A serviceable engine, when idling, creates a minimum of vibrations. If the vibrations are strong and are transmitted even to the body, this indicates that some of its components are not working properly. Next, we will look at exactly which malfunctions lead to the appearance of vibrations, and how to fix them.

1 Is the engine to blame - primary diagnostics

Idling is the operation of the engine in neutral or with the clutch disengaged. Therefore, if you notice that engine vibration appears at idle speed, and at the same time it is transmitted to the body, make sure that the reason lies in the engine itself. To do this, simply press the clutch pedal. If the situation has not changed, then the engine is really vibrating. If the vibrations have stopped, problems should be looked for in the gearbox (it does not matter if it is automatic or mechanical) or in the clutch itself.

In this case, it is better to show the car to specialists, since the transmission is a very complex system that must be serviced by professionals. To check the condition of the box yourself, you can drain a small amount of oil and examine it. If there is metal shavings in the oil, and the lubricant itself is cloudy and has a burning smell, there can be no doubt - the gearbox requires serious repair. If nothing like this is found in the oil, the suspicion falls on the clutch.

2 Motor troit - what happens when there is no spark?

The most common problem is motor triplet, i.e. uneven cylinder operation. Why does this situation arise? The reason most often lies in the ignition - a weak or unstable spark in the plug leads to the fact that the combustible mixture does not ignite, i.e. one cylinder stops working for a while. Hence such a term - triplet, i.e. instead of four cylinders (applies to four-cylinder engines), only three work at a time.

Of course, there are situations when several cylinders are unstable at once, as a result, the vibration intensifies even more. Most often, triplet occurs due to a malfunction of one or more candles. Moreover, the candles fail gradually - initially the candle produces a strong spark, but over time it weakens, and then gaps appear. Therefore, beginners usually take a long time to identify the problem. Gradually, the problem progresses - at idle, the body begins to vibrate, and sometimes the steering wheel even shakes. This is also accompanied by a loss of traction, as a result of which dips appear during acceleration, and when driving up a hill, the car begins to twitch. In such cases, you just need to replace the candles.

The candles must be changed every 15-30 thousand kilometers, depending on the make and condition of the car.

If replacing the spark plugs does not help, check the other ignition elements - primarily the high-voltage wires. When one of the wires "breaks through", you can hear a characteristic crackling under the hood, and even see small flashes in the dark. Spark plugs can also cause spark problems. Please note that ignition malfunctions lead to a number of negative consequences - accelerated wear of engine parts and other components. Therefore, it is necessary to eliminate the cause of vibration immediately after its detection.

3 Fastening problems - how to test pillows?

Vibration can be caused by worn-out engine mountings (mountings), or vice versa - too hard (vibration appears after installing new pads). Supports perform two important functions at once:

• serve as elements on which the power unit is attached to the body;
• damping engine vibrations, as a result of which they are practically not transmitted to the body.

It is very easy to distinguish vibration caused by problem airbags, as it does not depend on the operation of the cylinders. Those. the engine can run quite stably. At the same time, at the moment you press the gas pedal and when starting off, vibrations can increase. When accelerating and braking, knocks may even appear. To make sure that the pillows are malfunctioning, you can make a visual diagnosis. You need a partner for this.

One person rocks the car, moving sharply back and forth, and the second observes the movement of the engine under the hood. The motor should tilt slightly to the sides, while the angle of inclination should always be the same. If the power unit, as they say, "dangles", then it is necessary to replace the pillows. I must say that the pillows are recommended to be changed, even if they have no visible damage. After installing the new supports, you need to configure them. Incorrectly adjusted fasteners can also cause vibrations and knocks.

4 When do you need to balance?

If vibrations appeared at idle after repairing the engine, then it is quite possible that they are associated with improper balancing of the crankshaft with a flywheel. The fact is that engine repair usually involves grinding the crankshaft, i.e. the weight of the part changes slightly in different parts of it. To balance this unit, extra grams are drilled in the crankshaft body.

In addition, pistons are usually replaced during engine overhauls. Accordingly, the delicate weight balance can also be disturbed. Therefore, before assembling the motor, specialists also carry out the weight distribution of the piston group. The difference in weight often leads to severe vibration, which is especially noticeable at low revs. Therefore, engine repair can only be trusted by highly qualified specialists who have all the equipment necessary for this.

If vibrations appeared not after repair, but during the operation of the car, this may be caused by the failure of the balancing shafts. I must say that balancing shafts are not installed on all engines, but only on those that are initially prone to vibrations. In particular, three-cylinder car engines have such a shaft. VAZ 1111 and VAZ 1113.

