5. FUEL INJECTION SYSTEM
MOVIE S 150i
Keihin System Working Principle
1) After Key-On, Fuel Pump will run for 5-10 seconds; if the user is not
starting engine after the 5-10 seconds, ECU will turn off fuel pump relay to
save electricity consumption. Thereafter, ECU will read the following 6
signal input value:
(1) Crank Position Sensor: calculate engine RPM with the cycle time of
crank
(2) Throttle Position Sensor: Detecting open level of throttle
(3) Engine Temp. Sensor: Detect the temp at cylinder head of engine
(4) Intake Temp and Pressure Sensor (T-MAO Sensor): Located at the
intake air manifold for detecting the pressure and temperature of intake
air
(5) Battery output voltage
(6) Oxygen Sensor: Located at Exhaust Pipe A for detecting the A/F ratio
of waste gas and feed back to ECU for computing and controlling
injecting quantity and maintain theoretical mixing ratio.
2) Start Engine
3) ECU will first determine the operating condition of engine by the engine
RPM and Throttle Open level (Stall / Cranking / Idle/ Run/ ORC) (ORC:
Over Run Cut)
4) ECU calculate the control values required by the following 3 sets through
the set values of MAP based on stable or temporary conditions in
accordance with Engine Operating Status and the above 6 sets of sensor
value.
(1) Injection Timing (BTDC) and Fueling per Cycle (F.P.C.)
(2) BTDC timing for opening bypass valve at idle and duration of opening
(3) Ignition angle timing and magnetizing time (% Max)
5) Transforming the above duration of opening and timing into the
corresponding number of teeth of flywheel.
6) Control fuel injector, Air Bypassing valve and ignition coil based on
corresponding teeth.
Repeat (3) through (6) till Key Off.
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