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The burning of gasoline in your
vehicle's engine produces several by-
products. Some of these are carbon
monoxide (CO), oxides of nitrogen
(NOx), and hydrocarbons (HC).
Gasoline evaporating from the tank
also produces hydrocarbons.
Controlling the production of NOx,
CO, and HC is important to the
environment. Under certain
conditions of sunlight and climate,
NOx and HC react to form
photochemical ‘‘smog.’’ Carbon
monoxide does not contribute to
smog creation, but it is a poisonous
gas.
The Clean Air Act
The United States Clean Air Act sets
standards for automobile emissions. It
also requires that automobile
manufacturers explain to owners how
their emissions controls work and
what to do to maintain them. This
section summarizes how the
emissions controls work.
Crankcase Emissions Control
System
Your vehicle has a positive crankcase
ventilation system. This keeps gasses
that build up in the engine's crankcase
from going into the atmosphere. The
positive crankcase ventilation valve
routes them from the crankcase back
to the intake manifold. They are then
drawn into the engine and burned.
Evaporative Emissions Control
System
As gasoline evaporates in the fuel
tank, an evaporative emissions
control canister filled with charcoal
adsorbs the vapor. It is stored in this
canister while the engine is off. After
the engine is started and warmed up,
the vapor is drawn into the engine
and burned during driving.
Onboard Refueling Vapor
Recovery
The onboard refueling vapor
recovery (ORVR) system captures
the fuel vapors during refueling. The
vapors are adsorbed in a canister
filled with activated carbon. While
driving, the fuel vapors are drawn
into the engine and burned off.
Emissions Controls
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10/08/06 08:34:41 11 ELEMENT MMC North America Owner's Man 50 31SCV680 enu
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