CH 16
Which type of EUIs were used by most OEMs before 2007?
Two-terminal
How many actuators are used in a four-terminal EUI?
Two
What device on a typical CR system prevents constant fueling of a cylinder if one of the EHIs sticks in the open position?
Flow limiter.
The ending of injection pump effective stroke is known as:
port opening
The device used to rotate the injection pump plungers in unison is known as a:
rack
How many high pressure pump elements are used on a Bosch radial piston pump fueling a 6-cylinder engine with a CR (common rail) fuel system?
Three
When EUIs are used after 2007 on highway engines, which type of injector is required?
Four-terminal EUI
What force is used to hold a CR EHI nozzle valve in its closed and seated position when the engine is running?
Combined hydraulic and spring force.
Static timing can also be referred to as
port closure timing
A port-helix metering injection pump managing a direct-injected diesel engine would typically be port closure timed to what position on the engine?
20 degrees BTDC
Which of the following best describes the type of injectors used with CR fuel systems?
Electrohydraulic injectors (EHIs)
Which of the following values would represent a typical NOP for a four-terminal EUI equipped with an EHI
Soft value NOPs controlled by ECM
The beginning of the injection pump effective stroke is known as:
port closure
Charging pressures in a port-helix metering injection pump are created by a(n):
supply pump
Which type of cam geometry is used to actuate the high-pressure pump elements in most inline port-helix metering injection pumps?
Symmetrical of mostly inner base circle design
Which of the following best describes the means by which the ECM drivers control the actuation of CR EHIs?
Pulse width modulation (PWM).
Which of the following is the key component used to signal actual rail pressure to the ECM?
Rail pressure sensor
What component replaces the governor housing at the rear of a port-helix metering injection pump if it is managed by a computer?
Rack actuator housing
360 degrees of pump rotation is equal to how many degrees of engine rotation?
720 degrees
What is the function of the flutes machined into a typical delivery valve core?
Guide the valve in the body
Technician A says that when a four-terminal EUI is injecting fuel into the engine cylinder the SV actuator must energized? Technician B says that for fuel injection to take place in a four-terminal EUI, the NCV actuator must be energized. Who is correct?
Both A and B
Which of the following are advantages of multipulse injection cycles?
Better fuel economy, Lower noise levels, Lower cold start emissions
What is the function of the retraction collar/piston on the delivery valve core?
Permit the valve to seal before it seats
An electronically managed port-helix metering injection pump has ECM-managed variable timing with a 20-degree window statically timed at 8 degrees BTDC. What is the timing window within which the ECM can select the port closure event?
28 degrees BTDC to 8 degrees BTDC
How many fuel pump elements are required on a Bosch 8500 injection pump fueling an inline six-cylinder engine?
Six