To make the engine work properly and produce low emissions, carburetors or fuel injectors are used to mix the air and fuel to the optimal amount that the engine requires. As the engine burns the fuel, it makes emissions. Nitrogen gas, carbon dioxide, and water vapors are the main emissions; additionally the engine produces emissions of carbon monoxide, hydrocarbons and nitrogen oxides in smaller amounts. .
Catalytic converters are used in order to stop or reduce these emissions. The two types of catalytic converters are two-way and three-way. A two-way converter converts carbon monoxide to carbon dioxide while it turns unburned hydrocarbons to carbon dioxide and water vapors. The three-way converter works the same way as the two-way converter. However, a three-way also reduces nitrogen oxide into nitrogen and oxygen (Halderman Automotive 145). .
Oxygen sensors and the PCM also play an important part in reducing the emissions in a vehicle. The oxygen sensor is located in the exhaust pipe, and it detects the amount of oxygen in the exhaust and sends the information to the PCM. The PCM then adjusts the amount of fuel entering the engine. These two components help to reduce emissions by not letting the engine run on lean or rich mixtures that produce more emissions. In newer models of manufactured vehicles, a wide band oxygen sensor is used instead of conventional oxygen sensors. The wide band oxygen sensor acts as an air-fuel ratio (AFR) sensor, wide range air-fuel (WRAF) sensor, lean air-fuel sensor, and a general air fuel sensor. A wide-band oxygen sensor is capable of measuring air-fuel rations as rich as 10:1 and as lean as 23:1; this data helps the PCM achieve more reduced combustion emissions" (Halderman Automotive 210).
Evaporative emissions systems are used to reduce the evaporation of hydrocarbons in the atmosphere. Positive crankcase ventilation (PCV) and a carbon canister in the fuel tank are used in the EVAP system to reduce emissions.
