User Manual

RENR9968-02 7
Systems Operation Section
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Illustrati
on 3
Front view
(9) Primary engine speed/timing sensor
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Illustration 4
Sectio
nA-A
(10) F uel pressure sensor
(11) Fuel te mperature sensor
The electronic control system is integrally designed
into the engine’s fuel system and the engine’s air
inlet and exhaust system in order to electronically
control the fuel delivery. The e lectronic control system
provides better timing control and fuel air ratio control
in comparison t o conventio nal mechanical eng ines.
Injection timing is achieved by the precise co ntrol
of the fuel injectors. Engine speed is controlled
by adjusting the injection duration. The Electronic
Control Module (ECM) energizes the unit injector
solenoids in order to start the injection of fuel. Also ,
the ECM de-energizes the unit injector solenoids in
order to stop the injection of fuel.
Refer to Systems Operation/Testing And Ad justing,
“Fuel System” for a complete explanation of the fuel
injection process .
The engine uses the following three types of
electronic components:
•
Input component
•
Control component
•
Output component
An input component is one that sends an electrical
signal to the ECM. The signal that is sent varies in
either of the following way s :
•
Voltage
•
Frequency
•
Pulse width
The variation of the signal is in response to a change
in some specific system of the engine. Some specific
examples of an input component are the engine
speed-timing sensors, and the coolant temperature
sensor. The ECM interprets the signal from the
input component as information about the condition,
environment, or operation of the engine.
An ECM receives the input signals from the input
components. Electronic circuits inside the control
component evaluate the s ignals from the input
components. These electronic circuits a lso supply
electrical energy to the output components of the
system. The electrical e ne rgy that is supplied to
the output components is based on predetermined
combinations of input signal values.
An output component is one that is operated by a
control module. The output component receives
electrical energy from the control group. The output
component uses electrical energy to make an
adjustment in one of the engine’s systems. An output
component may also provide information to the
operator.