5 Why is it important to install the timing belt correctly?

If vibrations occur after replacing the timing belt, it is possible that it was installed incorrectly. Recall that this is a drive belt that transmits rotation from the crankshaft to the camshaft. Thanks to him, the gas distribution system, i.e. valve, works synchronously with the strokes of the piston system. If the belt is installed incorrectly, for example, there has been a displacement of at least one tooth, the valves begin to open and close at the wrong time.

This leads to the fact that dips appear in the operation of the engine, triplet occurs. Accordingly, at idle, as in the case of a faulty ignition, there is a strong vibration, which is well felt on the steering wheel and the entire body. The problem is solved by correctly installing the belt. Therefore, it is advisable to replace it only at service centers.

6 Fuel supply problems - what are they associated with?

Unstable engine idling is very often associated with a problem in the fuel system. Moreover, there are a huge number of malfunction options. Most often this is a clogged carburetor or injector. For flushing the latter, a special stand is used, which ensures the injection of flushing fluids under a certain pressure.

The carburetor does not need a stand. Its cleaning is carried out using chemistry and compressed air. In parallel with cleaning the carburetor or injector, the operation of the fuel pump is checked, which can also cause unstable engine operation. From time to time, the pump needs to replace gaskets, diaphragms and other elements. Problems in the operation of the fuel pump are often accompanied by the smell of fuel in the cabin.

Vibrations in a diesel engine are often associated with malfunctions of the high pressure fuel pump (high pressure fuel pump). This is a very complex and expensive unit, which is responsible for the following functions:

• injection of the required amount of fuel under high pressure (the amount of fuel is determined by the load on the crankshaft);
• determination of the exact moment of the beginning of fuel injection into the cylinder.

Therefore, in the event of a failure, the injection pump requires complex diagnostics and careful tuning.

7 Other common causes of vibration

Vibrations at idle speed can also occur for other reasons. So, interruptions in the operation of the engine may indicate that low-quality fuel has been poured into the tank or that water has entered it. Vibrations in this case are usually accompanied by high fuel consumption and loss of engine power. To solve this problem, it is necessary to drain low-quality fuel from the tank and fill in good gasoline or diesel fuel. Of course, the vibration will not disappear immediately, as it is necessary to use up the remaining fuel.

If the interruptions in engine operation are not related to the quality of the fuel, you should check the filters - air and gasoline. The air filter can be visually inspected. To do this, unscrew the cover of the casing, take out the filter and look through it at the light. If there is no clearance, the air filter must be replaced.

As for the fuel filter, you need to change it on average every two years or after every 25,000 km. If low-quality fuel is poured into the car, then the filter's service life can be greatly reduced. A clogged fuel filter manifests itself at idle speed and causes acceleration dips. In some cases, at idle, the engine may stall altogether.

In modern cars, especially domestic production, the unstable operation of the power unit at idle speed can be caused by malfunctions of the following sensors:

• DMRV (mass air flow sensor);
• DHX (idle sensor);
• DPDZ (throttle sensor);
• DPRV (camshaft position sensor);
• DPKV (crankshaft position sensor).

To diagnose their work, it is better to contact the service center, which has the equipment necessary for this. Since the sensors cannot be repaired, the malfunction can only be eliminated by replacing them. For this, of course, it is necessary to accurately identify which of the above elements is not working correctly. Please note that if you do not replace the flapping sensor in time, then when it is completely out of order, the car will most likely not even start.

Incorrect operation of the mass air flow sensor may be associated with a depressurization of the air duct. Owners of VAZ cars often face this situation.

Vibrations often occur as a result of excessive load on the generator, i.e. while simultaneously turning on various electrical equipment, such as lighting devices, heated rear window, air conditioning, etc. In this case, the vibration usually disappears after pressing the gas pedal, as the speed of the generator itself increases. If the situation repeats frequently even with a small load on the generator, the generator itself should be diagnosed.

Sometimes vibration can be caused not by the motor, but by some kind of attachment in contact with the body. Examine the engine compartment carefully. If a part in contact with the body is not found, drive the car onto an overpass and inspect it from below. These are, perhaps, all the main reasons why the engine can begin to vibrate at idle. Try to identify and eliminate them when the first symptoms appear. Otherwise, the car may require more complex and expensive repairs over time.

The emergence of vibration processes in a car engine indicates a violation of the coordinated work of its systems and mechanisms. Any vibration has a destructive effect on the moving elements of the power unit, therefore, it is highly discouraged to delay diagnostics and repairs when it occurs.

In this article, we will try to figure out for what reasons vibration can occur in the engine, and also consider methods of eliminating them.

