The concentration of hydrocarbons in the crankcase and fuel tank can be many times higher than the concentration of hydrocarbons recorded in the exhaust gas.
Crankcase ventilation system (pic. 5.27) The engine directs crankcase gases to the intake manifold, from where they enter the combustion chamber for afterburning.
Fuel tank ventilation system (pic. 5.28) directs the fuel tank vapors to the adsorber, which is purged with atmospheric air, and gasoline vapors enter the inlet pipeline for afterburning.