Honda 1990 Accord Sedan Owner's Manual page 129

Emission Controls (cont'd)
Engine Exhaust Controls
The engine exhaust emission control systems are designed to
control combustion during idle, acceleration, cruise, and decel-
eration. These systems are entirely separate from the
crankcase and evaporative emission control systems describ-
ed previously.
PGM-FI System
The PGM-FI system consists of three independent sub-
systems; Air Intake, Electronic Control and Fuel Control, thus
allowing more accurate control of air/fuel ratios under all
operating conditions. The Electronic Control Unit (ECU)
detects the amount of air drawn into the cylinders and deter-
mines the amount of fuel to be injected to provide the optimum
air/fuel ratio for all engine needs.
Ignition Timing Control System
This system automatically controls the ignition timing to
reduce the amount of HC and NOx.
Catalytic Converter
The catalyst is used to convert hydrocarbons (HC), carbon
monoxide (CO) and oxides of nitrogen (NOx) in the exhaust
gas, to carbon dioxide (CO
Exhaust Gas Recirculation (EGR)
The EGR system is designed to control the formation of oxides
of nitrogen (NOx) caused when fuel mixture burns at high
temperature. It works by recirculating exhaust gas through the
EGR valve and intake manifold into the combustion chambers
where it reduces peak temperature by diluting the air/fuel
mixture.
), dinitrogen (N
2
) and water vapor.
2