Kylmäkäynnistysruiskut

Kylmäkäynnistysruiskut, often referred to as cold start injectors, are components found in older gasoline engine fuel injection systems. Their primary function is to enrich the fuel mixture during cold engine starts, facilitating smoother and more reliable ignition when the engine is at low temperatures.

When an engine is cold, fuel has a tendency to condense on the cold intake manifold walls and cylinder walls, reducing the amount of fuel that actually reaches the combustion chamber. This results in a lean mixture, which can cause hard starting, stalling, or rough idling. The kylmäkäynnistysruisku addresses this by delivering an extra burst of fuel directly into the intake manifold or cylinder head when the engine is cold.

The operation of a kylmäkäynnistysruisku is typically controlled by a thermotime switch or a similar temperature-sensitive device. This switch monitors the engine coolant temperature. When the temperature is below a certain threshold, it signals the cold start injector to open and inject fuel. As the engine warms up and reaches its optimal operating temperature, the thermotime switch deactivates the cold start injector, preventing an overly rich mixture and potential fuel wastage.

Modern fuel injection systems have largely eliminated the need for separate cold start injectors. This is because advancements in fuel injector design, engine control units (ECUs), and sensor technology allow for precise fuel metering and mixture control across a wide range of operating temperatures, including cold starts. However, understanding kylmäkäynnistysruiskut provides insight into the evolution of fuel delivery systems in internal combustion engines.