SELVA MARINE Blue Whale 250 EFI, Service Manual

Page: 34 / 377

GEN
INFO
General information
1-29
6P23H11
Variable camshaft timing control system
In the Blue Wlale 250 engine, the opening and closing timing of the intake valves is controlled.
The ECM operates the oil control valve according to the engine speed and the electronic throttle
valve opening angle and controls the optimum opening and closing timing of the intake valves. Max-
imum output is achieved by increasing the volumetric efficiency of the combustion chambers under
various engine operating conditions.
Variable camshaft timing control
Variable camshaft timing control diagram
The ECM determines the intake valve opening and closing timing suitable for the operating condi-
tions according to the engine speed, electronic throttle valve opening angle, and engine tempera-
ture. In addition, the exhaust and intake cam position sensors detect the actual advance position
and perform feedback control of the oil control valve to reach the target advance position.
The ECM sends a signal to the oil control valve to switch the oil passage to send engine oil to the
advance chamber or retard chamber in the rotor vane housing. According to the engine oil pressure
in the respective chamber, the rotor vane operates to advance or retard the camshaft that is con-
nected to the rotor vane.
Description Control Engine condition
Variable camshaft
timing • Sets the advance target angle according
to the engine speed and electronic throttle
valve opening.
• Detects the exhaust and intake camshaft
positions, operates the oil control valve to
reach the advance target angle, and con-
trols the optimum opening and closing tim-
ing of the intake valves.
At mid-speed range, oper-
ates to the advance angle,
and at engine idle speed
and the fully open range,
operates to the retard
angle.
S6P21113
(PORT EX) (PORT IN)
Rotor vane housing
(STBD IN)
Rotor vane housing
Advance/Retard
direction Advance/Retard
direction
Sensor
signal
Oil control valve
Oil flow
Oil control valve
Drive signal
Advance Retard Retard Advance
Cam Cam
Cam position
sensor
Engine
temperature
sensor
Crank position
sensor
TPS
ECM
Return
Oil filter Oil pump
Oil pan
Return
Cam
Cam position
sensor
Cam position
sensor