EVAPjärjestelmän

EVAPjärjestelmän refers to the Evaporative Emission Control System, a critical component in modern internal combustion engine vehicles designed to prevent the escape of volatile organic compounds (VOCs) from the fuel system into the atmosphere. This system is mandated by environmental regulations in many countries to reduce air pollution.

The EVAP system works by capturing fuel vapors that naturally evaporate from the fuel tank and fuel lines. Instead of venting these vapors directly into the air, they are stored in a charcoal canister filled with activated charcoal. This charcoal absorbs the hydrocarbons. When the engine is running under specific operating conditions, the engine control module (ECM) opens a purge valve, allowing the stored vapors to be drawn into the engine's intake manifold. Once in the manifold, these vapors are mixed with the air-fuel mixture and burned during the combustion process, effectively eliminating them as emissions.

Key components of an EVAP system include the fuel tank, fuel filler neck, vapor lines, charcoal canister, purge valve, vent valve, and the ECM which controls the system's operation. The ECM monitors the system for leaks using various methods, such as applying a slight vacuum or pressure to the system and checking for pressure drops. If a leak is detected, a diagnostic trouble code (DTC) is typically set, and a "check engine" light may illuminate on the dashboard. Regular maintenance of the EVAP system is important for proper functioning and to avoid potential emissions-related issues.