What are the reasons for difficult cold starts in cars?

[McAlivia]

The reasons for difficult cold starts are as follows: 1. Excessive carbon deposits. Especially at the throttle body. If there is too much carbon buildup at the throttle body, it affects the precision and smoothness of engine intake. In severe cases, it can even cause the throttle to stick, preventing acceleration. Cleaning is required. 2. Faulty coolant temperature sensor. Although the component is small, it can cause the engine control unit to misjudge, resulting in reduced fuel injection. This leads to insufficient engine power, making it difficult or even impossible to start the engine. 3. Insufficient fuel pressure. Fuel pressure can be measured. When the ignition is turned on without starting the engine, the fuel pressure should be around 0.3MPa; when the engine is started and idling, the fuel pump pressure should be around 0.25MPa. If the gasoline contains too much water or impurities, it can damage the fuel pump internally, leading to insufficient fuel supply. 4. Small valve clearance. After driving a certain number of kilometers, wear between the valves and the transmission mechanism can cause changes in valve clearance. If the valve clearance is too small, the car will be hard to start.