What causes unstable idle speed for a few seconds after starting the car?

[HoldenMarie]

It's quite normal for the idle speed to be unstable for a few seconds after starting the car. Here are the relevant explanations: 1. Principle: When the car is cold, the vehicle's computer system detects low water temperature and opens the throttle valve wider to increase air intake. As the water temperature rises, the throttle valve gradually returns to normal. This is essentially the computer system performing fuel correction. 2. Expansion: During open-loop control of the system, fuel correction involves a fixed basic injection pulse width corresponding to the air volume measured by the air flow sensor or the load measured by the intake manifold absolute pressure sensor, while considering factors like engine temperature and engine speed to adjust the pulse width.