The car jerks when accelerating: why and what to do?

Self-check of the car, identification of symptoms

To understand the possible cause of the breakdown, you should clearly identify the symptoms, and based on this, draw some conclusions.

When the car is warmed up to operating temperature, when you press the gas pedal, it begins to “stupid” or twitch slightly, and then when you pick up speed, this problem disappears and the car operates normally.

If this problem occurs only during acceleration, and not, for example, when starting from a standstill, then the reasons will be the same. If the car jerks when starting from a standstill, then this may be a problem with the clutch or basket. If vibration is felt while driving and not only during acceleration, this may indicate a failure of the cushions securing the engine.

Additionally, we recommend reading our expert’s article, which talks about what vibration when braking means.

You can learn how to replace a timing belt with your own hands from our specialist’s detailed material.

Conclusion

If the car jerks during acceleration or when driving at low speeds, the reasons may be defects in the fuel system, engine, gearbox, ignition or other components. To understand which systems require repair, you need to pay attention to the nature of the twitching, intensity and accompanying symptoms. To accurately determine the problem, it is advisable to carry out diagnostics in a workshop, especially if the owner does not have experience in repairing the car with his own hands or does not have the necessary tools.

Diagnostics at the service center

Diagnostics can also be done at a service center. Especially if the car is fuel-injected, a special device is needed. It is connected to the control unit and shows where and on which sensor the problem is possible. The same goes for diesel cars. To check diesel engine injectors, you need a special stand. Without it, it is impossible to determine what condition they are in.

Dying fuel pump

Another part that can cause your car to jerk when accelerating is the fuel pump. If it is about to die, it may not be providing the optimal level of pressure to the fuel injection system. This will result in insufficient fuel delivery and jerking.

Causes of jerking during acceleration

There can be several reasons why a car jerks during acceleration.

Malfunctions in the engine ignition system

If the ignition fails, it will be strongly felt during acceleration. This happens because when you press the gas pedal, fuel is injected into the cylinders, and detonation should occur there. If the ignition is set incorrectly or fails, then fuel flows, but the spark strikes at the wrong time. In other words, some part of the fuel does not ignite or ignites at the wrong time. Some cylinders may not detonate at all. This all leads to unbalanced work and, consequently, jerks. The cause could also be faulty spark plugs or armor wires. It is advisable to change spark plugs sometimes. Spark plugs are checked using special equipment, where, at a pressure the same as in the engine, it is checked whether the spark plug produces a spark.

Even when the spark plugs appear to be in good working order and have no defects, this does not mean that they perform excellently. It is recommended to buy candles from a manufacturer that is not the cheapest, since even new ones may not pass the bench test.

Armor wires are checked with an ohmmeter for the presence of the required resistance. You can also check the quality of the connections between the wires and the spark plugs. The procedure should be carried out with a warm engine. You should take water into a bottle and use a sprayer to distribute it with the engine running on the armored wires and the connection with the spark plugs. If the engine speed begins to decrease and the car starts to stall, then the wires should be replaced.

If you do not understand how the ignition is set, it is better to contact a specialist. This process is quite accurate, there are no mistakes to be made there.

Malfunctions in the power system

The most common reason for a car jerking during acceleration is a problem with the power and fuel supply system. When you press the gas pedal due to contaminated elements of the fuel system, there is not enough fuel to accelerate. This is why jerks occur during acceleration.

The problem may be:

1. Filters. The air filter and fuel filter need to be changed regularly. This is a consumable item that quickly breaks down.
2. Contamination of the fuel supply system. In carburetor cars, these are jets in which the slightest dust or pieces of dirt greatly affect the flow of fuel. Injector nozzles may become clogged.
3. Fuel pump. If it fails or partially begins to show less performance, namely, does not have time to pump the required fuel pressure into the system, then during acceleration this deficit will be visible.

There are various aerosols and additives for cleaning fuel systems. If you choose a product from a trusted manufacturer, they work very well. But this may not be enough in all cases. There are cases where mechanical cleaning or repair of individual parts is required. A valve or some other part of the mechanism may fail.

Bad spark plugs and/or coils

Sharp jerks during acceleration can occur when something is wrong with the fuel ignition. A faulty spark plug or failed ignition coil will cause misfire in one of the cylinders. This may cause slight jerking, especially when you are trying to accelerate.

In addition, unstable idling will be additional confirmation of problems with the spark plug or coil.

