What are the causes of difficult cold starts in engines?

[McJake]

The causes of difficult cold starts in engines are: 1. Air leaks in the intake system; 2. Fuel pressure is too low; 3. Clogged air filter; 4. Faulty coolant temperature sensor; 5. Faulty mass airflow sensor; 6. Malfunctioning idle control valve or auxiliary air valve; 7. Cold start injector not working; 8. Fuel injector leakage; 9. Incorrect ignition timing; 10. Broken wiring from the starter switch to the ECU; 11. Cylinder compression pressure is too low. Methods to address starting difficulties include: 1. Check the battery condition; 2. Use suitable engine oil; 3. Replace spark plugs promptly. Methods for warming up the engine: 1. Drive after 30 seconds to 1 minute of idling; 2. Maintain low-speed driving; 3. Once the engine reaches normal operating temperature, drive as usual.