Evaporative Emission Control System Operation Description. Oldsmobile Shelby Series 1 1999

For 1990-2009 cars

The evaporative emission (EVAP) system contains the following components:

• | The EVAP fuel vapor canister

• | The EVAP purge solenoid valve

• | The EVAP vent valve

• | The EVAP fuel tank pressure sensor

• | The fuel tank

• | The fuel vapor and vent lines

The powertrain control module (PCM) will command the EVAP purge solenoid valve ON to purge stored fuel vapors from the EVAP fuel vapor canister. The PCM will pulse width modulate the on-time of the solenoid in order to regulate the amount of fuel vapor entering the engine. The PCM will enable purge during most driving conditions, including idle based upon sensor inputs. The PCM runs a comprehensive diagnostic test of the EVAP system. A failure of the EVAP system will set a DTC. The EVAP vent valve and the EVAP fuel tank pressure sensor are needed by the PCM to diagnose the EVAP system.