if i understand your question correctly, your asking how catalytic converters work?

brb

here goes:

state which emissions the system controls

nitrates of oxygen and carbon monoxide and to a lesser degree carbon dioxide.

explain how the emissions are controlled

the platinum and rhodium and in some cases gold attract the nitrogen away from the N02 resulting in a reduction of nox and an increase in 02.

the high temperature present in a cat burns the excess hydrocarbons thus reducing carbon monoxide

if i understand correctly,

two additional emission control systems are 02 sensors which control emissions by keeping the air/fuel mixture as close to ideal as possible resulting in complete combustion and air injection which injects additional air into the exhaust stream again resulting in as complete combustion as possible particularly when the engine has not reached operating temperature so is much less efficient or 'dirty' if you will.

does that help?

ok, your right egr would be a fourth emissions system.

pretty simple really if you think of exhaust as an inert gas that uses up space thus reducing the amount of air and fuel in the engine, thats about it.

air injection primarily burns up all the extra fuel needed so the engine will run well cold.

you've given me quite an education just thinking about these things after all these years, thanx, gary

please dont forget to click accept and good luck

a is easy all emissions systems are controlling nox, hc, and co and to a lesser degree c02

thought i pretty much covered the cat

air injection is used to burn up the excess hc used with a cold engine

egr injects an ineert gas during decel.

pretty straightforward.

gary