The car jerks when driving: causes and ways to eliminate them

The phenomenon, which car enthusiasts call jerking, occurs due to a sudden change in the crankshaft speed when the gas pedal is in a stable pressed position. If suddenly a VAZ 2110 jerks while driving, this causes anxiety and concern to the car owner.

We need to do something urgently, but first we need to understand the reason. We will talk about some features of jerks and signals that help you understand why they occur.

During the start

Most often, when starting from a standstill, the highest stage of the jerk is observed - failure, that is, a very significant delay in the engine’s response to the pressed gas pedal. It happens that the engine stalls. It’s especially unpleasant when you’re standing, for example, in front of a traffic light, and someone behind you is already honking, and you’re frantically starting the car again.

A jerk when starting off occurs when the ECU (electronic control unit) gives a signal to start opening the throttle valve, that is, when transitioning from the XX mode to the driving mode.

Throttle position sensor

Throttle position sensor

IN THIS WAY, THE QUANTITY OF FUEL SUPPLY THROUGH THE INJECTORS SHOULD INCREASE, WHICH DOES NOT OCCUR WHEN THE PRESSURE IS INSUFFICIENT IN THE FUEL LINE.

Potential culprits for the car moving jerkily when starting off:

1. fuel pump , which is about to completely fail. This is evidenced by its peculiar periodic “howling” or an increase in its noise. The pump on an injection engine is listened to even before the engine itself is started - it is turned on initially from the battery, starting to pump fuel before turning on the starter. It is located inside the gas tank, so it becomes almost inaudible once the engine is running. In carburetor cars, the fuel pump is under the hood, you can hear it even when the engine is running;
2. The fuel pump mesh is clogged with foreign particles that enter the gas tank along with low-quality gasoline at the gas station, or are formed in the tank itself due to condensation. This is why the gas tank should be flushed periodically;
3. fuel filter , which is located under the hood. It also needs to be changed periodically;
4. pressure regulator To replace it, you will need to remove and disassemble the fuel pump.

The first step is to check what pressure the fuel supply system produces. The check is carried out using a pressure gauge. It connects to a fitting located on the fuel rail (under the hood). We cannot give uniform readings, since it is different on different engines.

For some, a pressure below 325 kPa can be considered normal, while for others it is 400 kPa. That is, you need to look specifically at your instruction manual.

Engine power system

If the pressure gauge readings are too high, it means there is a malfunction in the fuel pressure regulator. If the readings are too low (less than 284 or 364 kPa, again, depending on the engine), replacing the fuel filter will help.

When does this happen

Almost every car enthusiast who has logged more than tens of thousands of kilometers has encountered such a problem as uneven driving of the car, or, in popular parlance, the car simply jerks in some operating modes.

The car jerking can be as follows:

• the beginning of the movement;
• at low speeds;
• with increasing speed;
• at high speeds;
• in all modes at once.

Moreover, it is worth noting that such a malfunction occurs not only on an old car; a new car is also capable of twitching.

It is impossible to say that the cause of uneven running is only a certain part of the car and that it is unique to a specific brand of car.

Based on reviews from car owners, we can conclude that this problem occurs with absolutely any vehicle - an old VAZ “Seven” or a new “Japanese”.

The appearance of uneven movement of the car not only irritates the driver, but can also cause an accident, because at the right moment the car, instead of accelerating, will begin to twitch.

Let's try to figure out in detail what can cause the car to jerk while moving. But to do this, you first need to understand how everything happens.

Why does the VAZ-2112 injector twitch when accelerating: symptoms and treatment

More than once, drivers encounter a problem when a VAZ-2112 begins to stall and twitch when accelerating. What is this connected with? The reason that unites all the factors remains the wrong gasoline mixture or its poor quality.

The video shows symptoms and treatment methods when the car jerks:

A front-wheel drive car of the VAZ family is considered.

Quick diagnostics

So, the car is started, the speed is turned on, the clutch is slowly released, and the engine speed gradually increases.

But instead of smoothly starting from a stop and starting to pick up speed, the car begins to jerk - the speed fluctuates, the speed either increases or drops sharply, despite pressing the accelerator pedal.

This can continue until either the twitching goes away on its own and the car begins to confidently gain momentum, or until the engine stalls.

It happens that the car starts moving quite safely, but as soon as the revolutions increase to 2000-2500, uneven movement begins, accompanied by sharp changes in engine operation, as well as in the speed of movement.

The same situation can be observed when reaching medium modes, that is, the engine reaches a certain speed level, after which twitching begins.

It happens that the car starts to jerk every time you change gears.

It is not necessary that uneven running occurs only under certain conditions.

It also happens that the car jerks spontaneously, without any frequency or conditions. That is, the car can jerk just once, in any mode, and then move normally for quite a long time.

Or the car was working normally, but suddenly began to twitch sharply, and this trouble no longer goes away.

In general, there are a lot of options, but one fact remains - the car has an uneven ride, and it is advisable to eliminate it as quickly as possible before the problem gets worse.

The first thing to do is determine under what conditions the twitching occurs. The easiest way to do this is while moving.

You should drive onto a flat section of the road where there is no traffic and start testing.

At first, just get moving, then gradually increase the speed, remembering the behavior of the car and watching the dashboard.

And this must be done until the engine reaches high speeds.

Afterwards, you will need to run the test again to make sure that the conditions for the appearance of twitching are determined correctly. And only after that you can start looking for the reason.

