A smooth and comfortable ride is what every driver hopes for when they set out in their car.
Unfortunately, things don’t always go as planned and the car starts to jerk when accelerating.
This problem has many potential causes, so it can be hard to pinpoint the specific reason. For example, the issue could be related to spark plugs, the catalytic converter, air intake, and more.
To make things easier for you, we have listed the most common causes and created a simple guide on how to identify the reason for the jerk when accelerating.
Let’s jump right into the guide!
Table of ContentsShow
Why Does My Car Jerk When Accelerating?
An internal combustion engine contains many moving parts that all must run smoothly and be synchronized to provide a comfortable driving experience.
If your car runs smoothly when idling but jerks when accelerating, it suggests a problem related to the combustion chamber.
In most cases, this means the engine does not receive enough fuel or air but it could also be due to improper combustion of the mixture.
This means the cause of this problem is often one of the following:
- Bad spark plugs
- Clogged catalytic converter
- Blocked air intake
- Faulty sensors
- Fuel pump, filter, and injector
Causes Of Rough Acceleration
Now we know which systems are usually responsible for an unsmooth, jerky acceleration.
Unfortunately, some of these causes are hard to differentiate. To help, we have created a more comprehensive list to help you determine the culprit.
Bad Spark Plugs
Spark plugs ignite the air and fuel mixture in the combustion chamber at precisely the right moment. At least they do when they work properly.
A faulty spark plug could ignite the air-fuel mixture prematurely, late, or not at all.
When this happens, the cylinder will misfire which can make the car jerk if the problem is severe enough.
In many cases, when the spark plugs are bad, other symptoms are apparent such as a check engine light, higher fuel consumption, rough idle, and more.
The price of spark plugs varies. A pack of premium spark plugs will cost about $50 while standard spark plugs cost far less.
Clogged Catalytic Converter
The catalytic converter receives all the gases formed in the internal combustion chamber.
Once inside, the gases are converted to less toxic gases that are much kinder to the environment.
Unfortunately, catalytic converters can stop working and, when they do, they are usually clogged. This means the exhaust cannot function properly, compromising the pressure in the engine.
In most cases, a catalytic converter fault is caused by another problem elsewhere. Bad spark plugs, contaminated fuel, or oil in the converter itself are just a few possible causes of a bad catalytic converter.
This is why it is important to check for any other causes before replacing a catalytic converter.
Other symptoms of a faulty catalytic converter include bad fuel efficiency, the check engine light, and difficulty when starting the car.
Blocked Air Intake
The air is just as important as the fuel. Without both, no combustion would be achieved, thus no power would be generated.
The engine requires clean air to function properly. Debris, insects, dust, and other particles are filtered out to ensure a balanced air-to-fuel ratio.
The filter does not clean itself and must therefore be changed regularly. If it isn’t, it may become clogged which will effectively strangle the engine.
If you can’t remember the last time you changed your air filter, it is probably a good idea to check it out.
Other symptoms that can appear when the air filter is clogged include an illuminated check engine light, reduced power, and engine misfires.
As time passes, more and more sensors are added to cars and other vehicles.
If a sensor stops working or provides inaccurate readings to the ECU, it can cause problems with multiple systems in the car.
When it comes to jerky acceleration, two sensors need a special mention: the Mass Airflow Sensor (MAF) and the Fuel Pressure Sensor.
Both these sensors affect the fuel/air mixture, which may lead to acceleration problems, including jerky acceleration.
These sensors can also cause similar problems such as stalling, difficulty starting, low power, and reduced fuel economy.
Fuel Pump, Filter, And Injectors
A common cause of jerky acceleration is an ineffective air-fuel ratio. Many things can affect the fuel component of the mixture, including the fuel injectors, filter, and pump.
Because all these components can compromise the fuel/air mixture, the symptoms overlap substantially and include poor idle, loss of power, and an illuminated check engine light.
Jerky acceleration is a symptom that has many possible causes that are generally the result of an inappropriate air/fuel mixture in the combustion chamber.
In most cases, the root cause is faulty spark plugs, the catalytic converter, sensors, or other reasons mentioned in this article.
It can be difficult to differentiate between the causes as the symptoms overlap significantly.
The best way to distinguish the causes is to conduct an OBD scan. If you do not have an OBD scanner available, try to remember when you last changed your fuel filter, air filter, etc.
Keep in mind that a catalytic converter should last the entire lifespan of the car. If it turns out that the catalytic converter is faulty, there is usually another issue that should be investigated.
Whatever the cause is, make sure to fix the problem as soon as possible to prevent any damage to the engine and its components.