Why is it difficult to start a car even when the battery is charged?
Although the electricity used by a car after starting is supplied by the alternator, all the electricity used when the car is switched off is supplied by the battery, including the large amount of energy needed to start the car. If the battery is low on charge, the car will be difficult to start, or may not start at all, in which case a car jump starter is needed. Therefore, when encountering starting difficulties, we first think of the car’s battery. However, besides the battery, there are four other components in a car that, if malfunctioning, can also cause starting difficulties.
I. Throttle Body
Listing the throttle body as a car component is actually just a representation of the intake system’s working condition. Carbon buildup and dirt on the throttle body over time can block it, affecting the throttle opening. The throttle body is the only passage for engine intake air; blockage leads to a rich fuel mixture, causing difficulties in cold starting, unstable idling, and shaking. Throttle body cleaning is also a car maintenance item; it needs cleaning when it gets very dirty.
II. Carbon Canister
Just mentioning the carbon canister is a bit narrow; accurately speaking, it should be the carbon canister system, which consists of the carbon canister and the carbon canister solenoid valve (the solenoid valve being constantly open or closed can lead to two different fault phenomena). The carbon canister is an important but often overlooked component. It’s installed outside the fuel tank, between the fuel tank and the engine, and is generally a can-shaped structure with three pipes, making it easy to find. The main function of the carbon canister is to use activated carbon to adsorb volatile gasoline, preventing gasoline from evaporating into the atmosphere and polluting the environment. After the engine starts, these fuels are sent back into the intake manifold to participate in combustion, playing a role in energy saving and environmental protection. If the carbon canister system malfunctions (such as a carbon canister solenoid valve malfunction), it will directly affect the air-fuel ratio when the car engine starts, causing difficulty in starting. This phenomenon mainly occurs in hot weather. In hot weather, especially when the car is exposed to direct sunlight, gasoline evaporates more intensely, and the pressure of gasoline vapor is greater. At this time, a carbon canister system malfunction will cause difficulty in starting in hot weather, but the fault phenomenon will be reduced or even disappear in cold weather. This makes it difficult to find the cause, but it’s actually the carbon canister system “causing the trouble.” To extend the service life of the carbon canister, we should avoid overfilling the fuel tank when refueling, leaving a buffer space for gasoline vapor, especially in hot weather, to relieve the pressure on the carbon canister.
III. Water Temperature Sensor
The water temperature sensor, as one of the representatives of various engine sensors, is the sensory nerve of the engine’s brain—the engine control unit (ECU). If the water temperature sensor malfunctions, the ECU cannot correctly identify the temperature of the cooling water, not knowing whether the engine is cold or hot, and cannot provide the correct air-fuel ratio, resulting in an imbalance in the fuel mixture ratio. For example, during a cold start, the ECU might still be using the temperature signal from when the engine was warm, leading to a lean fuel mixture and causing difficulty in starting the car in cold conditions.
IV. Spark Plugs
Spark plugs are listed here because they are a crucial component of the ignition system. Like ignition coils and high-voltage wires, problems with spark plugs can cause ignition failures in the fuel mixture. However, spark plugs are more prone to failure than ignition coils and high-voltage wires.
Each cylinder has a spark plug, and a spark plug failure generally results in misfiring in that cylinder, leading to symptoms such as difficulty starting, increased fuel consumption, reduced engine power, engine vibration, and excessive emissions. Spark plugs are wear-and-tear parts and require preventative replacement according to their service life. Furthermore, spark plugs are prone to failure; carbon buildup can cause spark plug malfunction, although cleaning can restore their functionality.
