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EC-990
[YD (WITH EURO-OBD)]
ENGINE CONTROL SYSTEM
When the ECM receives a start signal from the ignition switch, the
ECM adapts the fuel injection system for the start control. The
amount of fuel injected at engine starting is a preset program value
in the ECM. The program is determined by the engine speed, engine
coolant temperature and fuel rail pressure.
For better startability under cool engine conditions, the lower the
coolant temperature becomes, the greater the amount of fuel
injected. The ECM ends the start control when the engine speed
reaches the specific value, and shifts the control to the normal or idle
control.
IDLE CONTROL
Input/Output Signal Chart
*: The input signal is sent to the ECM through CAN communication line.
When the ECM determines that the engine speed is at idle, the fuel injection system is adapted for the idle
control. The ECM regulates the amount of fuel injected corresponding to changes in load applied to the engine
to keep engine speed constant. The ECM also provides the system with a fast idle control in response to the
engine coolant temperature signal.
NORMAL CONTROL
Input/Output Signal Chart
The amount of fuel injected under normal driving conditions is deter-
mined according to sensor signals. The crankshaft position sensor
detects engine speed, the accelerator pedal position sensor detects
accelerator pedal position and fuel rail pressure sensor detects fuel
rail pressure. These sensors send signals to the ECM.
The fuel injection data, predetermined by correlation between vari-
ous engine speeds, accelerator pedal positions and fuel rail pres-
sure are stored in the ECM memory, forming a map. The ECM
determines the optimal amount of fuel to be injected using the sen-
sor signals in comparison with the map.
MAXIMUM AMOUNT CONTROL
Input/Output Signal Chart
SEF648S
Sensor Input Signal to ECM ECM Function Actuator
Engine coolant temperature sensor Engine coolant temperature
Fuel injection
control (Idle
control)
Fuel injector
Fuel pump
Crankshaft position sensor Engine speed
Battery Battery voltage
Accelerator pedal position sensor Accelerator pedal position
Fuel rail pressure sensor Fuel rail pressure
Vehicle speed sensor Vehicle speed*
Air conditioner switch Air conditioner signal*
Sensor Input Signal to ECM ECM Function Actuator
Crankshaft position sensor Engine speed
Fuel injection
control (Nor-
mal control)
Fuel injector
Fuel pump
Accelerator pedal position sensor Accelerator position
Fuel rail pressure sensor Fuel rail pressure
SEF649S
Sensor Input Signal to ECM ECM Function Actuator
Mass air flow sensor Amount of intake air
Fuel injection
control (Maxi-
mum amount
control)
Fuel Injector
Engine coolant temperature sensor Engine coolant temperature
Crankshaft position sensor Engine speed
Accelerator pedal position sensor Accelerator pedal position
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