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May 16 2020

Why Does the Car Jerk While Driving? Here are the Possible Causes


For some strange reason, we have a bad habit of wanting our cars to run smoothly. But it is a mission at least complex unless we have the best of our luck on our side. Suddenly, one day it starts to jerk and we were puzzled. Furthermore, they are not only jerks but sometimes they can also be annoying vibrations while stopped.

Why does he do this? What have we done to the car so that it responds to us like this? Maybe nothing, it was simply bad luck or just wear and tear, although our driving style and driving conditions also help this considerably. So what can we do? It will depend on many factors, since the stumbles can be cold or hot, stopped or moving, at low or medium speed, when changing gears or, simply, with the engine idling.

There can be many causes behind this unpleasant move, including problems in the starting system, fuel supply, engine, or exhaust pipe. You can even notice it using the engine icon in the instrument cluster to warn you of a problem. The jerks, if they are sudden and/or prolonged in time, can be very dangerous and lead not only to damage to the vehicle but also to the possibility of a traffic accident.

"My car jerks and shudders when I accelerate, but it stops when I take my foot off the pedal." What could be the problem? It can be the result of insufficient fuel, air, or sparks supply during the ignition cycle. Worn spark plugs or the wires connected to them are one of the most common causes. A clogged catalytic converter is another reason a car can jerk, as a blockage can interrupt the airflow from the exhaust system.

"When I put first, my car sometimes trembles until I put it at a higher speed." The most likely reason for a car to jerk when accelerating from a standstill is because of a clutch problem. It could be due to a worn friction material or a pressure plate defect (or a combination of both). It could also be caused by an oil leak that could have contaminated that critical junction point.

"My car is very unstable and jerks when I accelerate at low speeds, but nothing happens at higher speeds." In addition to some of the causes mentioned above, moisture in the distributor cap can also cause the vehicle to jerk somewhat when accelerating. Another possibility has to do with the engine mounts. A mount that is loose, worn, or broken will make any car vibrate at low revs.

"My engine is idling at stoplights and junctions, and sometimes it seems like it's going to stop." Along with defective spark plugs, the accumulation of dirt is the most conducive cause of vibrations when stopped. A clogged filter or fuel injection system can deprive your engine of fuel or oxygen. As a car age and accumulates wear and tear, the valves can become blocked with mud. If the vibration only occurs at idle, it could be a small leak in the engine vacuum or a worn electrical component. 

After an overview of the reasons why our car can jerk, it is time to break down the causes that can motivate them.

Blocked Fuel or Airline:

Thermal engines need air and fuel to run. Inside the block, the air mixes with the fuel and the spark plugs/glow plugs create an explosion that moves the pistons. This cycle continues over and over again, allowing the car to move. If there is a blockage in the lines that allow fuel or air to enter inside, the cycle is interrupted and can cause jerks when accelerating. Usually, a warning light will appear in the instrument cluster (the one shaped like a motor) if one of the lines is blocked.

Moisture Accumulation:

If moisture starts to permeate the car's distributor cap, it's all the more reason for annoying rattling when you step on your right foot. This can happen relatively easily when you are parked outside in cold, wet weather. The best way to avoid this phenomenon is to try to park in the hottest and driest place you can find. A thermal cover can also help reduce the risk of condensation when the shelter is not an option and cooler weather is expected.

Clogged Catalytic Converter:

This component is one of those that can surely sound to you for providing the odd headache to the owners of a diesel. The catalytic converter is responsible for regulating the emissions that come out of the exhaust. Sometimes the fuel/air mixtures flowing through it can become clogged, which can cause an unwanted jerk or jog movement when you press the accelerator.

Other symptoms may include a delay in power demand response, increased fuel consumption, and even the smell of rotten egg from hydrogen sulfide. You may be able to mitigate damage by first using a good catalytic converter cleaner. If that doesn't work, you'll need to take the car to a repair shop to fix the problem, which will likely include the replacement of the part. The same in the case of the EGR.

Dirty Fuel Injectors:

This results in loss of power and frequent engine failures, motivated by inconsistent fuel intake. The nozzle cleaning should be done regularly to avoid this problem. Fortunately, it is a simple process using a dedicated cleaner. However, they can be so dirty that even the best cleaner may not work. In those cases, it's not a bad idea to replace them.

Defective Air Mass Flow (MAF) Sensor:

If you notice that the car is moving or shaking with increasing speed, it could be because this little piece is failing. Your job is to measure the amount of air entering the engine so that it can transmit this information to the car's brain (ECU). This then instructs the injectors to provide the right amount of fuel at the right time for proper mixing.

With a faulty MAF sensor, you may experience parasitic movements, especially driving at higher speeds, such as on the highway or highway where it would be most noticeable. The engine warning light should be present when the air mass flow sensor is operating incorrectly, although if this is not the case, it is something that can be easily confirmed with a computer with an OBD2 port and a specific program.

Worn Spark Plugs:

Speeding up more spark plugs that have already fulfilled their task will cause the engine to not start and not run as it should. This means that they don't ignite the fuel in each cylinder in a timely manner, causing the car to jerk when accelerating. Furthermore, it can also be much louder than normal. If the spark plugs are worn, they should be replaced, and their replacement is generally easy and inexpensive.

Defective Fuel Pump or Filter:

As we have seen above, when the correct amount of fuel is not delivered to the engine, it is often a tendency to notice jerks. In this case, a faulty fuel pump would have a hard time keeping up with fuel demands. Alternatively, you can have the fuel filter clogged, restricting its flow. Replacing it, like spark plugs, is easy and affordable.

Dirty Air Filter:

When not enough air reaches the combustion chamber, the problems are often the same as when there is not enough fuel. The air filter is the first line of defense against dirt and other foreign particles. A dirty unit will allow some of them to enter the motor, which will affect performance and cause some jolting. Check the condition of your air filter. If it is dirty, replace it.

Defective Ignition System:

In case the spark plugs are new and working well, it should be time to check your ignition system. New generation cars have ignition systems controlled by the engine ECU, so a failure in the ECU should be enough of a reason to take the car to your nearest service center for a mechanical checkup.

Defective Transmission Control Module (TCM):

If you drive an automatic transmission car and notice jerks just when there is a gear change, you may have a faulty Transmission Control Module (TCM). This part is responsible for the car knowing the relationship it has to engage when accelerating. These can be delayed or unpredictable and often abrupt, leading to something like a stumble. While it is not a common point of failure, it is worth considering.

Worn Throttle Cable:

While most cars already employ an electronic control system to accelerate, there are still many that have a physical cable that acts as a mechanical link between the pedal and the engine itself. Over time, it can wear down, causing the car to respond more slowly to acceleration and stumble rather than provide smooth acceleration. If damage to the exterior cladding is observed, it needs immediate attention.

The Skills with a Manual Transmission:

If you are not used to performing the pedal set in unison with the movement of the gear lever, it is very common to notice some jerk, mainly when you try to change from neutral to first or when you continue after a pause. Of course, the only solution is to practice. Foot movements, both when accelerating and releasing the clutch, greatly influence the smoothness of the ride.

Other Possible Reasons:

  • Too low mileage.
  • Leaks in vain.
  • Low quality gasoline.
  • Worn clutch.

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