Deck 8: Injector Nozzles

Question 1

How is the piezo stack in a EHI linked to the control valve?

A) Directly with a piston.
B) By a fuel-charged hydraulic coupler.
C) By the injector spindle.
D) Using a fuel charged duct.

Answer 1

B

Question 2

What feature is eliminated or reduced in size on valve closes orifice (VCO) nozzles?

A) Pressure chamber.
B) Sac.
C) Lower pressure chamber.
D) Valve control chamber.

Answer 2

B

Question 3

What do most manufacturers specify about their common rail (CR) high pressure lines?

A) They have a pre-determined service life.
B) They can be reinstalled only once.
C) They should never be removed other than in a OEM factory environment.
D) They are single-use components.

Answer 3

D

Question 4

Testing EHIs on a computerized test bench will produce what type of results?

A) An estimate of remaining service life.
B) A detailed evaluation of each sub-component in the EHI.
C) A detailed report of EHI performance over a range of conditions.
D) OK or Not OK.

Question 5

What advantage do piezoelectric actuators offer over solenoid actuators?

A) Faster response and lower power requirements.
B) Much better dependability.
C) Faster response and higher injection pressures.
D) Cheaper to manufacture.

Question 6

What type of fuel injectors are required an almost all post 2007 diesel engines?

A) Electrohydraulic injectors.
B) Hydraulic.
C) Mechanical.
D) Electronic unit injectors.

Question 7

What is the function of the nozzle sac used in hydraulic injectors?

A) Hydraulically balances the fuel charge before injection.
B) Retain a constant supply of fuel close to the injection nozzle.
C) Slightly heat the fuel charge before injection.
D) Hydraulically absorb pressure wave reflections during injector events.

Question 8

When replacing contemporary injectors, what needs to be programmed into the PCM?

A) Injector calibration codes.
B) The injector service bit need to be reset to 0.
C) Which injectors were changed by cylinder number.
D) Nozzle opening pressure values.

Question 9

Technician A states that older hydraulic injectors were calibrated to open and close at a specific hard-value pressure known as nozzle opening pressure (NOP). Technician B states that current injectors have a variable NOP controlled by the PCM. Which technician is correct?

A) Technician A only.
B) Technician B only.
C) Both A and B.
D) Neither A nor B.

Question 10

How does the PCM control the EHI?

A) By sending data directly to the EHI via the databus.
B) Via the injector control unit.
C) Using a digital to analog converter chip.
D) Using a pulse-width modulated (PWM) electrical charge.

Question 11

What is a hydraulic injector test bench fixture commonly referred to as?

A) Nozzle valve tester.
B) Electronic service tool.
C) Pop tester.
D) Ultrasonic bath.

Question 12

What component uses either a solenoid or piezoelectric actuator to operate?

A) Pencil injectors.
B) Common rails.
C) Unit injectors.
D) Electrohydraulic Injectors.

Question 13

What is the key feature of electrohydraulic nozzles?

A) They have fixed opening and closing pressure values.
B) They require very little power to operate.
C) They open and close independently from PCM commands.
D) They do not have fixed opening and closing pressure values.

Question 14

What are the two types of actuator used in electrohydraulic injectors?

A) Mechanical and solidstate.
B) Solenoid and servo.
C) Servo and piezoelectric.
D) Solenoid and piezoelectric.

Question 15

What determines the injectors nozzle opening pressure (NOP) in a hydraulic injector?

A) It is a soft value controlled by the PCM.
B) Injector spring tension.
C) Injector actuators.
D) Fuel pressure.

Question 16

What is the nozzle closing pressure (NOP) equivalent to on a typical hydraulic injector?

A) 10 to 20 percent lower than the NOP.
B) 10 to 20 percent higher than NOP.
C) Equal to NOP.
D) 99.9 percent of the NOP.

Question 17

What is the highest pressure a fuel injection system can produce referred to as?

A) Maximum pressure.
B) Fuel compressibility limit.
C) Peak pressure.
D) Burst pressure.

Question 18

What component defines the exact distance an injector nozzle tip protrudes into the cylinder?

A) Nozzle seat.
B) Cylinder head injector seat.
C) Nozzle spacer.
D) Injector springs.

Question 19

What is the practice of dividing an injection pulse into several injection pulses during a single intake cycle referred to as?

A) Variable-pulse injection.
B) Multi-phase injection.
C) Multi-pulse injection.
D) Delayed-phase injection.

Question 20

Technician A states whenever a electrohydraulic injector is changed-out the PCM needs to be programmed with the new injectors calibration code. Technician B states that if a electrohydraulic injector is moved from on cylinder to another, PCM re-programming is not required. Who is correct?

A) Technician A only.
B) Technician B only.
C) Both A and B.
D) Neither A nor B.