Causes of vibration in a car engine

The processes of converting thermal energy into mechanical energy occurring in the power unit of your car are in any case accompanied by vibration, however, due to the design features of the crank mechanism, we practically do not feel it. But sometimes it happens that the motor begins to vibrate with a greater amplitude than usual, especially at idle. This is already evidence that something is wrong with the engine. There can be dozens of reasons for this behavior of the power unit. But most often in a gasoline engine, vibration occurs due to:

• violations of the valve timing;
• malfunctions in the ignition system;
• power system malfunctions;
• depressurization of the vacuum brake booster;
• malfunctions of control sensors of the electronic engine control unit (oxygen, mass air flow, idle, phases, speed, detonation, throttle position, crankshaft position, first lambda probe, etc.);
• engine suspension malfunctions.

Vibration and gas distribution mechanism

Having found "unhealthy" vibration at idle, the first step is to check the correspondence of the marks on the star of the camshaft (shafts) and on the engine cover. The discrepancy between these marks indicates a displacement of the valve timing. This leads to the fact that the fuel mixture, getting into the cylinders, ignites untimely (sooner or later), and also may not have time to burn completely. As a result, the engine loses power, “eats” more fuel, smokes, “chokes” or stalls at idle.

The displacement of the marks can occur involuntarily due to the stretching of the timing belt, its incorrect tension, or due to their incorrect setting during repair work.

This problem is resolved by aligning the specified marks.

Vibration due to faults in the ignition system

The ignition system is designed to ensure timely ignition of the combustible mixture in the cylinders. If an electric spark occurs earlier or later than the intended moment, or is absent altogether, a process similar to that described above occurs. In other words, the engine troit, shakes, stalls. There may be several reasons for this:

• the spark plugs are faulty, or the plugs have the wrong electrode gap;
• high voltage wires are faulty;
• faulty ignition distributor (distributor).

Checking the ignition system

It is better to start checking with candles. Start the engine and warm it up to operating temperature. Set the minimum idle speed (800-1000 depending on the engine). If vibration appears in this mode, the motor troit, remove the cap of the first spark plug, and analyze how the nature of the operation of the power unit has changed. If it starts to twitch or stall even more, put the cap back on, and repeat the procedure for the other cylinders. This means that everything is in order with this candle and its high-voltage wire.

If, after removing the cap from the spark plug, you find that the engine operating mode has not changed - the cylinder does not work, i.e. the fuel mixture in it does not ignite, which leads to "tripping". The reason for this may be either the candle itself, or a high voltage wire, or a malfunction of the distributor. In any case, you will have to inspect each of these elements. As for the candles and wires, they may have a breakdown, in which part of the electrical energy, breaking through to the "ground", simply leaves. In this case, the spark is either very weak or absent altogether.

You can check the candle as follows. Remove the caps from all candles. Unscrew the required plug from its seat and put the cap on it. Place the spark plug on the valve cover or other surface that has contact with the vehicle earth. Ask the assistant to turn on the ignition and idle the starter. During the rotation of the starter, a steady blue (blue) spark should be observed between the electrodes of the spark plug. If the spark is absent, weak, or has a yellow (orange) color, it has become unusable. But this is all provided that its high-voltage wire and distributor are known to be working.

If vibration occurs in the engine at idle, it is advisable to check all candles for integrity, as well as for carbon deposits and deposits on the electrodes. They can also cause a weak spark. In addition, it is imperative to make sure that the gap between the electrodes of all candles corresponds to the value provided by the vehicle manufacturer.

The high voltage wire can be checked with a multimeter. To do this, it turns on in ohmmeter mode in the range of 20 kΩ. The wire is disconnected from the distributor cover, the cap is removed from it. The multimeter probes are connected to the two ends of the current-carrying conductor. The resistance of the working wire, depending on their type, should be 3-10 kOhm. When checking all high-voltage wires, the difference in their resistance should not exceed 2-4 kOhm.

Now about the malfunctions of the distributor. The first step is to check the correct connection of the wires to its cover. Usually on the distributor and on the wires there are numbers corresponding to a specific cylinder number. If you confuse them, the engine will work unevenly: "sneeze", "troit", shake. The oxidation of the contacts in the distributor cover leads to a similar effect. To disprove or verify this malfunction, open the cover and inspect the contacts. In parallel, pay attention to the condition of the contact carbon (in the center of the cover). Its wear also affects the size and power of the spark. Additionally, diagnose the cover itself. It happens that it also "breaks through", because of which part of the current is lost.

In addition to these reasons, vibration can occur due to excessive load on the generator. This happens when you turn on the heater, headlights, heated rear window at the same time, or, in addition to them, electrical appliances that are not provided for by the design of the car (foglights, subwoofer, heated seats, etc.). An increase in load leads to the fact that the generator, designed to generate a current of a certain magnitude, simply does not cope with its task. As a result, we have a defective spark on the electrodes of the candles.

