Muffler
Mufflers are usually treated during manufacturing with an anti-corrosive coating agent to increase the life of the product. The muffler reduces the level of noise produced by the engine, and also reduces the noise produced by exhaust gases as they travel from the catalytic converter to the atmosphere.
The EVAP system prevents fuel vapor build-up in the sealed fuel tank. Fuel vapors trapped in the sealed tank are vented through the vapor valve assembly on top of the tank. The vapors leave the valve assembly through a single vapor line and continue to the EVAP canister for storage until the vapors are purged to the engine for burning.
All applications required to meet on board diagnostics (OBD) regulations use the enhanced EVAP system. Some applications also incorporate an on-board refueling vapor recovery (ORVR) system. Refer to the appropriate Evaporative Emissions article for vehicle specific information on the description and operation of the evaporative emission system.