问：发动机闲置波动和死亡。

Hi There! It sounds like you may have a dirty or failing idle air control valve causing your engine idle to fluctuate and eventually stall. In the mornings it is normal for the engine idle to be a bit higher than normal when you start the car as this is the cold start enrichment process which allows the engine to warm up sufficiently, however this should cause the RPM’s to hover around 1,200-1,500 or so, not 3,000.

The idle air control valve is a small valve on the engine’s intake system that reads the air intake as it comes into the motor. This is controlled by the car’s ECM which uses this information to make adjustments to the air/fuel ratio depending on various inputs such as outside air temperature, intake air temperature, load and various other things. As you accelerate, your car’s engine is receiving a much higher dose of fuel than when at idle and conversely, when you let off the gas pedal, there is a sudden change in this fuel supply as a result of your foot letting off the pedal. When this happens, the job of the idle air control valve is to bring this deceleration down to a slow and smooth idle rather than suddenly cutting off the fuel supply causing the motor to die. When theidle air control valve无法正常工作，这会导致此过程中断，从而导致发动机无法正确闲置。我建议让专业人士来您的位置诊断和检查您的车辆。