Exam 12: Heui Injection Systems

Two control signals from the ECM are supplied to the FICM (fuel injection control module): the fuel-delivery control signal (FDCS) and the:

While diagnosing the cause of a hard start/prolonged cranking complaint, Technician A says that the high-pressure oil between the high-pressure pump and the injectors should stay pressurized for days. Technician B says the oil pressure to the injectors should quickly drop to zero when the engine is shut off. Who is correct?

Which of the following components multiplies oil pressure inside a HEUI injector?

During which part of the HEUI (hydraulically actuated electronic unit injection) injector injection cycle does the lower seat of the poppet valve block high-pressure oil from entering the injector?

Oil thickened by excessive soot loading will interfere with injector control valves operating properly, particularly in:

When the spool valve opens, high-pressure oil is directed to the top of the _____ and then injection begins.

What level of voltage do HEUI (hydraulically actuated electronic unit injection) A and B injectors require?

Which module stores information such as engine firing order and operating and diagnostic software instructions?

What is the measuring unit for the electrical signal to the ICPR of a HEUI fuel system?

Reservoirs with a capacity of approximately ________ are incorporated into high-pressure pumps or cavities in the engine.

Which of the following forces do Gen II HEUI injectors use to physically move the spool valve in the injector control valve mechanism when it opens or closes?

Technician A says the measuring unit for the electrical signal to the injection control pressure regulator of a HEUI fuel system is reported as a percentage of duty cycle (%) on a scanner display of engine parameters. Technician B says the PWM signal is reported as time (in milliseconds). Who is correct?

Two technicians are describing HEUI HIB-300 injector operation. Technician A says that lifting the poppet valve opens a passageway, allowing pressurized oil above the nozzle valve to drain to a low-pressure oil return. Technician B says that a spool valve moves from side to side controlled only by magnetic forces. Who is right?

While considering ways to increase engine power output, Technician A says that using a special injection control pressure (ICP) sensor, which reports oil pressure as lower than the actual pressure, is an effective shortcut. Technician B says that using the modified ICP sensor signal will result in less fuel being injected. Who is correct?

What is used in the wiring harness to indicate to the ECM the viscosity of oil used?

Technician A says acoustic wave attenuation (AWA) fittings in the oil manifold of some Gen II HEUI engines reduce irregular combustion noise. Technician B says split-shot injection reduces combustion noise. Who is correct?

Technician A says that during an oil change, oil can be drained from the accumulator or reservoir of a HEUI (hydraulically actuated electronic unit injection) system. Technician B says that reservoirs with a capacity of approximately 0.26 gallon (1 liter) are incorporated into high-pressure pumps or cavities in the HEUI engine. Who is right?

Two technicians are describing HEUI HIB-300 injector operation. Technician A says that fuel travels to the cavity above the amplifier piston while pressurized oil is applied to two sides of the poppet valve and to the top of the nozzle valve, holding it closed. Technician B says that when the poppet valve is energized, the valve lifts, closing off the high-pressure oil passageway and applying pressure to the nozzle valve. Who is right?

Which of the following minimizes a rhythmic cackling noise at idle caused by pressure waves from the high-pressure pump synchronizing with injection events?

Which part of the Gen II injector event energizes the open coil, moving the spool valve to the open position?