Cold Start Injector: Functions and How it Works

Cold Start Injector: Functions and How it Works - In engines that carry EFI (Electronic Fuel Injection) technology, the flow of the fuel is controlled electronically. The EFI engine has advantages in addition to producing high power, efficiency in fuel consumption, and being environmentally friendly.

The use of temperature sensors makes EFI vehicles easier to start. However, on injection vehicles, some of the engines are also equipped with additional injectors, namely cold start injectors. As the name implies, this component will play a role when the engine is cold. The control of the cold start injector is carried out by the cold start injector time switch. This component will regulate the volume of fuel injected by adjusting the injection time.

Cold Start Injector Function

The function of the cold start injector is to improve engine starting (starting the car for the first time).

During cold start the injector will inject fuel into the intake camber when the cooling water temperature is still low in order to improve engine performance. So even in cold conditions the vehicle becomes easy to start.

How Cold Start Injectors Work

On some EFI engines, the cold start injector will work as long as the engine is starting and the cooling water temperature is still low, the duration of fuel injection by the cold start injector is limited by the start injection time switch, to prevent fuel pooling.

When the ignition switch is turned to the ST position, current flows to the solenoid coil. The current flowing through this coil will cause an electromagnetic force and make the plunger pulled against the spring pressure, then the valve will open and the fuel will flow through the end of the injector.

Cold Start Injector Electrical Circuit

When the water temperature is still cold, the contact will be closed, if the ignition is in the ST position, the current will flow as below and the fuel will be injected.

When the ignition is in the ON position after the engine is started, injection from the cold start injector will end, if the starter motor rotates for a long period of time allowing fuel to pool (the spark plug gets wet), therefore, when current flows through the heat coil (1 ) and (2) the bimetallic element becomes hot and the contacts open so no current flows to the cold start injector, so that if the engine is difficult to start, fuel pooling can be prevented. So to prevent fuel pooling, the bimetallic element heated by the heat coil (2) will keep the contacts from closing.

Based on the above, the cold start injector concept is basically the same as the choke system on the carburetor where the function is the same to inject or add more fuel into the cylinder when the vehicle is starting (coolant water temperature is still low). With the intention that the engine is easier to start and can quickly reach the engine working temperature.