Honda Accord 2008 Manual page 355

07/11/02 09:00:44 61TA0000_110_0036
Fuel and Emissions Systems
System Description (cont'd)
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 to prevent icing of the
throttle plate.
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Idle Control System
When the engine is cold, the A/C compressor is on, the
transmission is in gear, the brake pedal is pressed, the
power steering load is high, or the alternator is
charging, the ECM/PCM controls current to the throttle
actuator to maintain the correct idle speed.
Brake Pedal Position Switch
The brake pedal position switch signals the ECM/PCM
when the brake pedal is pressed.
Power Steering Pressure (PSP) Switch
The PSP switch signals the ECM/PCM when the power
steering load is high.
11-36
THROTTLE VALVE
THROTTLE POSITION
(TP) SENSOR and
THROTTLE ACTUATOR
Fuel Supply System
Fuel Cutoff Control
During deceleration with the throttle valve closed,
current to the injectors is cut off to improve fuel
economy at engine speeds over 850 rpm (A/T) or
1,000 rpm (M/T). Fuel cutoff also occurs when the
engine speed exceeds 7,000 rpm (LX) or 7,300 rpm (EX),
regardless of the position of the throttle valve, to
protect the engine from over-revving. When the vehicle
is stopped, the ECM/PCM cuts the fuel at engine speeds
over 5,000 rpm (A/T), 7,000 rpm (LX M/T), or 7,100 rpm
(EX M/T). The engine speed of fuel cut is lower on a
cold engine.
Fuel Pump Control
When the ignition is turned on, the ECM/PCM grounds
PGM-FI main relay 2 (FUEL PUMP) which feeds current
to the fuel pump for 2 seconds to pressurize the fuel
system. With the engine running, the ECM/PCM
grounds PGM-FI main relay 2 (FUEL PUMP) and feeds
current to the fuel pump. When the engine is not
running and the ignition is on, the ECM/PCM cuts
ground to PGM-FI main relay 2 (FUEL PUMP) which cuts
current to the fuel pump.
PGM-FI Main Relay 1 and 2
PGM-FI main relay 1 is energized whenever the ignition
switch is ON (II) to supply battery voltage to the ECM/
PCM, power to the injectors, and power for PGM-FI
main relay 2 (FUEL PUMP). PGM-FI main relay 2 (FUEL
PUMP) is energized to supply power to the fuel pump
for 2 seconds when the ignition switch is turned to
ON (II), and when the engine is cranking or running.