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45
Engine Management
Pump/injector solenoid valve monitoring
The Diesel Direct Fuel Injection Engine
Control Module J248 monitors the electrical
current that actuates the solenoid valves at
the pump/injectors.
This provides feedback to the Diesel
Direct Fuel Injection Engine Control Module
J248 of the actual point in time when
injection begins.
The Diesel Direct Fuel Injection Engine
Control Module J248 uses this feedback to
regulate the beginning of injection periods
(BIP) during subsequent combustion
cycles and to detect malfunctions of the
pump/injector solenoid valves.
Start of injection is initiated when the
pump/injector solenoid valve is actuated.
Actuating current applied to a pump/injector
solenoid valve creates a magnetic field.
As the applied current intensity increases,
the valve closes; the magnetic coil presses
the solenoid valve needle into its valve
seat. This closes off the path from the
fuel supply line to the pump/injector
high-pressure chamber and the injection
period begins.
As the solenoid valve needle contacts its
valve seat, the distinctive signature of an
alternately dropping and rising current flow
is detected by the Diesel Direct Fuel
Injection Engine Control Module J248. This
point is called the beginning of injection
period (BIP). It indicates the complete
closure of the pump/injector solenoid valve
and the starting point of fuel delivery.
“Start of injection” is the point
in time when the actuating
current to the pump/injector
solenoid valve is initiated.
”Beginning of injection
period (BIP)”
is the point in time
when the solenoid valve needle
contacts the valve seat.
With the solenoid valve closed, a holding
current is maintained at a constant level by
the Diesel Direct Fuel Injection Engine
Control Module J248 to keep it closed. Once
the required time period for fuel delivery has
elapsed, the actuating current is switched
off and the solenoid valve opens.
SSP209/097
Current Pattern - Pump/Injector Solenoid Valve
Beginning of
Injection Period
(BIP) (Valve
Closes)
Time
Solenoid V
alve Actuating
Current Intensity
End of
Valve
Actuation
Start of
Valve
Actuation
(Start of
Injection)
Pickup
Current
Control
Limit
Holding
Current