What Causes Unstable Idle and Stalling When the Engine is Warm While It's Normal When Cold?

[FaithLynn]

Unstable idle and stalling when the engine is warm are mainly caused by air leaks in the intake system, low fuel pressure, clogged air filters, poor fuel injector atomization, fuel leaks, or blockages. Below are the relevant explanations: 1. Normal Idle: When the vehicle is parked and the engine is started, the minimum stable operating speed of the engine is called parking idle (the process of the engine transitioning from a cold idle state to an idle state at normal operating temperature is called warm-up or heating). 2. Driving Idle: When the car is in gear, without pressing the accelerator pedal or releasing it while driving, maintaining the minimum throttle opening, the engine speed matches the parking idle speed, which is referred to as driving idle.