Why does an automatic transmission car not move in reverse without pressing the accelerator?
2 Answers
Automatic transmission cars do not move in reverse without pressing the accelerator because the power transmission between the engine and the transmission in an automatic vehicle relies on a torque converter. When reversing or moving forward, if the car is driven at idle speed, the engine's power output is insufficient to overcome the frictional resistance from the ground, preventing the car from moving in reverse or forward. Automatic transmission typically refers to a car's automatic gear-shifting mechanism, where the transmission control system automatically selects the appropriate gear based on the engine's speed and load, replacing the driver's subjective judgment of timing and gear-shifting operations. Generally, automatic transmission cars have six gear positions, arranged from top to bottom as: P, R, N, D, S, and L.
I used to drive an automatic transmission car, and it often wouldn't move in reverse without pressing the accelerator. This is usually because the idle speed is too low. When the engine is idling in neutral, if the RPM isn't high enough, there isn't sufficient power to move the car backward. Common causes could be excessive carbon buildup in the throttle body, restricting airflow and preventing the RPM from rising; or transmission issues, such as an aging torque converter or insufficient transmission fluid, affecting power delivery. I've encountered this situation, especially noticeable during cold starts or in older car models. The solution is to start with simple checks: cleaning throttle body carbon deposits or changing transmission fluid can improve the condition. Avoid forcefully stomping on the gas pedal, as it can easily damage the engine. Regular maintenance, including periodic cleaning of key components, can prevent such minor issues. If the problem persists, it's best to get a professional diagnosis at a repair shop promptly to avoid turning a small issue into a major problem.
