What Causes the Sudden Jerk When Starting an Automatic Transmission Car?

[StRichard]

The sudden jerk when starting an automatic transmission car can be attributed to the following reasons: Reason 1: Internal clutch pressure leakage in the transmission. Reason 2: Blockage or poor flow in the transmission oil passages. This may be caused by wear in the valve body or prolonged intervals between transmission fluid changes, leading to reduced lubrication effectiveness. Reason 3: Incorrect transmission fluid level. Both insufficient and excessive transmission fluid can cause jerky starts in automatic transmissions. Reason 4: Sludge buildup in the transmission fluid can clog the oil passages in the valve body during circulation. Over time, this can lead to a series of transmission issues such as overheating, harsh shifting, and slipping.

[VanRiley]

As someone who frequently works on car repairs, the issue of sudden jerking when starting an automatic transmission is quite common. Most of the time, it's due to a problem with the torque converter in the transmission, such as low or dirty transmission fluid. Degraded fluid can affect the smoothness of power delivery. When you press the accelerator, the car might misinterpret it as a high demand for acceleration, causing it to lurch forward suddenly. Other possible causes include issues with the throttle position sensor—if it's making poor contact or has aged, it can send incorrect signals—or excessive carbon buildup on the throttle body, which can affect air intake and engine response. I recommend first stopping the car to check the condition and level of the transmission fluid, or trying to clean the throttle body. If these steps don’t resolve the issue, it’s best to take the car to a professional repair shop to diagnose the internal condition of the transmission. Ignoring this problem can lead to gear wear or increased fuel consumption, and over time, it may affect the overall performance of the vehicle.

[Roger]

When I first started driving, I experienced sudden jerks when starting an automatic transmission car. At the time, I thought there was a major problem with the car, but later realized it was due to driving habits. It might have been because I pressed the accelerator too quickly or accelerated before fully releasing the brake, causing the engine RPM to spike suddenly. Another factor could be a stuck throttle pedal or sensor malfunction, which is particularly common in older cars due to aging and imprecise responses. I tried adjusting my method, such as pressing the accelerator slowly when starting to allow the car to move smoothly, and indeed, the issue improved. If the driving technique isn't the problem, it might involve transmission issues, such as abnormal torque converter operation or control module software errors. I recommend beginners practice starting more often and regularly inspect the throttle system to avoid dangerous situations. Driving safety comes first—small issues left unaddressed can easily escalate into major problems.

[DelVanessa]

As a car enthusiast, I analyze that the root cause of automatic transmission's sudden jerking during acceleration lies in the imbalance between engine and transmission coordination. Possible issues include the engine's intake system malfunction, such as a throttle body clogged with carbon deposits, leading to uncontrolled power output when accelerating; or deteriorated transmission fluid affecting lubrication. Simple solutions involve cleaning the throttle body and replacing the fluids, which can significantly improve performance. If symptoms persist, it might be due to sensor misreporting or circuit shorting, requiring professional diagnostics. Timely vehicle maintenance can extend component lifespan.