Power system malfunctions causing vibration

In the power supply system of a gasoline engine, malfunctions can also occur, leading to the occurrence of vibration processes. They all boil down to interruptions in the supply of fuel to the intake manifold, and, as a result, improper formation of the fuel mixture. Most often, idle vibration occurs when a too “lean” fuel mixture enters the cylinders.

An accurate diagnosis of the fuel system can only be carried out with special equipment. This applies to both carburetor and injection engines. It makes no sense to describe possible malfunctions here, since there can be as many of them as you like. Here are just a few common reasons:

• malfunction of the fuel pump;
• clogged fuel filter and fuel line;
• clogging of the coarse filter and fuel jets (for carburetor engines);
• incorrect carburetor adjustment;
• clogged fuel injectors (for injection engines), etc.

Dealing with the causes of vibration, it is advisable to start diagnosing the fuel system only after you are convinced that the ignition system is working. It is better to start the check with the fuel pump and the line, and after making sure that they are working, proceed to the carburetor or injectors.

And here the brakes

It is safe to say that not all car owners can somehow connect the braking system with the power supply system, although often the cause of engine vibration is precisely a malfunction of the brakes. It is not difficult to diagnose this breakdown, but first, let's figure out how these two systems are related.

The fact is that the vacuum brake booster is connected to the engine intake manifold through a check valve and a hose. They serve to create a vacuum in the amplifier. This is due to the rarefaction of air generated in the manifold due to the movement of the pistons. In other words, they simply suck air out of the amplifier. If the check valve or hose is not tight enough, more air enters the manifold, resulting in a "lean" mixture.

Checking their tightness is carried out as follows. With the engine off, press the brake pedal 4-5 times at 1-second intervals. Next time, press and hold the pedal. It shouldn't fail. In this position, start the engine. When the engine starts running, the pedal should move forward slowly. If this does not happen, then there is an air leak somewhere.

Moving on to the engine compartment. We find there a vacuum booster and a place where a hose with a check valve is attached to it. We loosen the fastenings of the clamps that fix the hose to the fitting on the intake manifold and to the valve.

We remove the hose, inspect it. We verify its integrity by purging, closing one of its ends. If there is the slightest air leak, change the hose to a new one. If everything is fine with the hose, remove the check valve from the body of the vacuum amplifier. You can check it with a rubber bulb put on the fitting that enters the body of the vacuum cleaner. Putting the bulb on the fitting, push it down, releasing air through the valve. It should come out freely, but not come back. If you don't have a pear at hand, you can simply blow first into the wide fitting, then into the narrow one. In the first case, the air must pass through, in the second - no. If air flows freely in both directions, the check valve must be replaced.

Control sensor malfunctions

Failure of any of the sensors that send signals to the electronic engine control unit can also cause unstable engine operation. For example, in the event of a malfunction of the lambda probe, mass air flow sensor, speed, idle speed sensor (regulator), throttle position sensor, the ECU will operate in emergency mode, incorrectly forming the fuel mixture. Roughly the same will happen if the phase, knock or crankshaft position sensor breaks down.

It is possible to determine which of the sensors is faulty by reading and decoding the error code, which the electronic controller will definitely determine.

Engine Mount Malfunction

The vibration can also be caused by the engine mount. Most often, the front supports are brought down. Their pillows sag, shrink or, in general, fall apart, which leads to an uneven distribution of engine mass on the supports. The fastening may also simply loosen.

A similar malfunction is diagnosed by examining the condition of the supports and checking their tightness.

Vibration in a diesel engine

Vibration at idle speed can also occur when a diesel engine is running. Everything is much simpler here: no candles, wires, distributors, however, a "shaking" diesel promises more serious problems. The first of them is a malfunction of the high pressure fuel pump, which can only be checked at a special stand, and not every specialist will undertake to repair it. The second possible reason is clogging of the fuel injectors, which can be removed by cleaning, again using special equipment.

It is best to start diagnosing a diesel engine by checking the amount of compression in the cylinders, since it is this that is the key to the stable operation of the engine. Insufficient pressure in the cylinders leads to the fact that the fuel mixture either does not ignite at all, or does not burn completely (at the wrong time).

Be sure to check the marks on the camshaft pulley and engine cover. Incorrect injection angle is the most common cause of unstable diesel operation.

And, of course, do not discount the engine mounts. Their malfunction in any case will affect the behavior of the motor, and more under load than at idle.

In addition, watch a video about one of the causes of vibration at idle:

Idling is the mode of operation of the car engine in neutral gear, when the car is stationary and the gas pedal is not pressed. In this case, the engine does not stall in this mode.

During the operation of the vehicle, the driver may be faced with the fact that vibrations appear at idle speed, etc. It is important to understand that increased vibrations at idle speed are considered a deviation from the norm and are the reason for diagnostics.

