First of all, the Evaporative Emission Control System (EECS) captures fuel vapor from the fuel tank, throttle body, and intake manifold. It consists of a charcoal-filled canister connected to the fuel tank, a ported vacuum, and an intake manifold vacuum. When the engine is off, the system holds fuel vapors in the canister. During engine operation, a purge control solenoid is opened to release the fuel vapors into the combustion process. A faulty purge control solenoid, damaged canister or hose problems can result to issues like poor idle, stalling or driveability problem. If necessary, the technician checks if there are any cracks in the canister and replaces it accordingly.