What Causes Jerking When Pressing the Throttle at Low Speeds?
3 Answers
The reasons for jerking when pressing the throttle at low speeds are: 1. Excessive carbon buildup in the throttle body, fuel injectors, and intake manifold; 2. Poor fuel quality leading to incomplete combustion; 3. Faulty spark plugs or ignition coils. The car's throttle is located on the far right and is also known as the accelerator or throttle valve. It is part of the vehicle's fuel supply system, controlling the engine's throttle opening to regulate air intake, while the computer adjusts fuel injection, thereby managing engine speed. Precautions for pressing the throttle include: 1. Apply and release the throttle pedal gently for smooth operation; 2. Coordinate clutch release with throttle input for quick and precise action; 3. Select appropriate gears to keep the engine running mostly at medium RPM and larger throttle openings for fuel efficiency; 4. Before stopping or turning off the engine, release the throttle pedal gradually and avoid sudden revving.
When I first encountered this issue, I thought the transmission was broken. Later, the mechanic told me that jerking at low speeds is mostly caused by ignition system problems. Worn spark plugs or leaking ignition coils can lead to engine misfires, especially after the car has been driven tens of thousands of kilometers. Another common issue is carbon buildup clogging the fuel injectors, which causes poor atomization and unstable fuel supply, particularly noticeable at low throttle. Another possibility is a dirty throttle body, causing the ECU to inaccurately control the air intake, resulting in uneven power delivery. It's recommended to first try replacing the spark plugs and cleaning the throttle body and fuel injectors—this is cost-effective but yields noticeable improvements. For older cars, it's also advisable to check the transmission fluid, as insufficient viscosity can worsen gear-shifting jerkiness.
My car used to jerk like riding a horse at low speeds when accelerating. After repeated inspections, I found it was actually caused by two minor issues combined. First, the fuel filter hadn't been replaced for too long, and impurities clogged the fuel line, resulting in insufficient fuel pressure. Secondly, there was a layer of oil sludge on the mass airflow sensor, causing it to misjudge the air intake, which led the ECU to incorrectly adjust fuel injection. The jerking was especially noticeable when the AC was on, as the engine was under greater load. Later, I replaced the fuel filter and cleaned the sensor with a specialized cleaner, and now the throttle response is much smoother. Don't overlook these small components during regular maintenance, and try to fuel up at reputable gas stations, as cheaper gasoline tends to have more impurities that can clog the fuel injectors more easily.