Resolving identified problems

Once the cause has been identified, you can begin to eliminate it. In most cases, this work should be entrusted to specialists. After all, the reasons that at first glance were key are not always exactly what they are. Correct ignition tuning, carburetor adjustment, injector adjustment is something that is best entrusted to a knowledgeable person. If it was determined that the jerking was caused by dirty filters, then you can use an aerosol cleaner. It is sprayed into the air filter hole. Fuel tank additives also perform quite well. These additives clean the fuel line pipes and all other elements. XADO additives have proven themselves well.

Dirty throttle

Jerking when accelerating can also occur if the throttle valve is dirty. The car will lack power and may stall after you press the gas pedal once and then let it idle. You can use special products from auto stores to clean the throttle body, but be careful. Excessive throttle body cleaning in older vehicles can result in high engine idle speed due to wear on the throttle body. Sometimes minor repairs to this unit may be required.

Mass air flow sensor or crankshaft position sensor

Failure of these sensors can also cause the engine to run rough. Incorrect data on the amount of air entering the engine leads to incorrect opening times of the injectors and, as a result, incorrect preparation of the fuel mixture. The crankshaft position sensor can also cause confusion, due to which the moment of opening the injectors and the formation of a spark in the spark plugs will be chosen incorrectly. Hence the uneven operation of the engine with dips when picking up speed. Diagnostics will help determine the faulty sensor. This sensor will have to be replaced.

The car is shaking, what should I do?

At the first stage, the machine is diagnosed. Let's say that you have a Niva with a carburetor engine in your garage. Your car already shows signs of “illness” at the first stage of movement. Or the car started moving without any hassle, but when a certain number of revolutions was reached, the engine malfunctioned. All this will not give answers, but only creates questions, because anything can break. In any case, if unstable operation of the car’s power unit is noticed while pressing the accelerator pedal, the first thing you should do is:

• Check air and fuel filters. The supply of air and fuel to form a combustible mixture will be difficult if these elements are heavily contaminated.
• Check the fuel pump. Its incorrect operation leads to unstable fuel supply.
• Check fuel pressure. The supply of the fuel-air mixture under insufficient pressure often leads to jerking of the car. The pressure when the engine is running should not exceed 3 kgf/cm2.

Most of the reasons lie in the car's fuel system.

The car jerks while driving - reasons

As a rule, such jerks occur due to a malfunction of the ignition system. However, if a problem occurs on the road, you can try to fix the problem yourself. To do this we do the following:

• Turn off the ignition, lift the hood and make sure that all high-voltage wires are securely attached to the coil and spark plugs.
• Then start the engine and listen to the engine, listen for any extraneous crackling or clicking noises. The point is to check whether there are any “breakdowns to ground”, that is, whether the spark is going somewhere else other than the spark plug. This is best checked in the dark, then you will not only hear a crash, but also see how it hits, for example, on the body or somewhere else.

If the check does not lead to anything, I recommend unscrewing the spark plugs and inspecting them; perhaps there is carbon on the spark plugs or they simply need to be replaced. If you have a set of new spark plugs, check to see if the engine's performance changes or if the jerking goes away after replacing the spark plugs. If the car jerks at speed even after replacing the spark plugs have disappeared, then the problem was in them, but if not, continue searching or try to reach the nearest service center, they will certainly help you solve your problem.

The most common problem that car owners may encounter is sudden “jerking” of the car in different situations. For example, when accelerating, at low speed or at the very beginning of the movement. Those who have been driving for decades do not focus on this at all. This is explained by the fact that these “symptoms” can be expressed in any car, and it doesn’t matter how old it is, what brand it is, or how much experience its driver has.

The Lada Ten, the Hyundai Solaris, and any other car can “rush” off the ground. But this, in any case, is a deviation from the normal operation of the engine. Therefore, at the first unpleasant situations, it is necessary to identify the cause and get rid of the problem. Because the longer you ignore movements of this kind, the more the entire repair will cost you.

A jerking car is not the most desirable road user. If something happens, you will definitely add a couple of accidents to your collection. Photo: desertoasisautorepair.com

By the way, you should not try to solve the problem on your own if you are not confident in your skills and abilities. Entrust your car to a knowledgeable and experienced mechanic at a service station . Do this as soon as possible.

We are looking for the cause in the ignition system

• Broken spark plugs. Spark breakdown through a ceramic insulator, violation of the air gap due to erosion of the electrodes are the most common causes of misfires.
• Malfunction of high-voltage wires. The reason may be a wire break, tip damage, resistor burnout, or insulation breakdown, due to which the charge flows along the path of least resistance to ground, rather than being generated by the spark plug inside the cylinders.

