Easy step by step guide on how automotive emissions systems work, though appearances
may vary, the process is the same for most vehicles.
Step 1 - The vehicle computer is responsible for
the emissions produced by the internal combustion
engine it controls. By using many
sensors such as an
mass air flow, which provide feedback data for the computer to analyze and adjust
engine emissions, which are controlled to within manufacturer specifications.
Step 5 - A
converter is utilized to expend un-burnt fuel in the exhaust system. The unit
is heated by exhaust gases as thermo reaction heats up to achieve the design goal
of lowering exhaust emissions. By using primary and secondary oxygen sensors the
efficiency of the catalytic
converter is monitored. An electric air pump is sometimes used to help heat
up the catalytic converters to optimize efficiency.
Step 6 - The
mass air flow sensor monitors airflow that enters the engine by measuring resistance
across a hot wire that is cooled while various amounts of air pass over it. This
feedback data trims the computers adjustments to further help clean emission output.