A summary table of the reasons why the car jerks for different types of motors for quick diagnosis.

* applies only to diesel engines that have a Common Rail injection system.

** applies to vehicles equipped with direct injection engines and 6th generation LPG with liquid gas injection installed on them.

*** for cars with an injection system equipped with an electronic e-gas pedal.

**** for carburetors of cars with an electronic ignition system.

VAZ 2110 injector 8 valves twitches while driving

The car begins to twitch when the crankshaft rotation speed changes sharply, and this happens even when the gas pedal is in its normal state. Of course, such symptoms will cause discomfort for any driver. And before you do anything, you need to identify the cause of the problem.

At the start

At the very beginning of the movement, such problems can begin, and here they will be the biggest jerks. That is, the engine seems to be late in responding to the pressed gas pedal. It may even stall completely, this will happen if the control unit gives a signal to the throttle valve to open.

And there are reasons for this:

1. The fuel pump is running low and it begins to hum or make noise. It is necessary to listen to the engine on the injector before starting; it cannot be heard when the engine is running, since it is located in the fuel tank. On the carburetor, the pump is located under the hood, so it can be heard even when the engine is running.
2. There is a special mesh on the fuel pump that periodically gets clogged, in which case you need to flush the gas tank or change this mesh.
3. The fuel filter needs to be changed, also after a certain period of time.
4. The pressure regulator may fail; it is located in the fuel pump; it is disassembled and the regulator is replaced.

Of course, at the very beginning it is worth checking the pressure in the fuel supply system; a pressure gauge is used for this. It must be connected to the fitting on the fuel system and watch the indicators of the device. Full readings cannot be shown, as they will be different on different engines. One thing we can say is that readings above one are not very good. The dynamics of the device readings can be found in the car manual; it states what the readings should be during normal operation of the car.

But the readings can be too high and here you can immediately answer that the reason for this is the pressure regulator, but it is better to replace it immediately; repairs are not practical here.

When driving

Here, too, not everyone will like it when the car starts to twitch in motion. There may also be a dangerous situation on the road when another vehicle is overtaken and at that moment a failure occurs.

There are also a number of reasons for this, but the above symptoms should not be dismissed:

• On a carburetor car this can happen if the ignition is set to early. This can be easily checked, accelerate immediately at 4 speeds to 50 km/h and at the same time brake sharply, detonation should be no more than 2 seconds, then everything is in order.
• In injection engines, everything rests with the car’s electrics; here jerks can occur if the mixture is too lean. But this can only be checked by specialists during diagnosis.

Cold jerks

Some VAZ 2110 drivers say that the jerking starts when it’s cold, and when the car warms up, they disappear. The most important reason is a lean mixture and therefore air is sucked in at idle. But it is possible that one of the sensors has failed.

If such jerks begin to repeat periodically, whether idling or while driving, you need to check:

• Candles, when they are heavily sooted, they lose contact with the wires, and this needs to be corrected urgently. They should be replaced or the contacts should be cleaned and secured.
• High-voltage wires should be checked with a multimeter, and if they have lost their appearance, it is best to completely replace them.
• The ignition coil, here you need to check the armored wires and the ignition module itself. But the test should be carried out with rubber gloves, otherwise you may get an electric shock.
• The timing belt often jumps several teeth and jerking may occur when running cold. First of all, you should check the marks, and if the belt has slipped, you need to remove it and install it as expected.
• Be sure to check all the sensors on the car; if there are faulty ones, then urgently replace them.
• The filter is checked first, because the air and fuel filters are responsible for supplying a clean mixture to the car engine. Here, fuel consumption immediately increases and they need to be changed after a certain period of time.

But there are cases when everything has been checked and what needs to be fixed, but the problem does not disappear, in this situation you need to rebuild the engine, the problem may be in it.

1. On fuel-injected cars, fuel injectors often become clogged; in this case, it is better to diagnose the car.
2. Of course, you shouldn’t miss the fact that the car was filled with low-quality fuel, and these twitching and jerking can occur precisely because of this; it’s also worth checking the car’s fuel system right away.

Car jerking at low speeds

This problem often occurs when driving at low speeds at low engine speeds.

Checking the engine power system

Often the reason for the car twitching at low speeds is the power system, or rather, a malfunction in its operation.

When starting to move, the required amount of fuel simply does not enter the cylinders; the car is unable to produce the required power to evenly operate the transmission.

At the same time, transmission resistance leads to uneven running.

When jerking occurs at low speeds, first of all you should check all the elements related to the power system, and it makes no difference what kind of system it is - carburetor, injection or diesel.

It is recommended to immediately check the condition of all pipes. Depressurization of the system almost always leads to air being sucked in, which leads to fuel starvation of the engine.

And only after checking the condition of the pipelines can you proceed to the remaining elements of the system, which will be discussed below.

Ignition system

Also, the cause of jerking at low speeds can be the ignition system, especially for injection cars, where the entire operation of the system is controlled and regulated by an electronic unit.

A malfunction of one of the sensors can easily cause the machine to twitch.

Diagnostics using ODB-2 scanner

Since there are many reasons for the malfunction, first of all it is worth carrying out a comprehensive diagnosis of the car. This can be done most quickly using an ODB2 scanner.