An incompletely dressed tip of high-voltage wires (HVW) also causes a spark to break down to ground. Such situations often arise on cars where access to spark plugs is limited by the intake manifold. With proper skill, on many engines, spark plugs can be changed without removing the manifold, but due to limited access to the IVP tips, jerking occurs at low speed after repair work.

• Broken ignition coil. A high voltage voltage is generated inside the coil. As in the case of GDP, a violation of the housing insulation will lead to spark flow to ground. Other common causes of failure include interturn short circuits, leading to overheating. Failures manifest themselves as an increase in charge accumulation time, a decrease in impulse strength, the absence of damped oscillations and the creation of interference.
• Lost contact in the ignition coil power circuit. It is worth not only checking the supply voltage and ground, but also inspecting the connecting blocks for broken latches and fasteners, and making sure that the wire insulation is intact. Often, with such malfunctions, twitching and stalling of the engine begin to bother the owner in wet weather or after driving over bumps.

Problems with powertrain control calibrations

Very often, a breakdown of any sensor, ignition module, is displayed by a message on the instrument panel. However, there are exceptions when all mechanisms operate normally. There seem to be no malfunctions, but the engine still jerks when reaching speed. In this case, incorrect ECU calibration is to blame.

By the way, such symptoms do not always appear. Most often this happens when the engine is not warmed up enough. I had to observe when a cold engine experienced failures during acceleration. The reason for this behavior was the insufficient supply of fuel to the cylinders.

The way out of the situation is to update the software, which will not contain errors and will work without failures. As for the rest of those involved in acceleration jerks, not counting the injectors that have worn out over time and the faulty module, everything is fixable and does not pose a serious threat. It is important to promptly identify such a problem and eliminate it.

If we talk about turbocharged engines, jerks when the car moves are caused by the turbine itself. The weak point of the part is the pressure adjustment system, namely the electric drive, the electromagnetic valve element. The problem disappears after replacing the valve. Another question is when you have to completely change the turbine.

Poor quality fuel

Poor fuel quality is often the cause of acceleration failures. One of the possible situations that can deteriorate the quality of fuel is the ingress of water into it. If there is water in the fuel, the engine will definitely not work normally. For information: if water gets into aviation fuel, the aircraft engine instantly fails.

Substandard fuel in this area is one of the main causes of accidents in aviation. On earth, this problem costs the car owner less blood. If a car owner has filled the tank with fuel and water, then this fuel must be drained. Otherwise, you will have to change the fuel pump and injectors. If there is no way to drain the fuel, you will have to wait until the fuel is used up.

The appearance of jerking in the car when you sharply press the gas

If the cause is not related to the fuel pump, then these symptoms may indicate the so-called “triple” of the engine. A situation arises in a car in which out of 4 cylinders only one can work correctly. As a result of the “triple”, the engine simply cannot respond in time to pressing the gas pedal, after which similar problems arise. You can deal with the breakdown in the following ways:

• If the oxygen supply sensor is not working properly, the system is diagnosed using a multimeter. If any faults are found, it is simply replaced.
• If the valve timing in the engine is shifted, it is necessary, with the help of car service specialists, to adjust them according to the appropriate instructions.
• Detection of an incorrect glow number of spark plugs is resolved by installing a new set with the correct number.
• The problem of clogged injectors can only be solved at a car service center. To do this, they are installed on a special stand, which simulates the operation of a motor, and washed with a special solvent.
• The problem can also arise if the emulsion tube and well located in the design of the second chamber of the carburetor engine are clogged. The only solution here is to flush the carburetor and pipe with kerosene.

Engine error P0300

Modern ECUs (Engine Control Module) are equipped with a developed self-diagnosis program that allows you to accurately identify many faults. Since in the event of poor combustion of the fuel injection system in the cylinders, unburned fuel escapes into the atmosphere, polluting it, the OBD II standard involves identifying misfires. When a malfunction is detected, the corresponding fault codes are written to the non-volatile memory of the ECU:

• P0300 – multiple misfires. Indicates repeated interruptions in the operation of several/all cylinders;
• P0301 – misfire in the first cylinder;
• P0302 – misfire in the second cylinder;
• P0303 – misfire in the third cylinder;
• P0304 – misfire in the fourth cylinder.

The last digit in the code always indicates the serial number of the cylinder.

If numerous misfires are detected, the ECU is able to turn off the faulty cylinder so as not to ignite gasoline in the exhaust system and damage the catalyst. To exit the emergency mode on many cars, it is enough to restart the engine. On some cars you will have to remove the terminal from the battery for 2-3 minutes.