Read in this article

Engine vibrations at XX and low rpm: causes and symptoms, diagnostics

First of all, you need to know what can cause engine vibration at idle speed. Firstly, it can be when there is a malfunction in the engine cylinders. In this case, the combustion of the fuel-air mixture in the cylinders is different from normal.

The situation can range from a failure of one or more cylinders to complete cessation of their work. At the same time, in the early stages, triplet is weakly noticeable, usually manifests itself in the form of vibrations at the twentieth century.

The reasons for the engine triplet are:

1. Problems with;
2. Incorrect supply of fuel or air to the cylinder;
3. Clogged air filter;
4. Problems in;
5. Wear and, as a result, engine breakdown;

The triple is manifested in the following:

We also note that vibration can occur in modern cars, especially in winter due to the abundance of electronics and idling loads. Such vibrations are considered normal, they pass quickly (often after the engine warms up). Also in this case, especially in winter, it is advisable to use a higher quality fuel. The air filter may need to be replaced.

As you can see, to prevent vibrations, regardless of whether it is necessary to maintain the cleanliness of the fuel system, the operability of the ignition system, etc.

Sensors, fuel and air filters deserve special attention, you need to adjust the fuel injectors, idle valve, accelerator pedal. It is important to understand that vibrations not eliminated in a timely manner lead to the following negative consequences:

• cracks in the car body;
• gradual loosening of even the most tightly tightened nuts and bolts (which can lead to an emergency);
• premature wear of parts, resulting in, for example, destruction of bearings, seats, fasteners, etc.

We also note that sometimes motorists are faced with such a problem as a drop in speed to 500 rpm. on a warm engine at a rate of 750-900 rpm. As a result, the internal combustion engine begins to vibrate strongly. This indicates a problem with the throttle and sensors (for example).

Also, drivers often deliberately lower idle to save fuel (especially). In this case, the consequences of engine vibrations in the future will lead to repairs, which, at a cost, will overlap all the savings on fuel.

Even while driving, it is important to consider. The fact is that if the vehicle is used improperly, vibrations are also possible. To prevent this from happening, you should adhere to the following rules:

• shifting to the highest gear must be done between peak torque and highest power;
• when vibration appears, it is necessary to switch to a lower gear in order to avoid engine damage;
• if the machine does not pull, you must also downshift, but avoid vibrations.

This approach will avoid premature wear of parts, while ignoring will quickly damage the engine pistons, transmission bearings, clutch basket, liners, etc. Carbon deposits appear on the walls of the cylinder liners and production, due to constant vibration, they begin, beating of the shafts appears.

Let's summarize

As you can see, the causes of engine vibrations at low speeds and idling are dangerous for the car engine and its individual parts. Any vibrations not only impair the operating comfort, but also harm the engine.

It must be remembered that in addition to loose nuts and bolts, the problem of vibrations, which was not solved at the initial stage, ultimately leads to engine breakdown or an emergency on the road.

Only timely fixation of the above signs of vibrations, immediate elimination of the causes, as well as regular technical inspection are the key to the long and safe operation of the internal combustion engine and the entire vehicle.

Read also

Why the engine can vibrate at idle. Failure reasons, diagnostics. Tips and tricks for reducing motor vibration.

Well-coordinated work of all systems and mechanisms of an automobile engine is the guarantee of its longevity. The appearance of vibration processes in the motor indicates that a failure has occurred in its operation. Any vibration has a detrimental effect on the moving elements of the unit. It can also be transmitted to the body and interior, which is even worse. Therefore, if vibrations occur, it is worthwhile to identify and eliminate the problem as soon as possible. In this article, you will learn what causes vibration in a car at idle speed and how to deal with it.

Main reasons

When thermal energy is converted into mechanical energy, which occurs in the power unit of a car, the occurrence of vibration is inevitable. Nevertheless, the driver and passengers do not feel it, thanks to the special design of the crank mechanism. Sometimes the engine starts to vibrate so much that you can even feel it in the cabin. At idle, this is usually the strongest. This vibration indicates that something is wrong with the motor.

There are a lot of problems that cause vibration of the power unit. We will consider the most typical of them:

1. Camshaft timing failure.
2. Ignition system malfunctions.
3. Power system malfunctions.
4. Violation of the sealing of the vacuum brake booster.
5. Malfunctions of control sensors of the ECU (electronic control unit) by the motor.
6. Violation of engine mountings.

Camshaft timing failure

If vibration occurs in the cabin at idle, the first step is to check whether the marks on the camshaft star match the marks on the engine cover. If they do not correspond, then the valve timing has shifted. As a result, getting into the cylinders, the fuel mixture ignites unevenly. In addition, it may not have time to burn completely. This leads to the fact that the engine loses power, starts to consume more fuel, smokes, and sometimes even stalls.