Scan Tool Pro Black Edition

A special feature of Scan Tool Pro is the diagnosis of not only the engine, but also other vehicle components (gearbox, transmission, abs, etc.). After reading the errors, you will most likely know exactly the cause of the malfunction (problem in the pump, pressure regulator, lean fuel mixture, malfunction of one of the sensors), after which you should first pay attention to this element. The scanner is compatible with most models of the domestic automobile industry since 1993 and is designed specifically for the CIS - error codes with their interpretation are displayed in Russian.

At high speeds

But the jerking of the car at high speeds is more related to the ignition system.

In a normally operating engine, the ignition system automatically adjusts to certain conditions by changing the ignition timing.

That is, when necessary, the ignition becomes either a little early or late.

A malfunction in the automatic ignition will cause twitching.

Do not forget that the cause of uneven movement will be not only a malfunction of the system, but also the failure of one of its elements.

And these are only the reasons that can arise with the engine, without affecting the transmission.

You need to immediately narrow the search for identifying the reasons for the car twitching to two engine systems - fuel and ignition, but you should not discount the transmission.

Main reasons

General view of engine 2112 16 valves

There are not many reasons why a car may twitch during acceleration, but motorists should know them. So, let's look at what problems contribute to this effect appearing :

• Poor quality gasoline.
• The problem is in the fuel pump or fuel system.
• Failure of the mass air flow sensor.
• Damage associated with the throttle valve.
• The malfunction is hidden in the ignition.
• The fault lies in the ECU.

Is it due to the fuel filter?

So, it has been determined that the car jerks only under certain conditions. The fuel system pipes are all normal, but it is believed that the cause lies in the fuel system.

This means that the filters need to be checked next. Often it is because of them that this malfunction appears.

The task of any filter element in the fuel system is to clean the fuel from impurities, but at the same time, these impurities do not disappear anywhere, they remain in the filter itself.

Over time, it becomes so clogged with impurities and dirt that its throughput drops, and greatly.

As a result, the fuel pump pumps as expected, but the fuel does not have time to pass through the filter elements and the engine begins to “starve”, accompanied by the car jerking. There is only one way out here - .

Carburetor cars

If you take into account a carburetor car, then the number of filters it has is 2-3 pieces, but one of them, the usual mesh on the fuel receiver, can be practically discounted.

This mesh is aimed only at catching large particles, so it is practically incapable of becoming clogged to such an extent that it stops the flow of fuel in the required quantity.

But the second filter, usually located in the pipelines leading to the fuel pump, is worth checking.

This filter is designed to catch smaller particles and is not difficult to clog.

The third filter is not available on all carbureted vehicles and is usually located at the fuel inlet to the carburetor. It is also a regular mesh, but only fine.

This filter itself is small, so it often gets clogged.

Older machines had another filter installed - a coarse filter, also known as a sediment filter.

The design of this filter is such that it is not capable of becoming clogged to such an extent that it will not allow fuel to pass through. But this filter will subsequently cause rapid clogging of the fine filter.

If this filter accumulates a large amount of debris and dirt, then eventually it will not begin to clean the fuel from impurities, but, on the contrary, will begin to add them.

Injection car filters

Most modern injection cars are also equipped with three filters.

• The first of them is a mesh for catching large particles installed in the neck of the tank. This mesh is clearly not the cause of the twitching.
• The second filter is located on the fuel pump installed in the tank. This filter is also often a mesh, only with smaller cells; its task is to prevent large debris from entering the fuel pump. It is also unlikely that it can cause a lack of fuel.

But the third filter, a fine filter, is located behind the fuel pump and is quite capable of becoming clogged to such an extent that the pump cannot push the required amount of fuel through it.

On more modern cars, there may be additional filters, which can also cause the car to twitch.

Cold jerks

Some VAZ 2110 drivers say that the jerking starts when it’s cold, and when the car warms up, they disappear.
The most important reason is a lean mixture and therefore air is sucked in at idle. But it is possible that one of the sensors has failed. If such jerks begin to repeat periodically, whether idling or while driving, you need to check:

• Candles, when they are heavily sooted, they lose contact with the wires, and this needs to be corrected urgently. They should be replaced or the contacts should be cleaned and secured.
• High-voltage wires should be checked with a multimeter, and if they have lost their appearance, it is best to completely replace them.
• The ignition coil, here you need to check the armored wires and the ignition module itself. But the test should be carried out with rubber gloves, otherwise you may get an electric shock.
• The timing belt often jumps several teeth and jerking may occur when running cold. First of all, you should check the marks, and if the belt has slipped, you need to remove it and install it as expected.
• Be sure to check all the sensors on the car; if there are faulty ones, then urgently replace them.
• The filter is checked first, because the air and fuel filters are responsible for supplying a clean mixture to the car engine. Here, fuel consumption immediately increases and they need to be changed after a certain period of time.

But there are cases when everything has been checked and what needs to be fixed, but the problem does not disappear, in this situation you need to rebuild the engine, the problem may be in it.

1. On fuel-injected cars, fuel injectors often become clogged; in this case, it is better to diagnose the car.
2. Of course, you shouldn’t miss the fact that the car was filled with low-quality fuel, and these twitching and jerking can occur precisely because of this; it’s also worth checking the car’s fuel system right away.

And in conclusion, we can say that only high-quality fuel should be poured into the car and in proven places. After all, low-quality fuel can damage all systems in a car. In this case, you can end up with expensive car repairs.

