Deck 13: Common Rail Fuel Systems

Question 1

Technician A says that a CR engine can vary the injection pressure, timing, and injection rate shape for each injector. Technician B says that the injection pressure is the same for all injectors in CR engines, and injectors can perform multiple injection events during each combustion cycle. Who is correct?

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

Answer 1

B

Question 2

Technician A says that servo-hydraulic injector actuators use a small amount of control valve movement to control larger, more powerful, and faster-acting hydraulic forces. Technician B says that control valves that use piezoelectric technology are the only actuators capable of servo action. Who is correct?

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

Answer 2

A

Question 3

Technician A says that rate shaping involves changing the quantity of fuel as it is discharged from the injector spray holes. Technician B says that rate shaping requires multiple injection events and a high-pressure fuel system with the ability to vary injection pressure. Who is correct?

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

Answer 3

C

Question 4

Technician A says that cylinder misfires can be detected on CR engines by slightly cracking open the fuel line to each injector when the engine is running. Technician B says that it is important to place a shop towel over the injector when checking for misfires to prevent pressurized fuel from penetrating the skin. Who is correct?

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

Question 5

Consider a hydraulically balanced needle valve used in a first- or second-generation Bosch common rail (CR) injector. How would a drain orifice that is much larger than the inlet orifice affect its functioning?

A)Slower nozzle lift than closing.
B)Faster nozzle opening than closing.
C)Failure of the nozzle valve to lift.
D)Failure of the nozzle valve to close.

Question 6

Consider a non-amplified CR injector. If the injection control valve cannot close properly due to dirt or erosion of the valve seat, what is the most common result?

A)The injector cannot deliver any fuel.
B)The nozzle valve stays seated.
C)The nozzle valve remains open.
D)The flow control valve remains open.

Question 7

Consider a non-amplified CR injector. If the inlet restriction orifice to the pressure control chamber is plugged, what is the most likely to happen?

A)The injector cannot deliver any fuel.
B)The nozzle valve stays seated.
C)The nozzle valve remains open when the engine is running.
D)The flow control valve remains open.

Question 8

Consider a piezoelectric CR injector. What happens to the actuator when current is initially applied to the piezoceramic wafers?

A)The nozzle valve is seated by high-pressure fuel.
B)The crystals expand.
C)The crystals contract.
D)Reaction induction causes a delayed injector response time.

Question 9

Consider a CR3 system with a leaking fuel return line. Which of the following situations is the operator most likely to encounter?

A)A noise in the engine.
B)A cylinder misfire.
C)A no-start condition.
D)Low power.

Question 10

Consider a Bosch CRS2 system. The FCV on a CP-3 pump is open circuited. Which of the following conditions is most likely to be observed?

A)The engine won't start.
B)The engine runs rough.
C)The engine will only idle.
D)Very low engine power.

Question 11

Which Bosch CR system requires certified insulated gloves when working on the system with the ignition key in the On position?

A)CR1.
B)CR2.
C)CR3.
D)CR4.

Question 12

Technician A says that dirt bypassing the filter on some CR systems can cause an injector to stick open and continuously fuel a cylinder. Technician B says that any dirt particles may potentially damage the injector, but they would not allow an injector to full-fuel or cause the engine to run away. Who is correct?

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

Question 13

Technician A says that servo-hydraulic actuators that use electromagnets have better durability than piezoceramic actuators. Technician B says piezoceramic actuators are as durable as, if not more durable than, servo-hydraulic injectors that use electromagnets. Who is correct?

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

Question 14

Technician A says that CRI2 injectors will amplify injection pressure under heavy loads as needed by the engine. Technician B says that injection amplification takes place only in CR3 injectors. Who is correct?

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

Question 15

When performing a back leakage test on a CR engine with CRI2 injectors, excessive fuel flow from the fuel return line was measured from the cylinder head. Which of the following conditions is most likely the cause?

A)A worn-out high-pressure pump.
B)A defective fuel control valve.
C)A leaking quill tube connection.
D)A defective pressure-protection valve.

Question 16

Technician A says that faster-responding piezoelectric injectors are best suited for use in light-duty CR engines. Technician B says that engine speeds of automotive diesel do not require the piezoelectric injector's higher number of injection events. Who is correct?

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

Question 17

What typically happens to the length of the pulse width to the electronic fuel control valve (FCV) valve when fuel leaks from the high-pressure rail?

A)It remains the same.
B)It increases.
C)It decreases.
D)It increases, the suddenly decreases.

Question 18

While two technicians are discussing the purpose of a second electrical control valve, which regulates fuel volume supplied to the inlet of the high-pressure pump, Technician A says the VCV helps reduce fuel consumption. Technician B says the VCV is needed to reduce emissions. Who is correct?

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

Question 19

Which of the following is the most likely cause of excessive fuel return from the cylinder head of a CR engine?

A)Excessive injection pressure.
B)A nozzle valve that is stuck closed.
C)Eroded or pitted ball valve seats.
D)A plugged inlet orifice in one or more injectors.

