Is it normal for the engine to run at high RPM when just started?
2 Answers
It is normal for the engine to run at high RPM when started. The car needs high RPM to allow the engine to quickly reach normal operating conditions, requiring a richer air-fuel mixture, increased air intake, and fuel injection, resulting in higher RPM. Cold weather lowers the water temperature, causing the engine idle speed to increase. Depending on the water temperature, the cold engine idle speed will gradually decrease from over 1200 RPM until the engine reaches the normal operating temperature, stabilizing at the standard idle speed of around 800 RPM. High RPM is generally caused by excessive carbon deposits, and timely cleaning of the throttle valve can resolve the issue. Other reasons for high engine idle speed include: 1. Idle switch not closing; 2. Faulty idle control valve; 3. Air intake pipe leakage; 4. Incorrect valve timing; 5. Fuel injector dripping or clogging; 6. Exhaust system blockage; 7. EGR valve opening during idle conditions.
Oh, high engine RPM right after startup is super common! My own car does the same thing, especially after sitting overnight in winter when the tachometer jumps to around 1500 RPM. This is actually thoughtful engineering: the engine needs to warm up quickly to get oil circulating for lubrication, and the catalytic converter must reach operating temperature to clean exhaust gases. I usually wait 30-40 seconds until the RPM sound decreases before shifting into gear - this protects the engine and saves some fuel. If the RPM still hasn't dropped after five minutes of cold start, there might be an issue - like a dirty mass airflow sensor or faulty coolant temperature sensor. In that case, I'd recommend heading to the repair shop for a checkup immediately.