Another piece of advice is to change all components and parts on time, and also periodically carry out diagnostics of the car and the engine separately. Troubles can happen to any car, but the main thing is to find the cause and fix the problem in time, because this is safety on the road.

Source

Other elements of the fuel system

Now on to other elements of the fuel system.

Fuel pump.

The next culprit for uneven running may be the fuel pump.

In carburetor cars.

A mechanically driven diaphragm fuel pump is often used here.

So, even a small rupture of the membrane will cause the pump’s performance to drop sharply.

The pump valves may also be to blame. They can easily break the sealing of the device’s chambers, which leads to a drop in fuel supply.

Injection car.

The fuel pump can also cause jerking. On such cars, since the pump is located in the tank, it is electrically driven.

A decrease in device performance leads to the problem described in this article. Here you need to consider a specific case separately.

Now directly about the carburetor.

Because of this, uneven running of the car is also possible. Often such a malfunction occurs due to severe clogging. Debris and dirt can block channels, clog jets, etc.

Sometimes the reason lies in the accelerator pump. A diaphragm accelerator pump is installed on carburetors, the task of which is to increase the fuel supply when the gas pedal is sharply pressed.

But if the membrane is torn, then the accelerator pump will not be able to increase the supply of gasoline, and hence fuel starvation.

Injectors.

For injectors, the fuel injectors are checked next. Violation of their performance leads to jerking of the car.

Injectors need to be cleaned periodically, in principle, like everything else.

Also, in an injection car, the functionality of all sensors involved in the operation of the power system is checked, and then the electronic control unit is checked.

What to do if the car stalls when accelerating?

Let's look at the following positions:

1. Air filter. A dirty air filter reduces the air supply to create a fuel-air mixture - a lean mixture leads to a drop in engine power and increased fuel consumption. The quality of the air filter material also affects engine performance - don’t go cheap. To check your air filter, open the hood, remove the filter element from the housing and assess the condition. If you can already plant potatoes on it, change it urgently.
2. Spark plug. They may well be excessively worn or dirty, if the engine does not pull because of them - replace the spark plugs, this is a relatively inexpensive option for troubleshooting. However, it should be borne in mind that soot, oil or brake fluid contamination is not normal, and the reason for this is not so much in the spark plugs as in the rest of the engine components.
3. Fuel. Remember where you last refueled - perhaps it was a new gas station, or one whose fuel you had no experience using before - it is quite possible that the problem is the low quality of gasoline. Along with a decrease in torque, low-quality fuel causes instability in engine speed, difficulty starting and some other problems - depending on how bad the fuel is and what model of car.
4. Fuel filter. Just like an air filter, it can cause a loss of engine power, the physics of the process here is similar to an air filter - if in the case described above the fuel did not burn completely due to lack of air, then in the case of a dirty fuel filter, on the contrary, an insufficient amount of fuel is supplied. The problem is solved by replacing the fuel filter.

Let's go through the ignition system

The first thing that is checked in this system is the candles.

There have been cases when a car enthusiast replaced old spark plugs with new, and expensive ones at that, and ended up getting irritated due to the car jerking. But since the candles were new, he did not bother with them, but looked for a different reason.

This problem often occurs due to incompatibility of the spark plugs with the engine.

But their long-term use gives the same result. The spark plugs may fail, there will be gaps in their operation, and as a result, the fuel will not ignite well and may not burn completely.

In general, if the fuel system test fails, the next thing to check is the spark plugs. In this case, the candles themselves can suggest the cause of the malfunction.

At home, you should immediately check the gap on unscrewed spark plugs. Failure to do so will result in disruption of sparking. Then the spark plug is checked for sparking.

In a normally working spark plug, the spark should be powerful, purple in color and there should be no gaps in its appearance.

A faded orange spark, and even with gaps, will signal a malfunction of the spark plug or other element of the system.

Soot on the candle will tell you where the cause is hidden. If there is black carbon deposits on it, then either the ignition on the car is broken, or the mixture formation in the fuel system is disrupted, and this can already cause the car to jerk.

But you should not immediately, having determined that there are gaps and the spark does not correspond to the norm, blame the spark plugs for everything. It is quite possible that a weak spark is a consequence of a faulty connection in the system wiring or failure of one of the ignition elements.

Therefore, the second is to check all the wiring of the system for breaks, oxidation of contacts, and the presence of breakdown. And only after this the remaining elements are checked - the coil, the distributor, the switch.

At the start

At the very beginning of the movement, such problems can begin, and here they will be the biggest jerks.
That is, the engine seems to be late in responding to the pressed gas pedal. It may even stall completely, this will happen if the control unit gives a signal to the throttle valve to open. And there are reasons for this:

1. The fuel pump is running low and it begins to hum or make noise. It is necessary to listen to the engine on the injector before starting; it cannot be heard when the engine is running, since it is located in the fuel tank. On the carburetor, the pump is located under the hood, so it can be heard even when the engine is running.
2. There is a special mesh on the fuel pump that periodically gets clogged, in which case you need to flush the gas tank or change this mesh.
3. The fuel filter needs to be changed, also after a certain period of time.
4. The pressure regulator may fail; it is located in the fuel pump; it is disassembled and the regulator is replaced.

Of course, at the very beginning it is worth checking the pressure in the fuel supply system; a pressure gauge is used for this. It must be connected to the fitting on the fuel system and watch the indicators of the device. Full readings cannot be shown, as they will be different on different engines. One thing we can say is that readings above one are not very good. The dynamics of the device readings can be found in the car manual; it states what the readings should be during normal operation of the car.

