What Causes Low Car Idle Speed?

[LeIris]

The reasons for low car idle speed are: 1. Uneven fuel injection quantity and poor atomization from the injectors, causing power imbalance among cylinders, resulting in unstable idle speed when the engine is cold; 2. Low fuel pressure leading to poor fuel atomization or linear fuel injection from the injectors, severely only dripping fuel, reducing injection quantity and making the mixture too lean, causing unstable idle speed when the engine is cold; 3. Temperature sensor, oxygen sensor, or circuits failing to respond promptly, causing the control unit to issue incorrect commands, resulting in incorrect fuel injection quantity and making the mixture too rich or too lean, causing unstable idle speed when the engine is cold.