Why does the car jerk when starting?

[MacAlyssa]

There are several reasons why a car may jerk when starting: 1. Jerking during acceleration and gear shifting in automatic transmissions: It is normal for automatic transmission cars to experience some jerking when starting. If you want to accelerate quickly while driving, you need to press the accelerator pedal deeply. At this time, the automatic transmission will automatically downshift to increase the engine speed. When the speed reaches a certain level, it will upshift. After upshifting, the speed will drop significantly, resulting in a relatively noticeable jerking sensation. 2. Damaged solenoid valve: A damaged solenoid valve is an important cause of jerking, which can be either occasional or fixed. The difference is simple: occasional jerking occurs without any pattern, while fixed jerking happens at a certain speed or when shifting gears at a fixed speed. 3. High transmission temperature: High transmission temperature can degrade the quality and friction characteristics of automatic transmission fluid, increasing friction and wear. This leads to transmission noise, and sludge (impurities or dirt) can also form inside the transmission (such as in the valve body), causing the transmission to jerk or experience impact.