Exhaust and Emissions
An exhaust system is a complex arrangement of parts and components that work in tandem to evacuate exhaust gases from the engine, while making them less harmful and noisy before they leave the exhaust system. A typical exhaust system of a modern vehicle consists of an exhaust manifold, a catalytic converter, a muffler and a tailpipe.
When an internal combustion engine is running, it produces a variety of byproducts. Some of them are harmless, while others, such as nitrogen oxide, carbon monoxide and hydrocarbons are dangerous to human beings and to the environment. The job of an emissions system is to lower the amount of harmful pollutants in the exhaust gases before they escape into the atmosphere. It also helps for improving engine performance by redirecting a small amount of exhaust gases back into the combustion chamber.
Evaporative control (EVAP) system
An evaporative control system gathers fuel vapors from a fuel tank to prevent damage to the fuel system of a vehicle. Depending on the engine load and its operating temperature, it can also purge fuel vapors into the engine to increase its fuel efficiency and overall performance.
An EGR system, short for an exhaust gas recirculation system, transfers a small amount of exhaust gases into the combustion chamber through the intake manifold. The exhaust gases mix with an air/fuel mixture, reducing combustion temperatures, which prevents nitrogen oxide formation and makes exhaust gases less harmful.
Secondary air injection system
Its primary job is to force some fresh air into the exhaust system in order to reduce emissions.