Why does the automatic transmission car's engine speed increase but the speed doesn't when accelerating?
2 Answers
When an automatic transmission car's engine speed increases but the speed doesn't when accelerating, it is usually an issue with the automatic transmission. The most common cause is the torque converter not locking up. Symptoms of a torque converter not locking up: Normally, when the engine speed, vehicle speed, and throttle depth reach a certain level, the torque converter will lock up. If the torque converter fails to lock up, it often results in the engine revving without the car accelerating. This phenomenon mainly occurs in vehicles equipped with torque converters, such as all AT (automatic transmission) cars and some CVT (continuously variable transmission) models. Solution: For smooth and powerful acceleration in an automatic transmission car, it is necessary to press the accelerator more firmly. Whether the torque converter locks up depends not only on the vehicle speed but also on the engine speed and throttle depth. If you always press the accelerator lightly and drive at low speeds, the engine speed may not rise sufficiently, and the torque converter might not lock up.
I once encountered a situation where the RPM surged when I stepped on the gas pedal in an automatic transmission car, but the speed didn't increase. It happened on the highway, and it was really nerve-wracking. Later, I learned that it might have been due to transmission slippage or a problem with the torque converter. The engine was running, but the power wasn't being transmitted to the wheels, wasting energy and burning fuel. I immediately pulled over and found out that the torque converter's sealing ring had aged and caused a leak. After repairing it, everything was fine. In daily driving, I make sure to regularly change the transmission fluid for maintenance to prevent such failures. After all, safety is the top priority, and it's best not to let small issues escalate into big problems.