But the readings can be too high and here you can immediately answer that the reason for this is the pressure regulator, but it is better to replace it immediately; repairs are not practical here.

About the transmission

Now a few words about the transmission, since it can also cause jerks when driving.

As you know, cars use manual and automatic transmissions.

As for a manual transmission, the gearbox and everything that follows it cannot cause jerking.

A manual transmission is a fairly simple design, and if it already breaks, it breaks specifically, and not creating jerks.

But the clutch can cause jerking. If it is heavily worn, in particular the driven disk, or “slips,” then the car easily begins to twitch.

But as a rule, jerking and twitching with such malfunctions occurs during gear shifting.

In automatic transmissions, the cause of the jerking is the gearbox itself.

It is very dependent on the quantity and quality of oil, so a lack of oil or its foaming can easily cause uneven running of the car.

You can measure the oil level in the automatic transmission using a dipstick.

Or without.

It all depends on the design of the automatic transmission.

How to measure the oil level in an automatic transmission.

Significant wear of the automatic transmission, as well as clogged oil channels, also causes the car to jerk at all speeds.

Prevention is better than repair

But first of all, it is necessary to find an answer to the question of why the VAZ-21124 jerks during acceleration. On the face of it, it doesn't seem like a very ordinary question. But in fact, such twitching becomes not funny at all. You start to feel especially creepy when the VAZ-21124 jerks during acceleration and the check light comes on. Trouble has become reality.

It has long been known that any breakdown is easier to prevent than to fix. Therefore, try to pay more attention to your vehicle while driving. And here a problem arises: not every driver can feel the car and determine the cause in time.

You should immediately decide on the sequence of actions:

1. Checking the car for twitching while idling is unacceptable. This should only be done when moving.
2. The check should begin on the smoothest and least dangerous section of the route, where there is no heavy traffic.
3. To check, start shifting gears one by one by pressing the gas pedal on each gear.
4. If the vehicle begins to jerk without your participation, therefore, the root cause of the problem must be sought in this problem.

Jerks on the gas

There are often situations when the car jerks when driving on gas, but everything is fine on gasoline. The cause may be problematic spark plugs or high-voltage wires.

But why then does the malfunction appear only on gas fuel?

The bottom line is that when using gas fuel, the breakdown requirements are higher than in the case of gasoline. It turns out that the spark follows the path of least resistance and, accordingly, not in the place where it is needed.

As a rule, this happens when the gas pedal is sharply depressed, when the mixture is lean for some period and it is during this period that the breakdown energy increases.

To confirm or refute the version, you can remove the spark plug and look at the condition of the white dielectric.

Sometimes the symptoms are visible directly on it, but there are situations when the breakdown occurs internally. In this case, the check is carried out only at the stand.

It happens like this:

1. Breakdown.
2. The spark plug does not “receive” a spark or the latter is very weak (we write in easy-to-understand language).
3. The fuel-air mixture does not ignite and the cylinder is excluded from the engine operation.
4. The power drops cyclically and the car starts to jerk.

After eliminating the malfunction in the ignition system, the jerking when operating on gas should go away.

Some car owners complain that after replacing all the ignition elements, nothing changes. But at the same time, they ignore the requirements of engine manufacturers about the permissible type of installed spark plug.

In some cases, reducing the spark plug gap may help.

There are also situations when gas and gasoline enter the same injector due to an error by the adjusters.

Diagnostics and repair

Many motorists, unable to determine the cause on their own, turn to a car service for diagnostics. On the one hand, checking systems for operability should be done at a service station, and trusted to professionals, on the other hand, the price is too expensive, it goes to extremes. Therefore, we will consider options for solving the problem with your own hands in the garage.

Before we begin, it's worth understanding why this happens.

Fuel system

Dismantled fuel rail with injectors

The first place to look for a fault in the fuel system is the injectors. It is their clogging that can cause the fuel mixture to be lean or rich, and therefore to solve the problem it is necessary to dismantle this element along with the fuel rail.

The injectors are checked and cleaned on a special stand. If this is not possible, then they are replaced with new ones. Also, it is worth diagnosing the fuel rail for breakdowns. The point is that if air leaks through it, this can cause the car to jerk.

The last option to resolve the issue is that incorrect operation of the fuel pump and lack of pressure in the fuel lines leads to the fact that the gasoline mixture is lean and the car begins to twitch at low speeds.

Throttle valve

Throttle valve before and after cleaning

Here, the main problem may lie in the throttle position sensor. So, if this element malfunctions, the electronic engine control unit receives a command to change the throttle position too late, when the car is already jerking. A sharp change in the amount of forced air, as well as a rich fuel mixture, become the causes of twitching.

Crankshaft sensor

Crankshaft sensor removed from engine

The crankshaft sensor can also cause the car to jerk. This effect was more common on the first models 2110-2112. Of course, in the second and subsequent generations this problem was eliminated.

The sensor gives the ECU contact information about the crankshaft speed, but if it breaks down, the data gets stuck in the last information provided. If you drop the speed from high to low, it turns out that the information has not reached the “brains”, but a lot of fuel is still supplied. Replacing the sensor solves this problem.

Program for eliminating ECU errors

Of course, where would breakdowns be without an electronic engine control unit? Thus, accumulated errors can cause many troubles. Experienced auto electricians call this effect a “glitch.” This is when the firmware can crash due to a critical accumulation of errors. Of course, as a result of this, many malfunctions can occur, but engine jerking is one of them.

