What are the causes of jerky movement in a car?
3 Answers
The causes of jerky movement in a car are: 1. Dirty fuel injectors and throttle body; 2. Excessive carbon buildup in the throttle body, leading to insufficient air supply; 3. Aging spark plugs; 4. Poor quality engine oil. The fuel injector is essentially a normally closed valve. When the electromagnetic coil is energized, it creates a magnetic force that lifts the needle valve, opening the injection port. Fuel is then sprayed at high speed through the annular gap between the needle valve head and the injection port, forming a mist that facilitates complete combustion. The throttle body is a controllable valve that regulates the air entering the engine, available in two types: traditional cable-operated and electronic throttle. The spark plug's function is to discharge the high-voltage pulse sent by the high-voltage wire, breaking down the air between the two electrodes of the spark plug to generate an electric spark, thereby igniting the air-fuel mixture in the cylinder.
When driving an automatic transmission car, I experienced jerking sensations during acceleration, as if the car was being held back and stuttered a few times, which might be related to the transmission. Dirty or insufficient transmission fluid can cause rough shifting, and clogged oil passages can affect the valve body. Once, when I took it to a repair shop for inspection, the mechanic said the fluid needed changing because it had degraded after tens of thousands of kilometers. Now, I make sure to perform regular maintenance and use high-quality fluid to minimize issues. Driving habits also play a key role—sudden hard acceleration can easily lead to jerking, so maintaining a steady speed is advisable. Occasionally, tire pressure or suspension problems may contribute, but this is less common. If the issue persists, it’s best to consult a professional early to avoid further damage to components.
Experiencing jerking with a manual transmission is quite common. When I drive my own car, I feel uneven acceleration, as if the clutch is slipping. Power interruption can be caused by clutch wear or improper operation, such as incorrect shifting timing or inaccurate RPM matching. In older cars, the clutch disc becomes thinner with prolonged use, causing the clutch to not engage tightly when pressed, leading to jerking. Fuel system issues, such as unstable fuel supply from the fuel pump, can also contribute. Practicing smooth shifting and synchronization can help reduce jerking. During maintenance, check the clutch system and replace parts if necessary. A simple test is to accelerate slowly on a flat road; if there's no jerking, it's likely due to human factors.
