A smooth and comfortable ride is what every driver aspires to achieve when driving.
Sometimes not everything goes as planned and the car starts to jerk when accelerating.
This problem has many potential causes that may be hard to pinpoint. For example, the issue may 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 a simple guide on how to identify the reason for the jerking acceleration.
Table of ContentsShow
Why Does My Car Jerk When Accelerating?
An internal combustion engine consists of many moving parts that all must run smoothly and synchronized to offer a comfortable driving experience.
If the car runs smoothly when idling but jerks when accelerating it implies a problem related to the combustion chamber.
In most cases, this means that the engine does not get enough fuel or air but may also be due to the combustion of the mixture.
This means that the cause of this problem is often due to either 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 have determined what systems are usually causing an unsmooth, jerky acceleration.
Unfortunately, many of these causes are hard to differentiate and we have therefore made a more comprehensive list so you can more easily identify the culprit.
Bad Spark Plugs
Spark plugs ignite the air and fuel mixture in the combustion chamber at exactly the right moment, that is when it works properly.
A bad spark plug may either ignite the air-fuel mixture prematurely, late, or not at all.
When this happens, the cylinder will misfire which will make the car jerk if the problem is severe enough.
Many times, when the spark plugs are bad, more signs may be seen such as a check engine light, higher fuel consumption, rough idle, and more.
The price of spark plugs differs, a pack of premium spark plugs will cost about $50 while typical spark plugs cost much less.
Clogged Catalytic Converter
The catalytic converter receives all the gases formed in the internal combustion chamber.
In there, the gases get converted to less toxic gases which is much kinder to the environment.
Unfortunately, catalytic converters can give up and when they do, they are usually clogged. This means that the exhaust cannot pass outside, compromising the pressure in the engine.
In most cases, a catalytic converter is second to a primary problem. Bad spark plugs, contaminated fuel, or oil in the catalytic converter are just a few causes of a bad catalytic converter.
It is therefore important to exclude a primary cause before replacing a catalytic converter.
Other symptoms of a bad catalytic converter include bad fuel efficiency, check engine light, and difficulties starting the car.
Blocked Air Intake
The air is just as important as the fuel, without each other, no combustion nor power would be generated.
The engine must have clean air to function properly. Debris, insects, dust, and other particles are filtered out to provide a balanced air-to-fuel ratio.
The filter does not clean itself and must therefore be changed regularly. If not, it may be clogged which will effectively choke the engine.
If you do not remember the last time you changed your air filter, it may be a good idea to check it out.
Other symptoms that may occur when the air filter is clogged include illuminated check engine light, reduced power, and engine misfires.
As time goes by more and more sensors get added to cars and other vehicles.
If a sensor stops working or emit wrong values to the ECU, it can cause problems with many multiple systems in the car.
When it comes to jerky acceleration, two sensors should have a special mention – Mass Airflow Sensor (MAF) and the Fuel Pressure Sensor.
Both these sensors affect the fuel/air mixture, which may cause acceleration problems, including jerky acceleration.
These sensors also may cause similar problems such as stalling, difficulty starting, low power, and bad fuel economy.
Fuel Pump, Filter, And Injectors
A common denominator with jerky accelerations is an ineffective air-fuel ratio. Many things affect the fuel component of the mixture, including the fuel injectors, filter, and pump.
Because all these components will 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 potential culprits and generally comes down to an inappropriate air/fuel mixture in the combustion chamber.
In most cases, it comes down to faulty spark plugs, the catalytic converter, sensors, and other reasons mentioned in this article.
It may be difficult to differentiate between the causes as the symptoms and signs overlap substantially.
The best way to distinguish the causes is to do an OBD scan. If you do not have an OBD scanner nearby, you may try to remember when the last time was you changed your fuel filter, air filter, etc.
Keep in mind that a catalytic converter should last the whole lifetime of the car. If it turns out that the catalytic converter is bad, there is usually another primary cause that should be investigated.
Whatever the cause may be, make sure to fix the problem as soon as possible to prevent any damage to the engine and its components.