Fuel Injection (Fuel System)
CONTROL SYSTEM
FU-32
E: IDLE AIR CONTROL
! The ECM activates the idle air control solenoid valve to control the bypass air flowing through
the bypass passage in the throttle body depending on signals from the crankshaft position sensor,
engine coolant temperature sensor, pressure sensor and A/C switch so that the proper idle speed
for each engine load is achieved.
! The idle air control solenoid valve uses a duty-ratio-controlled solenoid which can continuously
vary the opening area of the rotary valve. As the ECM increases the duty ratio, opening of the ro-
tary valve increases so that the bypass air flow increases, and the engine idling speed becomes
higher as a result.
! The bypass air control is necessary for:
! Increasing idling speed when the air conditioning system and/or electrical loads are turned
on.
! Increasing idling speed during early stage of warm up period.
! Obtaining dashpot function when the throttle valve is quickly closed.
! Prevention of engine speed variation during idling.
F: FUEL PUMP CONTROL
Using the signal from the crankshaft position sensor, the ECM controls operation of the fuel pump
by turning its relay ON or OFF. To improve safety, the fuel pump is stopped if the engine stalls with
the ignition switch ON.
Ignition switch ON Fuel pump relay Fuel pump
A certain period of time after ignition switch is turned ON ON Operates
While cranking the engine ON Operates
While engine is operating ON Operates
When engine stops OFF Does not operate
B2H3450C
W2290GE_03_FU-.fm 32 ページ ２００１年４月１１日 水曜日 午前９時３６分
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