The displacement of marks occurs involuntarily. The main reasons for this are: stretching of the timing belt, incorrect tension, incorrect labeling during repairs. The same problem can occur in a timing chain engine such as the Z22SE. Vibration in the cabin at idle in a car with this power plant occurs due to the unsuccessful design of the chain and the oil nozzle in the timing drive. As a result of the hydraulic tensioner jamming, it ceases to perform its functions, and the chain begins to deform.

In a motor with a timing belt, the problem is solved by combining the above marks, which cannot be said about engines of the Z22SE type. Vibration in the cabin at idle in such power plants is eliminated, as a rule, only by replacing the hydraulic tensioner, and sometimes the entire timing kit.

Ignition system problems

The main task of the ignition system is the timely ignition of the fuel mixture in the cylinders. When an electric spark appears earlier or later than necessary, or is absent altogether, a failure occurs. It manifests itself in about the same way as in the previous case: the motor troit, stalls and vibrates.

The following problems may arise in the ignition system:

1. Malfunctioning spark plugs or increased gap between the electrodes.
2. High-voltage wire breakage.
3. Malfunction of the ignition distributor (distributor).

Checking candles

It is better to start checking the system with candles. First of all, you need to start the engine and warm it up to operating temperature. Then you need to set the minimum idle speed (from 800 to 1000, depending on the type of engine). If the motor is troit and vibrations appear, then you need to check the candles. This is done quite simply - you need to take turns removing the candle caps. If, when the cap is removed, the motor begins to vibrate even more or even stalls, this candle and its high-voltage wire are in good order. Having put everything back in place, you need to check the rest of the candles. If, when removing the cap, the engine operating mode remains unchanged, then the cylinder for which this candle is responsible does not work, that is, the fuel in it does not ignite.

To solve this issue, you need to inspect the candle itself, its high-voltage wire and distributor. A common problem with candles and wires is breakdown, in which part of the electricity simply goes to ground. This is usually accompanied by a subtle spark.

To check the health of the candle, you need:

1. Remove all caps.
2. Unscrew the non-working candle.
3. Put a cap on it.
4. Place the spark plug on a surface that has contact with the vehicle earth (eg valve cover).
5. Ask the assistant to turn on the ignition and idle the starter.
6. Check for spark at the spark plug.

When the starter rotates, a stable bluish spark appears between the electrodes of a working spark plug. If it is absent, or has a yellow tint, then the candle has become unusable. Checking the spark plug takes place only if the wire and distributor are known to be working.

If there is vibration in the cabin at idle, it is advisable to check the serviceability of all candles. In addition to the integrity of the latter, it is important to pay attention to the presence of deposits and carbon deposits on their electrodes. They can also cause a weak spark. It is imperative to make sure that the gap between the electrodes of the spark plugs is equal to that specified by the manufacturer of the machine.

Checking the high voltage wire

The high voltage wire is checked with a multimeter. To do this, you need to turn on the device in ohmmeter mode and set the measurement range at around 20 kOhm. The wire should be disconnected from the distributor cover and remove the cap from it. The probes of the device must be connected to the two ends of the conductor. If the wire is in good condition, then the resistance is 3-10 kOhm, depending on its type. The difference in resistance of all high-voltage wires in the system should not exceed 4 kΩ. The owners of Renault cars often encounter oxidation of high voltage wires. Vibration in the cabin at idle speed, as a rule, disappears after replacing the wires.

Distributor check

Now let's talk about the ignition distributor. If there are doubts about the serviceability of the distributor, first of all you need to check whether the wires are connected to its cover correctly. As a rule, there are numbers on the wires and the distributor that correspond to the cylinder number. If you confuse them, then vibration in the cabin at idle speed, tripping and other malfunctions may occur. Oxidation of the contacts of the distributor cover also often leads to a similar effect. You can check their condition by a simple inspection. In parallel, it is worth paying attention to the integrity of the contact coal located in the center of the lid. If it wears out, the power of the spark may decrease. The cover itself is also worth checking out. The fact is that it can be punctured, which leads to the loss of part of the current.

In addition to the reasons listed, vibration can occur due to excessive load on the generator. This happens when the driver simultaneously turns on many electrical appliances (stove, headlights, heated rear window, heated seat, and so on). With an increase in the load, the generator, which is designed to generate a certain amount of electric current, simply does not cope with the task at hand. As a result, the spark on the electrodes of the candles is defective.

Power system malfunctions

As the reviews show, vibration in the cabin at idle is often associated with malfunctions of the power system. They all boil down to an uneven supply of fuel to the intake manifold, which leads to improper formation of the fuel mixture. In most cases, engine vibration at idle occurs due to the depletion of the mixture entering the cylinders.

