What Causes High Engine RPM in Cars?
2 Answers
The reasons for high engine RPM in cars are: 1. Fault in the intake system, sudden increase in throttle opening; 2. Insufficient cylinder pressure, check for piston ring and piston wear; 3. Issues with engine oil; 4. Slippage or damage to the air conditioning clutch, causing the engine to suddenly lose load and RPM to increase; 5. Forced downshift by the transmission computer or internal transmission failure; 6. Insufficient engine power output. The level of engine RPM relates to the number of work cycles per unit time or the effective power of the engine, meaning the effective power of the engine varies with different RPM levels. During idle, the engine RPM typically reaches around 700 RPM per minute, and during normal operation, it can reach up to 3000 RPM per minute.
Over the years of driving, I've encountered several instances of sudden RPM surges, especially when waiting at red lights with the engine roaring loudly. The most common causes include a stuck throttle pedal or floor mat jammed underneath it, making the car think I'm accelerating; a dirty mass airflow sensor sending incorrect signals, leading to excessive fuel injection; a faulty idle control valve causing RPM fluctuations, particularly after a cold start; a vacuum leak drawing in extra air, prompting the ECU to compensate by increasing fuel and raising RPM; and in manual transmission cars, clutch slippage making the engine work hard without a corresponding increase in speed. These issues also affect fuel consumption and noise levels. I recommend first checking pedal flexibility and cleaning the throttle body. If that doesn't help, it's best to visit a shop to scan for trouble codes.
