Volvo S70 Owner's Manual page 189

1999 S70 & V70
Secondary Air Injection (certain models)
This system adds air to the hot exhaust gases as they are expelled from the engine. This causes a
secondary combustion of residual hydrocarbons and carbon monoxide, resulting in lower emissions
levels in the exhaust gases.
Crankcase ventilation
The engine is provided with positive crankcase ventilation which prevents crankcase gases from being
released into the atmosphere. Instead, the crankcase gases are admitted to the intake manifold and
cylinders.
Evaporative control system
The car is equipped with a gas evaporative control system, which prevents gasoline vapor from being
released into the atmosphere. The system is comprised of an expansion chamber in the fuel tank, a roll-
over valve, a charcoal canister, vapor vent lines, an EVAP valve and on certain models, an Onboard
Refueling Vapor Recovery valve (ORVR). The gasoline vapor is channeled through the rollover valve
and the ORVR (if applicable) via the vent lines into the charcoal canister, where it is stored. When the
engine is started, the gasoline vapor is drawn from the charcoal canister to the engine's air intake system
and into the combustion process.
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Crankcase ventilation