It is possible to carry out an accurate diagnosis of this system only with the presence of special devices. This applies not only to carburetor, but also to injection engines.

The main malfunctions of the fuel system that lead to vibration processes in the engine:

1. Breakdown of the pump.
2. Clogged line and fuel filter.
3. Clogged nozzles (for carburetor engines) and coarse filter.
4. Clogged injectors (for injection engines).
5. Incorrect carburetor adjustment.

All this can lead to vibration in the cabin when idling. The causes of the malfunction should be looked for in the fuel system only when there is 100% confidence in the performance of the ignition system. It is recommended to start the check with the fuel pump and the line, and then proceed to diagnostics of the carburetor or injectors.

Breakage of the vacuum brake booster

As practice shows, not all car owners can associate the braking system with engine vibrations. In fact, brake failure often becomes the cause of vibration processes. Before we find out how such a breakdown is diagnosed, let's figure out its origin.

The vacuum brake booster is connected to the intake manifold of the engine through a check valve and a hose. The last two elements are designed to create a vacuum in the amplifier. This is due to the discharging of the air generated in the intake manifold when the pistons move. Simply put, a check valve sucks air out of the amplifier. If the tightness of the valve or hose is broken, then more air enters the manifold than is necessary. This leads to a leaner fuel mixture.

Diagnostics of the vacuum brake booster

It is quite easy to check the tightness of the system. To begin with, with the engine off, you need to press the brake pedal 4-5 times with an interval of one second. At first it will fail, but after a few clicks it will stop. Then you need to press the pedal and, without releasing it, start the engine. When the engine is turned on, the brake should move forward slowly. If he did not do this, then there is an air leak in the system.

After making sure that the vibration is caused precisely by the brake booster, you need to inspect the air hose. To do this, it is recommended to remove it by loosening the clamps securing it to the intake manifold and valve. It is best to check the integrity of the hose with a blowdown. If the slightest air leak is found, it must be replaced with a new one.

If everything is in order with the hose, then you need to check the serviceability of the check valve by removing it from the body of the vacuum amplifier. To do this, it is recommended to use a rubber bulb put on the fitting that goes into the body of the vacuum cleaner. Pressing on it, you need to release air through the valve. If everything is in order with the valve, the air will freely come out and not come back. In the absence of a pear, you can simply blow into the wide fitting, and then into the narrow one. In the first case, air should pass freely, and in the second, it should not pass at all. If a check valve is found to be faulty, it should be replaced.

Malfunction of ECU control sensors

Due to the failure of one of the sensors responsible for sending signals to the electronic control unit, the motor may start to work unstably. In the event of a breakdown of the lambda probe, fuel flow sensor, idle speed regulator, throttle sensor and other elements, the ECU works in emergency mode, incorrectly forming the fuel mixture. To determine which of the sensors has broken down, you need to read and decipher the error code, which is determined using the electronic controller.

Motor suspension malfunction

The causes of vibration in the cabin at idle speed can relate to completely different parts of the engine compartment. Sometimes the problem lies in the motor suspension. As a rule, the front supports are brought down. Due to drying out, subsidence, or even complete deformation of the pillows, the engine mass is unevenly distributed between the supports. Sometimes the reason lies in the weakening of the suspension mountings. Diagnostics of this problem is carried out by external inspection of the supports and checking the condition of their tightenings.

Vibration in a diesel engine

As practice and owner reviews show, vibration in the cabin at idle speed can also occur on diesel cars. On the one hand, everything is much simpler here - no wires, candles and distributors. However, on the other hand, the vibration of a diesel engine is associated with more serious malfunctions. The first and most common of these is a breakdown of the high pressure fuel pump. You can check its suitability for work only at a special stand, and not every auto mechanic will undertake the repair of the unit. A second common problem is fuel injector plugging. It is eliminated by cleaning with special equipment.

If on a diesel car there are vibrations in the cabin at idle, it is recommended to start diagnostics by checking the compression in the cylinders. It is the key to normal and stable operation of the power plant. Due to insufficient pressure in the cylinders, the fuel mixture either does not ignite at all, or does not completely burn out.

Among other things, when diagnosing a diesel engine in order to identify the causes of vibration, it does not hurt to check the marks on the engine cover and the camshaft pulley. Often, the unstable operation of a diesel engine is associated precisely with an incorrect injection angle.

Don't forget about the motor suspension as well. As with the petrol powertrain, stretched mountings and dry airbags can cause engine malfunctions. By the way, they appear even stronger under load than at idle.