Question 20

While performing a back leakage test for a second-generation Bosch CR fuel system, the fuel volume was measured to be above specification from the cylinder head. Technician A says the cause could be a leaking quill tube. Technician B says the cause could be one or more injectors with worn-out ball valve seats. Who is correct?

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

Question 21

Current system pressures for heavy-duty CR injection operate as high as:

A)10,000-17,500 psi
B)13,000-25,500 psi
C)30,000-37,500 psi
D)40 000-47 500 psi"

Question 22

Technician A says that modern HPCR (High Pressure Common Rail) fuel pressurization occurs in concert with engine speed. Technician B says that regardless of engine rotational speed and load, HPCR fuel-injection pressure can be electronically controlled to provide the optimal pressure required. Who is right?

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

Question 23

Which of the following fuel systems was developed by Bosch and used by Detroit Diesel's ACR (Amplified Common Rail) system?

A)HADIS (Hydraulically Amplified Diesel-Injection System)"
B)HPCR (High Pressure Common Rail)"
C)HEUI (hydraulically actuated electronic unit injection)
D)EUI (Electronic Unit Injection) system"

Question 24

Which of the following terms refers to a control system that multiplies a small mechanical force or movement into a much greater force or movement?

A)Accumulator"
B)Piston"
C)Piezo
D)Servo"

Question 25

Currently, the fastest production servo-hydraulic CR injector can produce ___ separate injection events during one combustion cycle.

A)4"
B)5"
C)6
D)9"

Question 26

Which of the following is an essential element of rate shaping, which refers to the quantity of fuel injected per degree of crankshaft rotation?

A)Nozzle-valve lift"
B)Fuel rate"
C)Rate curve
D)Injection rate"

Question 27

Two technicians are describing common rail fuel system operation. Technician A says that electronically regulating the pressure in the high-pressure pump permits injection pressures to vary with speed and load conditions. Technician B says that a common rail stores fuel pressurized to match optimal injection pressure for any given engine speed or load condition. Who is right?

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

Question 28

How many main types of CR injectors are there?

A)1"
B)2"
C)3
D)4"

Question 29

Which of the following operations is NOT used by Bosch CR1 and CR2 injectors to inject fuel?

A)Electrical signal is removed from the magnetic solenoid"
B)Servo-hydraulic valve closes"
C)Drain hole from the pressure control chamber opens
D)Rail pressure lifts the nozzle valve"

Question 30

In which of the following Bosch CRS2 injector stages does closing the drain orifice cause fuel pressure to build in the pressure chamber, forcing the control rod against the nozzle valve?

A)Pre-injection"
B)Beginning of injection"
C)End of Injection
D)Post-injection"

Question 31

The CRS1, which had limited use in Europe only, uses a single spring to return the armature to a resting position, whereas the CRS2 uses:

A)two springs"
B)three springs"
C)four springs
D)five springs"

Question 32

Two technicians are discussing piezoceramic injectors. Technician A says that piezo technology involves replacing magnetic solenoids with high speed solenoids. Technician B says that piezoelectric crystals enable much faster injector response than do magnetic actuators. Who is right?

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

Question 33

In which of the 3^rd generation Bosch Piezo CRS3 injector stages is the nozzle valve hydraulically balanced with high-pressure fuel from the rail applied to the top and bottom of the nozzle valve?

A)Beginning of Injection"
B)Pre-injection"
C)End of Injection
D)Resting"

Question 34

Consider a hydraulically balanced needle valve used in a first- or second-generation Bosch common rail (CR) injector. How would a drain orifice that is much larger than the inlet orifice affect its functioning?

A)Slower nozzle lift than closing."
B)Faster nozzle opening than closing."
C)Failure of the nozzle valve to lift.
D)Failure of the nozzle valve to close."

Question 35

What actuator technology is used with the Siemens VDO K16 pump?

A)Servo-hydraulic"
B)Spindle valve (amplified common rail (ACR))"
C)Ball valve
D)Piezoceramic"

Question 36

The Siemens CR injector uses a conventional six-hole nozzle valve that opens inward when the hydraulic balance of the nozzle valve is:

A)higher below the nozzle"
B)lower below the nozzle"
C)the same level as the nozzle
D)higher above the nozzle"

Question 37

Two technicians are explaining the Siemens injector operation. Technician A says that a piezoceramic actuator uses multiple stacked piezo crystal discs that expand longitudinally when electrically energized. Technician B says that fuel pressure in a chamber below the control piston regulates the movement of the control piston. Who is right?

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

Question 38

At which stage of the Siemens injector operation does fuel pressurized by the high-pressure pump enter the fuel rail and is supplied to each injector fitting?

A)Post-Injection"
B)Pre-injection"
C)End of Injection
D)Injection"

Question 39

At which stage of the Siemens injector operation does the larger surface area above the control piston apply greater pressure than the force of the fuel against the nozzle-valve annulus?
​

A)Post-Injection"
B)Pre-injection"
C)End of Injection
D)Injection"

Question 40

At which stage of the Siemens injector operation does spring pressure close the mushroom valve, causing pressure to build in the control piston control chamber?

