Cold Start Injector: Description and Operation

Cold Start Valve:

DESCRIPTION:

The Cold Start Valve is a non-ECM controlled solenoid operated valve used to provide fuel during the "Starting Mode". It is mounted to the intake manifold and is controlled by a coolant temperature switch. The cold start valve is different from a port injector in that it is not pulsed, instead, it is either on or off.
Fuel from the cold start valve is sprayed into the passage in the intake manifold where it mixes with air from the Idle Air Control (IAC) Valve, and is directed through branch passages to the cylinder ports. By injecting the fuel further back from the cylinders, and adding air to the fuel, the mixture is highly vaporized before entering the cylinders and provides a more combustable mixture for improved cold starting.

Cold Start Valve Assembly:

OPERATION:

Fuel delivery from the cold start valve occurs only during cranking, and only when the engine coolant temperature is below 35° C (95° F). The cold start circuit receives it's power directly from the starter solenoid, and is protected by the crank fuse. The cold start fuel injection switch (thermo-time switch) provides the ground path for the circuit. It is a bimetal switch which opens the circuit at a specified coolant temperature. The bimetal is also heated by the winding in the switch which would allow the valve to stay "ON" 8 seconds at -20° C or below. The time the switch stays closed varies inversely with coolant temperature. In other words, as the coolant temperature goes up the maximum cold start valve "ON" time goes down.