What Causes a Sudden Increase in Idle Speed During Cold Start?

[OElliana]

Cold start idle speed suddenly increasing is a normal phenomenon. To allow the engine to reach its optimal operating temperature as quickly as possible, the engine idle speed is increased based on signals from sensors like the coolant temperature sensor during a cold start. After the engine warms up, the engine speed will gradually decrease to around 800 to 1000 RPM. The normal idle speed for a cold start is generally between 700 to 800 RPM. If the idle speed is too low, the engine may vibrate easily, and if it's too high, fuel consumption will increase. The idle speed of a car refers to an operating condition where the engine runs without load, known as idling, meaning the car is in neutral gear. The engine speed during idling is called the idle speed, which can be adjusted by modifying the throttle opening size, among other methods.