What Causes a Sudden Increase in RPM During Constant Speed Driving?
2 Answers
It is likely due to engine knocking, and it is recommended to have it inspected at a repair shop. Below is relevant information: 1. Engine: An engine (Engine) is a machine that can convert other forms of energy into mechanical energy, including internal combustion engines (reciprocating piston engines), external combustion engines (Stirling engines, steam engines, etc.), jet engines, electric motors, etc. Internal combustion engines typically convert chemical energy into mechanical energy. 2. Knocking: Under certain conditions (such as excessively high compression ratio), the combustion in a gasoline engine can become abnormal, with pressure curves showing high-frequency and large-amplitude fluctuations. At this time, the flame propagation speed and the shape of the flame front change drastically. This phenomenon is called detonation, and knocking is the external manifestation of detonation.
I've experienced sudden RPM surges while driving at a constant speed, usually because the automatic transmission misjudged road conditions and downshifted automatically, such as mistaking slight resistance on a flat road for needing acceleration. Another possibility is a faulty throttle position sensor causing the engine to inject more fuel, or transmission fluid that's too dirty and needs replacing. Sometimes the electronic control unit acts up and temporarily adjusts the RPM erratically. RPM surges not only waste fuel but can also lead to overheating and engine damage. So when it happens, slow down and pull over, avoid long-distance driving, and visit a repair shop as soon as possible to check for error codes with a diagnostic tool. Developing a habit of regular transmission fluid changes can help prevent this issue.
