Honda 2009 Pilot Owner's Manual page 558

Emissions Controls
Exhaust Emissions Controls
The exhaust emissions controls
include four systems: PGM-FI,
ignition timing control, exhaust gas
recirculation, and three way catalytic
converter. These four 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 from the crankcase and
evaporative emissions control
systems.
PGM-FI System
The PGM-FI system uses sequential
multiport fuel injection.
It has three subsystems: air intake,
engine control, and fuel control. The
powertrain control module (PCM)
uses various sensors to determine
how much air is going into the
engine. It then controls how much
fuel to inject under all operating
conditions.
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Ignition Timing Control System
This system constantly adjusts the
ignition timing, reducing the amount
of HC, CO, and NOx produced.
Exhaust Gas Recirculation (EGR)
System
The exhaust gas recirculation (EGR)
system takes some of the exhaust
gas and routes it back into the intake
manifold. Adding exhaust gas to the
air/fuel mixture reduces the amount
of NOx produced when the fuel is
burned.
Three Way Catalytic Converter
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
2
(N ), and water vapor.
2
Replacement Parts
The emissions control systems are
designed and certified 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 for repairs. Using lower
quality parts may increase the
emissions from 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.