Î
ÎThe 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 f rom the tank
also produces hydrocarbons. Con-
trolling the production of NOx, CO,
and HC is important to the environ-
ment. Under certain conditions of
sunlight and climate, NOx and HC
react to f orm photochemical ‘‘smog.’’
Carbon monoxide does not contri-
bute to smog creation, but it is a
poisonous gas. The United States Clean Air Act
sets standards f or automobile
emissions. It also requires that
automobile manufacturers explain to
owners how their emissions controls
workandwhattodotomaintain
them. This section summarizes how
the emissions controls work.
In Canada, Honda vehicles comply
with the Canadian emission
requirements, as specif ied in an
agreement with Environment
Canada, at the time they are
manuf actured.
Your vehicle has a positive
crankcase ventilation system. This
keeps gasses that build up in the
engine’s crankcase f rom going into
the atmosphere. The positive
crankcase ventilation valve routes
them from the crankcase back to the intake manif old. They are then
drawn into the engine and burned.
The onboard ref ueling vapor
recovery (ORVR) system captures
the f uel vapors during ref ueling. The
vapors are adsorbed in a canister
f illed with activated carbon. While
driving, the f uel vapors are drawn
into the engine and burned of f . As gasoline evaporates in the f uel
tank, an evaporative emissions
control canister f illed with charcoal
adsorbs the vapor. It is stored in this
canister while the engine is of f . Af ter
the engine is started and warmed up,
the vapor is drawn into the engine
and burned during driving.
The Clean Air Act
Crankcase Emissions Control
System
Onboard Ref ueling Vapor
Recovery Evaporative Emissions Control
System
Emissions Cont rols
Technical Inf ormation
287
The emissions control systems are
designed and certif ied to work to-
gether in reducing emissions to
levels that comply with the Clean Air
Act. To make sure the emissions
remain low, you should use only new
Honda replacement parts or their
equivalent f or repairs. Using lower
qualitypartsmayincreasethe
emissions f rom your vehicle.
The emissions control systems are
covered by warranties separate from
the rest of your vehicle. Read your
warranty manual for more informa-
tion.
The exhaust emissions controls
include f our systems: PGM-FI,
ignition timing control, exhaust gas
recirculation, and three way catalytic
converter. These f our systems work
together to control the engine’s
combustion and minimize the
amount of HC, CO, and NOx that
come out the tailpipe. The exhaust
emissions control systems are
separate f rom the crankcase and
evaporative emissions control
systems.
The PGM-FI system uses sequential
multiport f uel injection. It has three
subsystems: air intake, engine
control, and f uel control. The
powertrain control module (PCM) in
automatic transmission vehicles or
the engine control module (ECM) in
manual transmission vehicles uses
various sensors to determine how
much air is going into the engine. It then controls how much f uel to inject
under all operating conditions.
This system constantly adjusts the
ignition timing, reducing the amount
of HC, CO, and NOx produced.
The exhaust gas recirculation (EGR)
system takes some of the exhaust
gas and routes it back into the intake
manif old. Adding exhaust gas to the
air/f uel mixture reduces the amount
of NOx produced when the f uel is
burned.
The three way catalytic converter is
in the exhaust system. Through
chemical reactions, it converts HC,
CO, and NOx in the engine’s exhaust
to carbon dioxide (CO ), nitrogen
(N ), and water vapor.
2
2
Exhaust Emissions Controls Replacement Parts
Emissions Cont rols
PGM-FI SystemIgnit ion T iming Cont rol Syst em
Exhaust Gas Recirculat ion (EGR)Syst em
Three Way Catalytic Converter
288