Conclusion

Today we have examined the main causes of vibration in the cabin at idle speed. Finally, it is worth noting that a car consists of a huge number of mechanisms, the failure of which, directly or indirectly, can affect the operation of the motor. Sometimes drivers, having rechecked the performance of all the systems discussed above, still do not get rid of the problem. This happens especially often among the owners of the Chevrolet Lacetti car. Vibration in the cabin at idle speed is then a more serious problem and requires professional intervention.

The components of any car have a certain mileage, after which they stop working in an ideal way, and they need to be replaced. The car consists of hundreds of parts, and it is simply impossible to keep track of them all. The beginner driver tries not to get under the hood, inspect the suspension, or go into the technical details of the car at all until one of the components fails. This position is incorrect, and there are a number of problems that you can diagnose and fix yourself before serious malfunctions occur.

It is quite simple to realize that there are some problems in the car, and most often this is indicated by the indicators on the instrument panel. However, there are other indicators as well. One of them is shaking the car when the engine is running - at idle, while driving or accelerating. If a similar problem occurs, it may be related to the suspension, engine, untimely maintenance and replacement of consumables, as well as other malfunctions. In this article, we will look at why the car shakes in different situations, and what you can do to fix the problem.

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If you notice that the car began to behave strangely at traffic lights or immediately after starting the engine, that is, the body shakes when the engine is running differently than before, you should fix the problem as soon as possible. Most often, in this way, the car works with one of the following malfunctions:

• The engine is having trouble burning fuel. The body of the car will shake if the process is uneven in the combustion chambers. Because of this, the speed of the car rises and falls unexpectedly and uncontrollably from the driver's side, which can lead to shaking of the car at idle speed. To determine the malfunction, you will have to use diagnostic equipment that can indicate a specific error that prevents the stable operation of the engine. In this situation, there can be a lot of causes of malfunctions - from improper operation of the fuel pump to or incorrect operation of sensors.
• The supports do not support the engine. If they are out of order - the engine mounts are broken, bent or loosened, then its vibration will be transmitted directly to the car body, which will lead to its shaking at idle.

It is worth noting that the reasons that lead to shaking of the car at idle speed are also manifested when the car is moving.

The most unpleasant and dangerous thing is when the car shakes while accelerating. Often, shaking can only occur when the revs are increased at high speed. For example, a car can shake at speeds of 80 kilometers per hour or higher, which is especially dangerous. If your car shakes when accelerating, check the following points:

• Suitability for the transmission filter. On a car with an automatic transmission, a clogged filter leads to jolting during acceleration, which is especially noticeable at high speeds. If the filter is dirty, it must be replaced.
• Gearbox oil level. Another reason that causes the engine to vibrate during acceleration is the insufficient oil level in the automatic transmission. This problem is easy to diagnose on another basis: when accelerating a car with a lack of oil in the gearbox, you can note jerks and a decline in dynamics when you press the accelerator pedal.
• Problems with the driveshaft. If the cardan joint on the car is worn out, then vibration will be observed when the car accelerates. It is especially noticeable when accelerating the car from a standstill, when the engine has to spin the propeller shaft from idle. If the cardan joint is worn out, it is necessary to urgently contact a service center or replace it yourself, as it can lead to malfunction of the entire cardan joint, which will cause the car to fail and high repair costs.

From the faults sounded above, it is easy to conclude that if a car with a manual gearbox shakes during acceleration, then the propeller shaft is most likely to blame. On cars with an automatic transmission, you should also look at the consumables in it.

The most difficult problem to troubleshoot is when the vehicle shakes at speed. This problem is most common, and it can be very disruptive to the driver, given that vibrations are constantly being sent to the steering wheel, thereby putting pressure on the muscles of the motorist's arms. If the car shakes at speed, the following components of the car should be checked:

• Shock absorbers and suspension struts. If the shock absorbers and struts of the machine are worn out, it will swing violently from side to side from every bump in the road. When driving off-road, in this case, the shaking becomes simply unbearable, and due to the constant "jumping" of the machine, other components may fail. In this situation, the worn out shock absorbers and struts should be replaced. It is also worth noting that the support bearing of the strut can become the cause of vibration - it is also important to check it and replace it if necessary.
• Ball joints. Due to the movement of the car on bad roads, the ball joints can become unusable, which will lead to increased vibration due to the occurrence of backlash. It should be noted that the service life of the ball joints is indicated for each car in the passport. Moreover, if you operate a European car, then you should make an allowance for the roads of not the best quality in Russia and replace the ball joints more often than the car manufacturer recommends.
• Wheels. Wheel imbalance results in strong vibrations when driving. Contact your tire dealer to check if the wheels are properly balanced.
• Tie rod ends. If the steering rack does not keep the car level on the road, due to play in the steering tip, vibration will be observed when driving.

Do not delay with car repair if there is shaking when driving, idling or accelerating. Any of the above malfunctions can lead to serious damage to the car. Also, problems can cause an accident.