Engine Troubleshoot

Smooth It Out: Understanding and Resolving Car Jerking During Acceleration

Car jerks when accelerating

The most common causes of car jerking when accelerating include a dirty air filter, faulty MAF sensor, clogged catalytic converter, bad spark plugs, and transmission problems. In some cases, the problem may be due to moisture buildup in the engine, which can cause misfires and jerking at low speeds.

In this article, we’ll explain the possible causes of this common issue, and what you can do to fix it.

What Causes A Car To Jerk When Accelerating?

When your car jerks while accelerating, it can be caused by problems with engine sensors, dirty filters, problems with the fuel and ignition systems, or problems with the transmission.

One of the most common symptoms of a car jerking when accelerating is a noticeable and uncomfortable jerking sensation. This can happen when you press down on the accelerator pedal, and your car fails to accelerate smoothly. Instead, you will feel a sudden jolt or jerk

Here are some possible causes in more detail:

Cause 1. Faulty Spark Plugs

Bad spark plugs are one of the most common reasons why a car will jerk when accelerating. The spark plugs are responsible for igniting the air-fuel mixture in the engine’s combustion chamber.

If the spark plugs are worn, damaged, or fouled, they may not be able to generate a strong enough spark to ignite the air-fuel mixture properly, which can cause jerking or hesitation during acceleration.

A bad spark plug
A badly worn spark plug

When the engine is not firing on all cylinders, it can cause incomplete combustion, which can result in a buildup of carbon deposits on the spark plugs, valves, and other components of the engine. This can cause the engine to misfire, run poorly, or even stall.

Cause 2. Clogged Fuel Filter

The fuel filter is responsible for removing dirt, debris, and other contaminants from the fuel before it enters the engine. If the fuel filter is clogged, it can restrict the flow of fuel to the engine, which can affect the air-to-fuel ratio and cause jerking or hesitation during acceleration.

blocked fuel filter
A dirty fuel filter can cause low fuel pressure and engine stalls

When the engine is not receiving enough fuel, it can cause incomplete combustion, which can result in a buildup of carbon deposits on the spark plugs, valves, and other components of the engine. This can cause the engine to misfire, run poorly, or even stall.

Cause 3. Dirty Air Filter

A dirty air filter can also cause a car to jerk when accelerating. The air filter is responsible for preventing dirt, debris, and other contaminants from entering the engine.

If the air filter is dirty or clogged, it can restrict the amount of air that enters the engine, which can affect the air-to-fuel ratio and cause jerking or hesitation during acceleration.

A dirty air filter will restrict the amount of air your engine can use

When the engine is not receiving enough air, it can cause incomplete combustion, which can result in a buildup of carbon deposits on the spark plugs, valves, and other components of the engine. This can cause the engine to misfire, run poorly, or even stall.

A dirty air filter can also cause reduced power, decreased fuel economy, and rough idling.

Cause 4. Faulty Mass Airflow Sensor

A very common reason for a car to jerk when accelerating is a bad MAF (mass airflow) sensor.

The MAF sensor is responsible for measuring the amount of air entering the engine and sending this information to the engine control unit (ECU). The ECU uses this information to adjust the fuel injection and ignition timing to ensure optimal performance and efficiency.

If the MAF sensor is malfunctioning or sending inaccurate readings to the ECU, it can cause the engine to receive too little or too much fuel, which can result in jerking or hesitation when accelerating. This is because the air-fuel mixture is not properly balanced, resulting in incomplete combustion and poor engine performance.

In addition to jerking during acceleration, a bad MAF sensor can also cause rough idling, stalling, or a decrease in fuel economy.

Cause 5. Damaged Acceleration Cable

A damaged accelerator cable can cause a car to jerk when accelerating on older vehicles that do not have drive by wire accelerators installed.

The accelerator cable is responsible for transmitting the movement of the accelerator pedal to the throttle body on the engine. If the cable is damaged or worn, it can cause the throttle to open inconsistently or not at all, which can result in jerking or hesitation when accelerating.

In addition, a damaged accelerator cable can also cause the engine to idle poorly or stall, as it can affect the amount of air and fuel that is delivered to the engine.

A visual inspection of the accelerator cable can usually indicate if it is damaged or worn, and if it is then it will need to be replaced to ensure smooth and consistent acceleration.

Cause 6. Damaged Acceleration Cable

A worn transmission is another common reason for a car to jerk when accelerating. A transmission that is worn or damaged can cause a variety of symptoms, including jerking or slipping when accelerating. This is because the transmission is responsible for transferring power from the engine to the wheels, and any issues with the transmission can affect the smoothness of this process.

