a more complicated case. If the glow number is less than recommended, then overheating of the spark plug body will not necessarily lead to glow ignition. However, igniting the mixture with hot ceramics is a probable process. In practice, you should also pay attention to the correct installation (see figure).
• Q: Previously, detonation occurred on a hot engine. After changing the gas station everything went away. Perhaps the controller is faulty?
• A: Most likely the knock sensor, its wiring, etc. are faulty. Increase the speed to 3500 rpm - the Check lamp should turn on immediately.

An illustration of the second question is given below:

Errors when installing spark plugs

Perhaps readers will add to the list by leaving intelligent comments and reviews.

Where to look and how to check the knock sensor

In order to check it, you also need to know where the VAZ-2110 knock sensor is located. Everything is simple here; so that it can effectively capture vibrations, it is placed on the cylinder block. Its location largely depends on the design features of the motor itself.

On 8-valve engines it is usually located in the line of sight and is usually easy to get to. Therefore, it is not difficult to determine where the knock sensor is located on a VAZ-2107 (injector). It is installed on the exhaust manifold side and consists of a massive washer with wiring going to it and secured to the engine with a bolt.

But on 16-valve engines, the installation location is slightly different than the location of the knock sensor on the VAZ-2107 (injector). Due to the fact that the block head is much more massive, the sensor is located lower - under the exhaust manifold, so access to it is limited, and often it can only be reached from under the car on an overpass or inspection hole.

And although the location of the motor may differ slightly due to the design of the motor, its connection is always identical. Thus, the connection diagram for the VAZ-2109 knock sensor with an injection engine is the same as on the 2114 model.

Checking the VAZ-2110 knock sensor can be done in two ways.

The first of them implies the presence of a tester switched to measuring resistance (measurement level - up to 2 kOhm).

Checking the knock sensor with a tester

To check, you just need to disconnect the wiring block from the sensor and connect a tester to the sensor contacts. Then you should apply light blows with a wrench to the DD fastening bolt and monitor the readings on the tester display.

After connection, the display will show a certain resistance value of the sensor. At the moment of impact on the bolt, the resistance will increase sharply, but then return to the old value. If this does not happen (the resistance does not rise or does not return), the sensor is faulty and requires replacement.

The second method does not require any equipment and is more effective. To carry it out, you need to start the engine and set the speed to 2000 rpm. Then take an open-end wrench, you can use a small hammer with a metal attachment (if access to the DD is limited) and strike the fastening bolt. If the DD is in good working order, after the impact, the engine speed should drop, since such an impact will be regarded by the sensor as detonation and the ECU, based on its signals, will reduce the ignition angle. After the impact on the bolt stops, the speed should be restored. If this does not happen, the DD is faulty.

Setting the ignition timing yourself

Correctly set ignition timing requires adjustment of the OZ. It is necessary to adjust the ignition angle at idle speed. It should be taken into account that the optimal idle speed is considered to be in the range of 850-900 rpm. The ignition timing angle is also within a certain range from -1 (negative) to +1 (positive) degrees. The degree indicated is the degree relative to TDC.

Most often, a strobe light is used to set the ignition timing. This solution allows for precision installation. If the device is not available, you can also use the control light.

The specified lamp is connected to the positive terminal on the ignition distributor, and is also connected to ground. Next, we will look at the main available methods for setting the ignition using the following example of a domestic “classic”:

Setting up strobe ignition

• the engine must be warmed up until it reaches operating temperature;
• The strobe light is connected to the on-board network;
• unscrew the fixing nut of the ignition distributor-interrupter cover;
• the alarm signal sensor is placed on the high-voltage wire of the first cylinder;
• if there is a vacuum corrector hose, you will need to remove and plug the specified hose;
• the strobe light is directed to the crankshaft pulley;
• the engine starts and idles;
• the distributor body is rotated;
• the position of the breaker-distributor body is fixed so that the pulley mark coincides with the corresponding mark on the timing belt;
• after aligning the marks, the fixing nut is tightened;

Setting the OZ according to the control light

If you use the light bulb ignition method, then you need to turn the engine crankshaft so that the mark on the crankshaft pulley matches the mark on the timing cover. In this case, the slider on the ignition distributor should point to the spark plug wire of the first cylinder.

Next, the distributor lock nut is loosened, after which one wire from the light bulb is connected to the wire that goes to the ignition coil from the distributor. The second wire from the lamp is installed to ground. Then you need to turn on the ignition and rotate the distributor body clockwise until the control lamp stops lighting. After this, you should carefully turn the distributor body back, that is, counterclockwise. Having determined the position at which the light bulb lights up, it is necessary to fix the distributor body in this position. Fixation is done by tightening the distributor nut.

Replacing the sensor

We figured out how to check the knock sensor of a VAZ-2114 or any other model. Please note that this sensor cannot be repaired and if it is faulty, it must be replaced.

Replacing the VAZ-2114 knock sensor is a simple operation, but it can be difficult due to poor access to it (16-valve engines). To change, you just need a new element and an open-end wrench of the appropriate size.

Before unscrewing the mounting bolt, you must first disconnect the block with wires. Then the bolt is unscrewed, the old sensor is removed, and a new one is installed in its place and securely fixed with the same fastener. And only after that the block with wires is connected.

Tapping metal on metal in the front of the car - struts and springs

Car shock absorbers and struts are sources of a certain type of sound. We are talking about tapping on uneven surfaces, crackling noises when the suspension breaks down, and various unpleasant squeaks due to excessive spring wear. There is also a mystical sound that occurs only on small irregularities. It's like tapping two metal rods against each other. In this case, the following diagnostics should be performed:

• jack up the car on the side from which the strange sound is coming;
• remove the wheel to gain full access to the shock absorber system;
• visually inspect the spring, which is most likely the source of this sound;
• find places on the parts that are worn and polished to metal and clean;
• try to tug the spring with your hand to see if it is properly attached;
• check if the spring is hitting the inside of the strut, creating such sounds;
• use the services of a specialist to install new springs or diagnose old ones.

Most likely, you are dealing with springs that refuse to work normally. In this case, you should simply replace the springs on both sides, updating the quality of your car's ride. Most likely, after this the comfort of using the vehicle will become much better. In most cases, old springs sag, lower the car, reduce its ground clearance and contribute to the appearance of a variety of problems, so replacing it definitely won’t hurt.