Vibration and jerking when reversing

There are situations when the car jerks while moving in reverse, and vibrations are also possible.

Here you need to consider which gearbox is installed.

If your car has an automatic transmission, you need to pay attention to the position of the engine protector.

It is possible that this element of the car was installed incorrectly when filling oil or performing other work. In this case, the exhaust pipe is close to the protection.

When you engage reverse, the engine tilts slightly, which causes vibration.

It is also necessary to pay attention that there are no touches along the entire perimeter.

If necessary, thick rubber seals must be installed.

There are also other possible reasons that are relevant for all cars:

1. Nedogazovka. It is necessary to take into account that the reverse speed is higher than the first, therefore, at low speeds (about 800-1200 rpm), twitching may appear, and the car itself does not have enough strength to accelerate. Almost the same principle applies here as with the second speed.
2. Poor contact. When moving backwards, the engine tilts a little. If there is a poor connection in the wiring, the situation gets worse when the reverse gear is engaged.
3. Suspension. Even in ideal condition, this component gives a certain vibration.
4. Severe wear on the differential.
5. Low-quality CV joints or “shifters”.
6. A worn clutch or some kind of defect if we are talking about a new car. More precisely, the basket presses the disc unevenly onto the flywheel.
7. Wedging in the basket.
8. Problems in the gearbox, namely the reverse gear.

Much depends on the car model. To determine a more precise cause, it may be necessary to check each of the presented versions. But it is better to contact experienced service station employees.

Automatic transmission

The situation when a problem with jerking occurs on an automatic transmission deserves special attention.

In this case, the following reasons are possible.

Control block

ECU malfunction is one of the causes of shocks when switching automatic transmissions.

Depending on the make/model of the car, the electronic unit can be independent or built into the “brains” of the engine.

To solve the problem, the ECU may need to be replaced.

Motor sensor

The cause of jerking when driving a car with an automatic transmission may be a malfunction of one of the control bodies, for example, or the mass air flow (MAF).

In such cases, the engine error may not light up. For example, on Ford Mondeo cars with a 6-speed automatic transmission, the problem may arise due to a breakdown that affects the change in torque.

Solenoids

Failure of these elements in the valve body often leads to jerking of the machine. In this case, the culprit is often the valve responsible for oil pressure.

Most often, it needs to be replaced to solve the problem. This situation is typical for automatic transmissions of the DP series (France).

Automatic transmission wiring harness

Wear or damage to this component causes many problems.

That is why during a major overhaul this unit is replaced first.

Mechatronics board

Some automatic transmissions have a separate unit that controls the solenoids. It is mounted in a tray, and if it breaks, it leads to many problems with the automatic transmission.

A similar component can be found in the Mercedes-Benz 722.9 with a seven-speed automatic transmission or in the six-speed “box” of the GM 6T30 and 6T40.

Hydraulic block

A decrease in oil pressure in the automatic transmission hydraulic system leads to jerking and may occur due to failure of the valve body.

The reason may be normal aging or bending of device elements due to overheating.

Problems with hardware

The worst thing is if the malfunction is caused by mechanical malfunctions of the transmission elements. In this case, disassembly and repair may be required.

For example, in Audi cars with a six-speed automatic transmission, the drum bushings often wear out.

As a result, oil is supplied to the friction pack, and due to lubricant leakage, slipping occurs, and the discs literally “burn”.

Other reasons:

1. Reduced oil level. It is enough to reduce the volume of lubricant by only 500 ml for twitching to appear.
2. Problems with automatic transmission and engine mounts. If there is excessive wear, the engine tilts, which causes jerking.
3. Overheat. The problem may arise when operating vehicles in hot weather when the radiators are dirty and the thermostat is faulty.

This list can be supplemented with a problem with the housing and wear of the band brake rod attachment point.

As a result, an oil leak appears and there is a decrease in pressure in the system, followed by a shock.

Mazda 6 owners faced a similar problem.

Automatic transmission Mazda 6

If difficulties arise in the operation of the automatic transmission, it is important not to delay repairs, but to immediately go to a service station for inspection.

If the cause of the car jerking in motion is mechanical problems, you will have to remove and disassemble the “box”.

But most often it does not come to this, and the issue can be resolved by restoring the electrical part.

Why does the VAZ Ten move jerkily?

Applied to a car jerk

- this is a short-term spontaneous change in the engine crankshaft speed, regardless of the position of the accelerator (“gas”) pedal. In everyday use, as a rule, there are a series of jerks. The extreme case of a jerk is a failure - a noticeable delay in the engine's response to pressing the accelerator pedal.

Conventionally, three types of jerks can be distinguished:

- at the moment of starting movement;

— with steady motion, i.e. with the accelerator pedal in constant position.

To determine the causes of jerking when moving

A car with an injection engine requires special diagnostic equipment, so in this case we recommend contacting a service specializing in the repair of fuel injection systems. However, as practice shows, in most cases jerking is caused by insufficient fuel pressure in the fuel rail, malfunction of the throttle position sensor or mass air flow sensor.

If you have some skills, you can determine the cause of jerking yourself.

A jerk at the start of movement.

