Is It Normal for a New Car to Have High RPM When Starting?
1 Answers
It is normal for a new car to have high RPM when starting. The car needs high RPM to allow the engine to quickly reach normal operating conditions, requiring a richer air-fuel mixture. As a result, both the intake air volume and fuel injection quantity increase, leading to higher RPM. After the engine runs for a while, the RPM will drop to normal levels. More details are as follows: 1. The car's ECU adjusts the fuel injection quantity based on signals from the coolant temperature sensor to meet the engine's varying fuel demands under different operating conditions. The colder the weather and the lower the coolant temperature, the greater the difference from the normal engine operating temperature, and the higher the idle speed controlled by the ECU, meaning the engine RPM will be higher when starting. 2. Under normal circumstances, depending on the coolant temperature, the engine's cold idle speed will gradually decrease from over 2000 RPM until the engine reaches the normal operating temperature, stabilizing at the standard idle speed of around 800 RPM. 3. Abnormal high RPM in a car is usually caused by excessive carbon buildup, which can be resolved by timely cleaning of the throttle body and idle air control valve. Other reasons for high idle RPM include: 1. Idle switch not closing; 2. Faulty idle control valve; 3. Intake manifold leakage; 4. Incorrect valve timing; 5. Fuel injector dripping or clogging; 6. Exhaust system blockage; 7. EGR valve opening during idle conditions.
