Question 1

While bench testing a multi-orifice injector nozzle, it rapidly pulses (chatter)  as NOP is achieved. Technician A says that the nozzle seat is defective and should be replaced. Technician B says that nozzle chatter usually occurs only during bench testing. Who is right?

Accepted Answer

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

Question 2

What is the geometric relationship between the sectional area of the nozzle seat, and that of the nozzle pressure chamber known as?

Accepted Answer

A)   nozzle differential ratio
B)   seat to shank ratio
C)   NOP to line pressure ratio
D)   peak pressure to NOP ratio

Question 3

When considering EHI operation in a standard CR system while the engine is running but the actuator is not energized which of the following is true?

Accepted Answer

A)   rail pressure is at nozzle needle seat
B)   rail pressure is present in the upper pressure field
C)   the upper and lower pressure fields are at the same pressure
D)   all of the above

Question 4

When multi-orifice nozzles are used in hydromechanical diesel engines, what would be a typical NOP value?

Accepted Answer

A)   5000 psi
B)   3000 psi
C)   2000 psi
D)   800 psi

Question 5

As pressure increases in the injection circuit, what happens to the emitted droplet sizing?

Accepted Answer

A)   increases in size
B)   decreases in size
C)   becomes less aerated
D)   becomes more aerated

Question 6

What is required to test the NOP of a hydraulic injector?

Accepted Answer

A)   OEM software
B)   bench test fixture
C)   ultrasonic bath
D)   pressure pulse, line transducer

Question 7

Technician A says that high pressure fuel can exit an injector nozzle at faster than the speed of sound. Technician B says that the most OEMs recommend electrohydraulic injectors (EHIs)  to be field serviced using standard shop tools. Who is correct?

Accepted Answer

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

Question 8

A hydraulic injector nozzle that uses a sacless design is known as:

Accepted Answer

A)   pencil injector
B)   low spring injector
C)   valve closes orifice (VCO)  injector
D)   high spring injector

Question 9

Technician A says that multi-orifice hydraulic injectors have hard value NOPs. Technician B says that NOPs in electrohydraulic injectors (EHIs)  have variable NOPs that are controlled by the ECM. Who is correct?

Accepted Answer

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

Question 10

What determines the soft opening and closing values of EHIs in any given moment of engine operation?

Accepted Answer

A)   rail pressure
B)   electrical pressure at injector driver
C)   ECM
D)   engine rpm

Question 11

What type of injector nozzles are used with today's direct injected engines?

Accepted Answer

A)   poppet and pintle
B)   pencil
C)   multi-orifice and electrohydraulic
D)   mechanical and pneumatic

Question 12

Which of the following is another way of saying injector bench test fixture?

Accepted Answer

A)   pop tester
B)   ultrasonic bath
C)   nozzle orifice reamer
D)   lapping block

Question 13

When a multi-orifice injector nozzle is closed, what seals the nozzle assembly from the engine cylinder?

Accepted Answer

A)   nozzle sac
B)   nozzle shank
C)   nozzle line nut
D)   nozzle valve seat

Question 14

Which of the following tools can be used to pull a flanged hydraulic injector nozzle from a cylinder head?

Accepted Answer

A)   pry bar
B)   injector heel bar
C)   injector sleeve broach
D)   screwdriver

Question 15

Identify the nozzle capable of soft opening pressures?

Accepted Answer

A)   electrohydraulic (EHI) 
B)   multi-orifii in EUIs
C)   pintle
D)   pencil

Question 16

If a 4-stroke cycle diesel engine is run at 2000 rpm, how much real time is required for a single revolution of the engine?

Accepted Answer

A)   5 milliseconds
B)   15 milliseconds
C)   30 milliseconds
D)   60 milliseconds

Question 17

?Technician A says that EHIs are ECM switched to open and close. Technician B says that EHIs are opened when pressure in the CR rises to the nozzle opening pressure. Who is correct?

Accepted Answer

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

Question 18

What is a typical NOP value of the multi-orifice nozzle used in an EUI (electronic unit injector) ?

Accepted Answer

A)   800 psi
B)   2000 psi
C)   3000 psi
D)   5000 psi

Question 19

When attempting to remove a seized injector spacer washer, which of the following tools would be recommended?

Accepted Answer

A)   taper reamer
B)   heel end of an injector heel bar
C)   tapered end of an injector heel bar
D)   hammer and punch

Question 20

Which type of multi-orifice injector nozzle sometimes uses an accumulator in place of a leakoff circuit?

Accepted Answer

A)   pencil injectors
B)   valve closes orifice (VCO) 
C)   high spring injectors
D)   low spring injectors

Exam 21: Injector Nozzles

Technician A says that high pressure fuel can exit an injector nozzle at faster than the speed of sound. Technician B says that the most OEMs recommend electrohydraulic injectors (EHIs) to be field serviced using standard shop tools. Who is correct?

Correct AnswerverifiedShow Answer

Technician A says that multi-orifice hydraulic injectors have hard value NOPs. Technician B says that NOPs in electrohydraulic injectors (EHIs) have variable NOPs that are controlled by the ECM. Who is correct?

Correct AnswerverifiedShow Answer

What is required to test the NOP of a hydraulic injector?

Correct AnswerverifiedShow Answer

While bench testing a multi-orifice injector nozzle, it rapidly pulses (chatter) as NOP is achieved. Technician A says that the nozzle seat is defective and should be replaced. Technician B says that nozzle chatter usually occurs only during bench testing. Who is right?

Correct AnswerverifiedShow Answer

Which type of multi-orifice injector nozzle sometimes uses an accumulator in place of a leakoff circuit?

Correct AnswerverifiedShow Answer

When multi-orifice nozzles are used in hydromechanical diesel engines, what would be a typical NOP value?

Correct AnswerverifiedShow Answer

When considering EHI operation in a standard CR system while the engine is running but the actuator is not energized which of the following is true?

Correct AnswerverifiedShow Answer

What is the geometric relationship between the sectional area of the nozzle seat, and that of the nozzle pressure chamber known as?

Correct AnswerverifiedShow Answer

?Technician A says that EHIs are ECM switched to open and close. Technician B says that EHIs are opened when pressure in the CR rises to the nozzle opening pressure. Who is correct?

Correct AnswerverifiedShow Answer

If a 4-stroke cycle diesel engine is run at 2000 rpm, how much real time is required for a single revolution of the engine?

Correct AnswerverifiedShow Answer

Which of the following is another way of saying injector bench test fixture?

Correct AnswerverifiedShow Answer

When attempting to remove a seized injector spacer washer, which of the following tools would be recommended?

Correct AnswerverifiedShow Answer

Which of the following tools can be used to pull a flanged hydraulic injector nozzle from a cylinder head?

Correct AnswerverifiedShow Answer

What determines the soft opening and closing values of EHIs in any given moment of engine operation?

Correct AnswerverifiedShow Answer

A hydraulic injector nozzle that uses a sacless design is known as:

Correct AnswerverifiedShow Answer

What type of injector nozzles are used with today's direct injected engines?

Correct AnswerverifiedShow Answer

Identify the nozzle capable of soft opening pressures?

Correct AnswerverifiedShow Answer

When a multi-orifice injector nozzle is closed, what seals the nozzle assembly from the engine cylinder?

Correct AnswerverifiedShow Answer

What is a typical NOP value of the multi-orifice nozzle used in an EUI (electronic unit injector) ?

Correct AnswerverifiedShow Answer

As pressure increases in the injection circuit, what happens to the emitted droplet sizing?

Correct AnswerverifiedShow Answer

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