Doosan D20S-7 - Electronic Controlled Spark-Ignition Engines (GCT K25 Engine)

Operation Section
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Electronic Controlled Spark-Ignition Engines
(GCT K25 Engine)
Adopts Electronic Concentrated engine Control System (ECCS). Fuel injection control, ignition timing control, idle
speed control, and electronically controlled governor control etc. are all performed by a single control unit.
Adopts electric throttle control actuator system to control electronically controlled governor.
Adopts Hall IC type crankshaft position sensor (POS) and camshaft position sensor (PHASE).
Items Description
Electric throttle control actuator  Adopts electronic throttle control actuator with integrated throttle
control motor to adjust throttle valve opening optimally according
to driving conditions or to improve safety and operability by
electronically controlled governor.
Fuel injection control  With fuel injection control, air-fuel ratio is optimized to improve
exhaust performance and response.
 Using feedback control through learning of air-fuel ratio
compensation, the system corrects the ratio during transitional
conditions, such as sudden sharp changes in the ratio, in order to
improve drivability.
Ignition timing control  Uses Hall IC crankshaft position sensor (POS) and camshaft
position sensor (PHASE) to perform controls so that optimum
ignition timing is obtained for every operating condition. Optimum
ignition timing setup according to each fuel is also enabled at the
time of a combined use formula.
 Adopts electronic distribution system (NDIS) in which each
cylinder is equipped with an ignition coil incorporating a power
transistor for better ignition performance.
Idle speed control  Adopts electronic throttle control actuator that continuously
regulates intake air amount required for idling.
Governor speed control  Performs maximum regulation of engine speed for oil pressure
pump protection by engine speed signal.
Maximum speed regulation
control
 Performs maximum speed regulation by vehicle speed sensor
signal. Also, performs variable control of maximum speed by
changeover switch.
Idling area torque up control  Performs torque up control in idling area by engine speed signal in
order to also enable cargo work at idling.
Overheat prevention control  Reduces engine heat generation by reducing maximum engine
speed and regulating maximum throttle opening when engine
coolant temperature reaches approximately 110°C (230°F).
 Prevents resulting in engine breakage by overheat by performing
fuel cut at 1,000 rpm or more when engine coolant temperature
reaches approximately 135°C (275°F).
Power/ECO mode control  Changes throttle opening characteristic of throttle position by
power/ECO mode control switch, and then minute operation of
engine speed is enabled. (Option setting)
Fuel pump control (gasoline)  Turns fuel pump relay ON/OFF depending on engine speed
signal.
LPG interception valve control  Turns interception valve relay ON/OFF depending on engine
speed signal and fuel pressure sensor signal.
Fail-safe function  Ensures vehicle's safe operation and enables vehicle to be driven
in an emergency when any of the major system components
(mass air flow sensor, engine coolant temperature sensor, etc.)
have malfunctioned.
Diagnostic system  Adopts self-diagnosis system for easier trouble diagnosis .