One common issue with a worn transmission is slipping, which occurs when the transmission fails to engage properly and the engine revs up without a corresponding increase in speed. This can cause the car to jerk or lurch forward when accelerating. In addition, a worn transmission can also cause rough shifting, delayed shifting, or a complete loss of power.

Cause 7. Low Fuel Pressure

The fuel system is responsible for storing and delivering fuel to the engine. If there is an issue with the fuel system that causes low fuel pressure it can cause jerking while accelerating.

Some causes of low fuel pressure include:

  1. Faulty Fuel Pump: The fuel pump is responsible for delivering fuel from the gas tank to the engine. If the fuel pump is malfunctioning, it may not be able to deliver fuel at the correct pressure, causing low fuel pressure.
  2. Malfunctioning Fuel Pressure Regulator: The fuel pressure regulator is responsible for maintaining a consistent fuel pressure in the fuel system. If the fuel pressure regulator is malfunctioning, it may not be able to regulate the fuel pressure correctly, causing low fuel pressure.
  3. Leaking Fuel Injector: A leaking fuel injector can cause fuel to leak out of the fuel system, reducing the fuel pressure.
  4. Clogged Fuel Line: A clogged fuel line can restrict the flow of fuel to the engine, causing low fuel pressure.
  5. Bad Fuel Pressure Sensor: The fuel pressure sensor is responsible for sending information about the fuel pressure to the engine control unit. If the sensor is malfunctioning, it may not be able to send accurate information, causing low fuel pressure.

What Next – How To Fix A Car That Jerks When Accelerating

Start by carrying out an ECU diagnostic test using a suitable OBD-II tool to read the car’s computer system and identify any engine error codes. This test can help identify issues with sensors, fuel injectors, and other components.

Next, carry out a road test to identify any issues while accelerating. During the test, pay attention to the following: when exactly does the car jerk or hesitate while accelerating, does the engine make any unusual noises and are there any warning lights on the dashboard?

If there are engine error codes present, then use them to decide what engine components need testing or replacing.

Here are some other steps that you can take to try and figure out whats going on.

1. Spark Plug Replacement

One of the most common causes of car jerking during acceleration is a faulty spark plug. If you suspect that your spark plugs are the culprit, you should replace them as soon as possible. This is a relatively simple and inexpensive repair that can be done at home with a few basic tools.

2. Fuel Filter Replacement

If the fuel filter in your car becomes clogged or dirty, it can restrict the flow of fuel to the engine, which can cause jerking or hesitation during acceleration. If you suspect that your fuel filter is the problem, you should have it replaced. This is another relatively simple and inexpensive repair that can be done at home or by a professional mechanic.

3. Air Filter Replacement

The air filter in your car is responsible for filtering out dirt and debris from the air that enters the engine. If the air filter becomes clogged or dirty, it can restrict the flow of air to the engine, which can cause jerking or hesitation during acceleration.

4. Mass Airflow Sensor Replacement

The mass airflow sensor in your car is responsible for measuring the amount of air that enters the engine. If the mass airflow sensor becomes dirty or faulty, it can cause the engine to receive incorrect readings, which can result in jerking or hesitation during acceleration. If you suspect that your mass airflow sensor is the problem, you should have it replaced. This is a more complex repair that should be done by a professional mechanic.

5. Transmission Repair or Replacement

If your car’s transmission is the cause of the jerking or hesitation during acceleration, you may need to have it repaired or replaced. The cost of transmission repair or replacement can vary depending on the extent of the damage and the make and model of your car.

6. Fuel System Repair

This can include repairs to the fuel pump, fuel injectors, or fuel lines. This is a more complex repair that should be done by a professional mechanic. The cost of fuel system repair can vary depending on the extent of the damage and the make and model of your car.

About the author

The Motor Guy

The Motor Guy is a passionate car enthusiast with a love for troubleshooting and diagnosing all sorts of vehicle problems.

With years of experience in OBD diagnostics, he has become an expert in identifying and solving complex automotive issues.

Through TheMotorGuy.com, he shares his knowledge and expertise with others, providing valuable insights and tips on how to keep your vehicle running smoothly.

Qualifications:
- 12 years experience in the automotive industry
- ASE Master Automobile Technician
- A Series: Automobile and Light Truck Certification, A9 Light Vehicle Diesel Engine Certification
- Bachelor's Degree in Information Systems

2 Comments

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  • I’ve been experiencing car jerking when accelerating and suspect it might be the MAF sensor as my car has rough idling too. How can I test the MAF sensor to determine if it is indeed faulty?

  • I recently noticed my car jerking when I accelerate and sometimes there’s a delay in acceleration followed by a sudden jerk. Could this be related to the acceleration cable, and if so, how can I confirm this is the issue?