A)Post-Injection"
B)Pre-injection"
C)End of Injection
D)Injection"

Question 41

Technician A says that during the end of injection stage, the pressure in the control chamber forces the control piston downward against the nozzle valve, seating the nozzle valve and ending injection. Technician B says that the ECM de-energizes the piezoceramic actuator to cause a rapid return of the actuator to a resting position during the end of injection phase. Who is right?

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

Question 42

Delphi claims the system can generate _____ reduction in emissions.

A)35% to 40%"
B)25% to 30%"
C)15% to 20%
D)45% to 50%"

Question 43

Injector adaptation to compensate for wear and deterioration is performed by an algorithm called:

A)speed pilot control (SPC)"
B)accelerometer pump control"
C)spindle valve (amplified common rail (ACR)
D)accelerometer pilot control"

Question 44

Two technicians are describing the Delphi Multec injector. Technician A says that the spindle valve used by Delphi nozzles is a servo-hydraulic actuator that uses the principles of hydraulic balance to rapidly open and close. Technician B says that the control valve also regulates the operation of a hydraulically balanced nozzle valve. Who is right?

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

Question 45

The spindle valve used by Delphi nozzles is a ____ type of actuator that uses principles of hydraulic balance to open and close rapidly.

A)servo-hydraulic"
B)spindle valve (amplified common rail (ACR))"
C)ball valve
D)piezoceramic"

Question 46

The electric current supplied to Delphi's Multec solenoid CR injectors is at:

A)12 volts"
B)24 volts"
C)36 volts
D)112 volts"

Question 47

Each Delphi injector contains (a) laser printed:

A)dot matrix code"
B)pump compensation codes"
C)injector control codes
D)pump control codes"

Question 48

While two technicians are discussing the purpose of a second electrical control valve, which regulates fuel volume supplied to the inlet of the high-pressure pump, Technician A says the VCV helps reduce fuel consumption. Technician B says the VCV is needed to reduce emissions. Who is correct?

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

Question 49

To reduce parasitic power losses produced by pumping fuel needlessly and to keep fuel temperatures low, pumps now use:

A)outlet pressure metering"
B)inlet pressure metering"
C)outlet volume metering
D)inlet volume metering"

Question 50

An electronically controlled fuel pressure regulator valve that varies pump _____ as commanded by the ECM regulates fuel supplied to the pump and maximum pump.

A)output pressure"
B)inlet pressure"
C)outlet volume
D)inlet volume"

Question 51

Which of the following is required for V engines to synchronize engine firing order with pump strokes?

A)1-piston pumps"
B)2-piston pumps"
C)4-piston pumps
D)8-piston pumps"

Question 52

Two technicians are describing pressure control components of common rail fuel. Technician A says if the high-pressure pump is removed, timing marks on the pump gear and camshaft gear are used to correctly time components during reinstallation. Technician B says that late-model high-pressure pumps are often timed so the peak pressure pulses are phased with the injection events. Who is right?

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

Question 53

To which generation does the high-pressure pump that Bosch purchased from Fiat in the mid-1990s belong, which can develop pressure up to 19,845 psi and was used in the Unijet System?

A)Gen I"
B)Gen II"
C)Gen III
D)Gen IV"

Question 54

At what ratio to engine speed is the high-pressure CP-3 pump driven?

A)1:1"
B)2:1"
C)½ :1
D)4:1"

Question 55

While performing a back leakage test for a second-generation Bosch CR fuel system, the fuel volume was measured to be above specification from the cylinder head. Technician A says the cause could be a leaking quill tube. Technician B says the cause could be one or more injectors with worn-out ball valve seats. Who is correct?

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

Question 56

Which of the following is NOT a strategy that can be used to identify faults on common rail systems?

A)Note the fuel mass"
B)Time the injection"
C)Control the fuel balance
D)Check the battery voltage"

Question 57

To monitor and maintain the emissions levels to their current standard, what legislation requires manufacturers to detect any potential malfunction that could cause emissions to rise above legislated standards?

A)OBDI"
B)OBDII"
C)OBDIII
D)OBDIV"

Question 58

Which of the following will cause an injector to leak or to stay open and inject fuel continuously?

A)Defective rail pressure sensor"
B)Fuel leak"
C)Defective high pressure pump
D)Worn eroded or dirty ball seat"

Question 59

Which one of the following is NOT a fuel return flow that can be measured to identify the faulty component?

A)Injector fuel return"
B)High-pressure pump return"
C)High-pressure relief valve return
D)Secondary filter return"

Question 60

Two technicians are describing measuring injector back leakage (method 1). Technician A says that you start and run the engine at idle, and for 5 minutes, measure and record the volume of fuel accumulating in the graduated cylinders. Technician B says that generally, a defective injector will flow three times the minimum return rate. Who is right?

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