At the moment the movement begins, the limiting case of a jerk—failure—most often occurs. The most unpleasant sensations are associated precisely with the delay in the engine’s response to pressing the gas pedal. Sometimes the engine even stalls. A jerk occurs at the moment the throttle valve begins to open, when, based on a signal from the throttle position sensor, the ECU determines the moment of transition from idle mode to load mode and must increase the amount of fuel supplied through the injectors. If the pressure in the fuel line is insufficient (even if the injection duration is increased), there is not enough fuel for a smooth start. It is necessary to check the fuel pressure in the rail or the fuel pump itself.

The cause of jerks during acceleration may be, as in the previous case (“Jerk at the moment of starting movement”), insufficient fuel pressure in the fuel line. The electronic engine control unit, having received a signal from the throttle position sensor about the intensive opening of the throttle at a large angle, strives to maximize the fuel supply, but due to the reduced fuel pressure it is not able to do this. The reasons for this phenomenon and the method of verification are the same as in the previous case.

Jerks during steady motion.

Such jerking is most often caused by a malfunction of the ignition system. Diagnosis and repair are required. Along the way, you can try the following on your own:

— carefully inspect the engine compartment. Turn off the ignition and check the secure fastening and seating of all wires (including high-voltage) and connectors of the ignition module. Start the engine and listen to its operation: the crackling sound when the high voltage breaks down to ground is weak, but distinct. In complete darkness, the spark during breakdown is clearly visible.

-replace spark plugs regardless of their condition and mileage

Pay attention to the condition of the spark plugs: if it is “abnormal”, the engine or its systems may need to be repaired

A specific cause of jerking during steady motion of a car with an injection engine may be a failure of the throttle position sensor. Additional symptoms confirming the malfunction of this sensor are:

- uneven operation of the engine at idle.

-reduction of maximum engine power.

The sensor is non-separable and therefore cannot be repaired. If a sensor malfunction is detected, it is replaced as an assembly.

Your reviews, comments, questions and answers on LADA-10.ru

Everyone can participate in the discussion about the causes of the malfunction and other problems. If you know what to answer, write and thereby help other VAZ 2110 owners in searching for the truth.

Comments on the LADA-10.ru website were launched on January 11, 2012

Hello everybody. car VAZ 2112 8kl. moves jerkily. The failures are minor, but very unpleasant. What was done: 1. Replaced spark plugs and wires2. I connected to one hundred using a scanmaster (I think so). All tests are good. all sensors are working. characteristics are normal.3. cleaned the injectors4. checked the pressure in the fuel rail.5. checked the compression.

I don’t know where else to dig. Help. thank you in advance!

We also have Lada

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Checking VAZ-2107 carburetor

Now let's take a closer look at how to identify the cause of such a malfunction on different car models.

The first will be the carburetor VAZ-2107; there are plenty of cases when the car suddenly starts to jerk while driving.

As already mentioned, you need to start checking with the fuel system:

• First you need to inspect all pipes of the system for cracks;
• Open the tank. It happens that in the summer the lid fits very tightly to the neck, blocking the access of air to the tank. When moving, the pump works and creates a vacuum in the tank, due to which the same pump is then unable to “pull” fuel. It seems like a small thing, but this also happens;
• Inspect the fuel filter located in the pipes leading to the fuel pump. These filters are transparent and easy to visually evaluate;
• You can also check the fuel pump without removing it. It is necessary to disconnect the pipeline coming from the pump from the carburetor and lower its end into some container. Then manually pump the pump into action and evaluate how it pumps fuel - it should supply it in even portions;

• While the fuel pipe is disconnected from the carburetor, unscrew the fitting on which the fuel line fits and remove the small mesh filter, clean it and reinstall it;
• Next comes the carburetor. It is advisable to remove it from the car, rinse it thoroughly, and inspect the accelerator pump membrane.

If actions with the fuel system did not help, we proceed to checking the ignition system.

• We unscrew the spark plugs, check their functionality, and replace them if necessary;
• We check the system wiring for breakdown. This can be done this way - in the dark or in a closed garage (the main thing is that it is dark), open the hood and start the engine. If there are voltage losses on the wiring, they will be immediately noticeable by the sparks that form. Next, we replace the wiring that “breaks through” and check the wire connections;

• Next, we check the distributor, there should be no signs of critical wear, it should be dry under the cover. Be sure to inspect the centrifugal regulator, and also check the vacuum regulator. You should check whether there is a vacuum in the pipe leading to it.
• Then the Hall sensor, coil and switch will be checked for functionality. You can do this yourself if you have the necessary equipment at hand, but you need to know how to check them. But you can contact an auto electrician.
• It is also important not to forget to check that the ignition is installed correctly.

This is in general and all the features of identifying the cause of uneven running on the VAZ-2107.

Checking VAZ-2110

Let's move on to a more modern car - the injection VAZ-2110, which can also twitch when driving.

It’s also worth starting the check with the power system, but it is carried out somewhat differently than on the “Seven”:

• Start with the fuel filter and pump. The filter there is non-separable and diagnostics are done by checking the performance of the pump. It is impossible to carry out the work at home; it is better to contact a service station. There, a special device is connected to the outlet of the fuel filter to measure the outlet pressure. If the pressure does not correspond to the norm, then another measurement is taken, but the device is connected to the fuel pump before entering the filter. This way it is determined whether the insufficient fuel supply is due to the filter or the pump;
• Then the functionality of the injectors is checked. If everything is in order with the specified elements, then the check of the electronic component begins;
• First, all sensors are checked for serviceability and functionality; if they are serviceable, then all that remains is to check the control unit;
• The control unit can often cause jerking if its firmware is broken, that is, it does not operate in the mode it should.

