What is the reason for the left front door window of the Buick Excelle not being able to roll up or down?

[LaIsabelle]

Buick Excelle idling at 400 RPM is abnormal, Reasons for the abnormality: Idling refers to the engine running without load, only overcoming the internal friction resistance of its own components, without outputting power. The minimum speed required to maintain stable engine operation is called idle speed, which is one of the five basic operating conditions of an engine. A well-functioning engine usually idles at 550-800 RPM. If the vehicle idles at only 400 RPM, which is somewhat low, it is recommended to contact a 4S shop to check the engine's operating condition. Reasons for low idle speed: There are many reasons for low engine idle speed, such as issues with the idle speed control valve, carbon buildup in the throttle body, carbon buildup on the valves, clogged intake passages, clogged air filters, insufficient fuel injection pressure, etc. The engine's idle speed is regulated by the throttle body. During idle conditions, the throttle body maintains a very small opening, which is the idle operating condition.