A cold start injector is a specialized fuel injector designed to help an engine start in cold temperatures. It works by spraying extra fuel into the intake manifold or a dedicated cold start port to create a richer air-fuel mixture, making ignition easier when the engine is cold.
How It Works:
- Temperature Sensor Activation:
- The cold start injector is controlled by a thermo-time switch or engine control unit (ECU), depending on the system.
- If the coolant temperature is below a certain threshold (e.g., below ~50°F or 10°C), the switch allows the injector to operate.
- Fuel Injection:
- When the engine is cranking, the cold start injector opens and sprays additional fuel into the intake manifold or near the intake valves.
- The fuel is atomized to improve combustion, making it easier for the engine to start.
- Timed Operation:
- The thermo-time switch ensures that the injector only sprays for a limited time (typically 5-10 seconds) to prevent over-fueling or flooding.
- Once the engine warms up, the cold start injector is deactivated.
Key Components:
- Cold Start Injector (separate from main injectors)
- Thermo-Time Switch (temperature and time control)
- Engine Control Unit (ECU) (in modern systems)
- Fuel Rail Connection (receives fuel from the main fuel system)
Common Issues:
- Injector Clogging: Dirt or deposits can block the injector, leading to hard starts.
- Stuck Open Injector: Causes excessive fuel consumption and rough running.
- Faulty Thermo-Time Switch: May prevent the injector from operating properly.
Many modern engines have eliminated cold start injectors, instead relying on advanced ECU programming and multi-port fuel injection to manage cold starts efficiently.