  
  Usually such a malfunction is “cured” by “reflashing”, but if there is internal damage in it, then it is replaced.

As for checking the ignition system, it is in many ways similar to checking the VAZ-2107 system.

It all starts with the spark plugs, then the wiring is checked, then all the components, but taking into account the fact that this system is controlled by an electronic unit that controls the operation of the engine using sensors.

So, when checking the ignition, you will also have to check the performance of the sensors and the unit itself.

VAZ 2114 injector

Owners of VAZ 2114 cars with an injector often complain about the appearance of car jerking and loss of traction. The first thing you need to do is connect to the diagnostic connector and look for errors.

The most common problems that may occur are:

• P0327 - knock sensor, low voltage;
• P1602 - unstable voltage;
• P2127 - gas pedal position sensor, low voltage;
• P2138 - gas pedal position sensor, signal mismatch.

In this case, you need to look at what error Check appears. Most often this is P2127, so this is what you need to pay attention to.

After connecting, you need to look at the information that the sensors provide when you press the gas.

If after pressing the accelerator the indicators change significantly, this may indicate a violation of the resistive layer.

The following steps may be required to resolve the issue:

1. Take off the gas pedal.
2. Loosen the mounting screws.
3. Remove the cover.
4. Wipe the circuit with an alcohol solution.
5. Reassemble the pedal and put it in place. Don't change your position.
6. Take measurements using a potentiometer.

If the data is static, and after releasing the gas the voltage parameters do not change, this indicates a solution to the problem.

Also look at the knock signal for different cylinders. If any of them has a low parameter, this may indicate a problem with the sensor and the need to replace it.

Lada Kalina, VAZ 21099

When operating the Lada Kalina, jerking may occur when driving. They can occur when starting off, during acceleration, or during normal driving.

In most cases, to identify the cause, you need to diagnose the ECU at a service station, but there are situations when you can solve the problem yourself.

Below we will consider possible solutions for different situations that can be applied to other cars, for example, VAZ 21099 injector.

When starting to move

The reason is the slow response of the engine to pressing the accelerator. A jerk appears at the moment the throttle opens, when the sensor of this unit transmits information to the ECU.

Next, the electronic unit determines the moment of transition from the idle mode to the load and makes a decision to add fuel.

When there is a shortage of pressure in the fuel supply system, jerking occurs.

During acceleration

Here the reason is the same as in the case discussed above. When you press the gas, due to lack of pressure, less fuel is supplied to the engine than necessary.

While driving

Such problems are often caused by breakdowns in the ignition system. To check the version, do the following:

• open the hood;
• turn off the ignition;
• check the quality of the wires;
• start the engine and listen to it for the presence of a crackling sound/breakdown;
• change the spark plugs and inspect their condition, and if problems are identified, make repairs.

The cause of jerking when driving the Lada Kalina may be a breakdown of the sensor that displays information on the throttle valve.

The problem can be identified by uneven operation of the motor and a decrease in its power. The only way out in this case is to replace the faulty element.

While driving

It is also an unpleasant situation when the car has jerks and dips during acceleration. This can happen both when driving and when starting off. A particularly unpleasant, or even dangerous, situation can arise while driving, for example, when a car is about to overtake, and then there is a sudden failure.

The causes of jerks during acceleration can be both those already mentioned and slightly different ones:

• If you have a carbureted car that jerks when accelerating, this may indicate that the ignition is too early. You need to set the lead angle. And checking the ignition timing is quite simple: at speed 4, accelerate to 50 km/h and brake sharply. If detonation lasts 1-2 seconds, then the ignition is set perfectly, the reason is not there;
• on “injectors” everything is controlled electronically. There, the jerking while driving and during acceleration may be due to the mixture being too lean. But this should be shown by diagnostics in the service. If the sensors “know about this, but are silent,” then it is quite possible that they themselves are faulty and must be replaced.

Opel Astra

A common problem is the appearance of jerking while driving an Opel Astra. In this case, the malfunction most often appears after the engine has warmed up to 50 degrees Celsius.

The first thing to do is to carry out diagnostics and count errors. During the assessment process, it is necessary to look at the injection timing and EGR sensor/valve performance.

After that do the following:

1. Warm up the engine to operating voltage.
2. Check the voltage at the EGR contacts (there are five in total). To solve this problem you need to use needles. There should be about 14 V on the outermost contacts, about 5 V on the second one from the windshield, and on the third one there should be from 0.65 to 2.0 V.

3. Check the wires that go to the EGR.
4. Make sure the valve is intact. Perhaps it has malfunctioned.
5. If the valve and wires are intact, only the ECU remains. It is necessary to open the block and see what problems there are.

Checking Ford Focus

The last car will be the Ford Focus 3 injector, which is not surprising, but it can also twitch when driving.

Note that the sequence of checking the ignition and power systems on this car has the same algorithm as on the VAZ-2110. But let’s assume that our car is equipped with an automatic transmission, and no problems were found in the engine systems.

As for checking the automatic transmission, you can only check the oil level yourself, but you need to know how to do it correctly.

A more in-depth check can only be done on the service. There, using special stands, they will first check the performance of the engine, and then diagnose the operation of the automatic transmission.

Also read about the reasons why.