Fuel Supply System; Intake Air System; Catalytic Converter System; Throttle Body - Honda S2000 Service Manual

Fuel Supply System
Fuel Cut-off Control
During deceleration with the throttle valve closed,
current to the injectors is cut off to improve fuel
economy at speeds over 1,050 rpm
Fuel cut-off action also occurs when engine speed
exceeds 9,000 rpm, regardless of the position of the
throttle valve, to protect the engine from over-rewing.
Fuel Pump Control
When the jgnition is turned ON (ll), the ECM grounds
the PGM-Fl main relay which feeds current to the fuel
pump for 2 seconds to pressurize the fuel system. With
t h e e n g i n e r u n n i n g , t h e E C M g r o u n d s t h e P G M - F l m a i n
relay and feeds current to the fuel pump. When the
e n g i n e i s n o t r u n n i n g a n d t h e i g n i t i o n i s O N ( l l ) , t h e
ECM cuts ground to the PGM-FI main relay which cuts
current to the fuel pump.
PGM.FI Main Relay
The PGM-Fl relay contains two separate relays. One is
energized whenever the ignition is on which supplies
battery vollage to the ECM, power to the injectors, and
power for the second relay. The second relay is
energized to supply power to the fuel pump for 2
seconds when the ignition switch is ON (ll), and when
t h e e n g i n e i s r u n n i n g .
Intake Air System
Refer to the System Diagram to see the functional
layout ofthe system.
Throttle Body
The throttle body is a single-barrel side draft type. The
lower portion of the throttle valve is heated by engine
coolant from the cylinder head.
Catalytic Converter System
TWC {Three.Way Catalytic Converterl
The TWC converts hydrocarbons (HC), carbon
monoxide (CO), and oxides of nitrogen {NOx) in the
exhaust gas to carbon dioxide (CO2). nitrogen (N2), and
water vapor.
THREE WAY
CATALYSTS
FRONT OF
VEHICLE
(cont'd)
11-25