What Causes Unstable Engine Idling?

[Eric]

The reasons for unstable engine idling are: 1. Excessive oil deposits and carbon buildup in the throttle body; 2. Weak spark due to faulty spark plugs; 3. Blocked fuel lines or faulty intake pipes; 4. Sensor malfunctions causing the ECU to lose control; 5. Blown fuses or faulty ignition modules; 6. Poor fuel quality. The solutions for unstable engine idling are: 1. Clean or replace the idle control valve and use a specialized decoder for basic idle settings; 2. Locate and seal leaks or replace affected components; 3. Adjust or replace the throttle position sensor; 4. Clean and inspect each fuel injector's spray volume to ensure no blockages or leaks; 5. Remove carbon buildup from the EGR valve or replace the EGR valve.