What Causes High Engine RPM When Going Downhill?

[ElizaMarie]

High engine RPM when going downhill is caused by the following reasons: Driving from a higher to a lower elevation gives the vehicle potential energy due to gravitational acceleration. Even without pressing the accelerator, the vehicle will accelerate when going downhill. However, the engine's reverse traction force will slow the vehicle down. When the slope is steep, the gravitational acceleration acting on the vehicle will exceed the engine's reverse traction force in the current gear, causing the RPM to rise. Precautions when going downhill: 1. Do not rely solely on low gear to control speed. To avoid overheating the brake pads from prolonged braking, engine braking is used, but this does not mean you should not use the brakes at all. Even if the gear is fixed in a low position, if the slope is steep and long, the engine RPM may still be forced to increase. In such cases, you should use the brakes to assist in slowing down. 2. Engine braking methods for automatic transmissions. For automatic transmissions, engine braking requires shifting to L (Low) or S (Sport) mode in manual mode to fully utilize engine braking for speed control.