Auto Systems and Repair: Exhaust and Emissions
Exhaust systems reduce the amount of noise produced by the engine and channel the high-temperature, poisonous exhaust gases from the engine by safely routing them under the vehicle. Then, through a system of manifolds, pipes, and sound-absorbing mufflers, the gases are released out of the back of the vehicle.
During normal vehicle operation, emissions are produced. While some of these emissions are harmless like water, heat, and oxygen, harmful byproducts—hydrocarbons (HCs), carbon monoxide (CO), and nitrogen oxide (NOx)—are also produced. One way the system reduces these harmful byproducts is by making the engine run more efficiently. The emissions system also recycles emissions back through the combustion process or converts them into harmless gases.
The evaporative control (EVAP) system captures any raw fuel evaporating from the fuel storage system. Under precise operating conditions dictated by engine temperature, speed, and load, the EVAP system purges these captured fuel vapors back into the combustion process. More >>
The exhaust gas recirculation (EGR) system recycles a small amount of exhaust gas from the exhaust system and mixes it with the intake manifold air going into the combustion chambers. The addition of this inert (or non-combustible) exhaust gas limits the peak combustion temperatures to a point before the formation of nitrogen oxide (NOx) is known to occur. More >>
Secondary Air Injection System
The secondary air injection system pumps fresh air into the exhaust system to help reduce exhaust emissions. More >>
Additional Key Parts
Exhaust manifold, Catalytic converter, Muffler, Tail pipe, Oxygen sensor, Air pump, Air pump check valve, Powertrain control module, Canister purge valve, Canister vent valve, Charcoal canister, EGR cooler, EGR position sensor, EGR solenoid