Deck 20: Fuel Injection Basics and Governor Principles

Question 1

How is an engine that is electronically managed, controlled?

A) hydraulic governor
B) electrical switches
C) computer
D) mechanical governor

Answer 1

computer

Question 2

When a diesel engine is said to be hydromechanically managed, which of the following components would NOT be used?

A) fuel injectors
B) computer
C) mechanical governor
D) fuel transfer pump

Answer 2

computer

Question 3

Which variable defines the actual size of fuel droplets emitted from a diesel injector?

A) charging pressure
B) orifii size
C) injection pressure
D) number of multipulse events

Answer 3

injection pressure

Question 4

Why does retarding injection timing tend to produce higher HC emissions?

A) increases injection lag
B) reduces time available for combustion
C) increases ignition lag
D) increases combustion temperatures

Question 5

The precise control of injected fuel quantity in a diesel engine is known as:

A) atomization
B) pressurization
C) metering
D) measuring

Question 6

Which of the following has the most influence on the power output of a diesel engine?

A) turbocharger boost pressure
B) air flow through intake plenum
C) injected fuel quantity
D) atomized droplet sizing

Question 7

Fuel injected per crank angle degree in a diesel fuel system is known as:

A) injection rate
B) injection quantity
C) atomization rate
D) delivery rate

Question 8

In a current direct injected diesel engine governed at 2000 rpm, what droplet size range must the injection system produce?

A) 1 - 10 microns
B) 10 - 100 microns
C) 100 - 200 microns
D) 200 - 500 microns

Question 9

Which two factors define the droplet sizing emitted from a diesel fuel injector?

A) pressure and flow area
B) engine speed and load
C) timing and charge pressure
D) air flow and boost pressure

Question 10

What state is atomized fuel in?

A) vapor
B) aerated
C) gas
D) liquid

Question 11

In which of the following engine locations would ignition typically take place?

A) 30 degrees BTDC
B) 3 degrees BTDC
C) 15 degrees ATDC
D) 90 degrees ATDC

Question 12

When fuel condenses on the piston crown during injection, which of the following can result?

A) pitting
B) pre-ignition
C) pinging
D) detonation

Question 13

Technician A says recent CR fuel systems can produce injection pressures exceeding 2,450bar(35,000 psi). Technician B says that larger size fuel droplets are produced when fuel injection pressure are close to their maximum. Who is correct?

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

Question 14

How much mechanical leverage can result when a piston throw on the crankshaft forms a 90 degree angle to the piston on its downstroke?

A) none
B) minimum
C) 50% of maximum
D) maximum

Question 15

When a crankshaft throw is positioned at exactly TDC, how much mechanical leverage can it apply to the crankshaft?

A) none
B) minimum
C) 50% of maximum
D) maximum

Question 16

Where is the ideal location for peak cylinder pressure to occur on the power stroke?

A) TDC
B) 15 degrees ATDC
C) 45 degrees ATDC
D) 90 degrees ATDC

Question 17

What is the reason for advancing injection timing as engine speed increases?

A) real time available for combustion decreases
B) real time available for combustion increases
C) less air in engine cylinder
D) more air in engine cylinder

Question 18

When a 4-stroke cycle engine rotates at 2000 rpm, how many power strokes occur in any one of its cylinders per second?

A) 500
B) 100
C) 17
D) 8

Question 19

Technician A says that multipulse injection can result in smoother engine operation. Technician B says that multipulse injection today can mean breaking up fuel injection into up to 7 events per cycle. Who is correct?

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

Question 20

Technician A says that diesel fuel droplets burn from the inside out. Technician B says that small fuel droplets heat up to their ignition temperature more rapidly than larger droplets. Who is correct?

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

Question 21

What do most mechanical governors on truck engines use to sense engine speed?

A) flyweights
B) thrust collar
C) fuel pressure
D) oil pressure

Question 22

Why is torque rise significant to a truck driver?

A) indicates how fast the engine will turn
B) indicates peak power available
C) defines upper and lower gear shift points
D) define the lugging ability of an engine

Question 23

If the main governor spring in a mechanical governor was worn out, what would be the likely performance symptom?

A) engine runaway
B) low power
C) erratic idle
D) excessive top end rpm

Question 24

Which of the following terms means the same thing as top engine limit (TEL) in a highway truck engine?

A) peak torque
B) rated speed
C) overrun rpm
D) high idle

Question 25

Which of the following governing classifications would allow the accelerator pedal in a truck diesel engine to respond like that in an automobile?

A) limiting speed
B) variable speed
C) isochronous
D) all-speed governor

Question 26

A truck has a governor classified a variable speed and the driver is moving the vehicle down a highway using 50% pedal travel. In order to maintain the same road speed to climb a hill, what should the driver do initially?

A) increase pedal angle
B) decrease pedal angle
C) nothing: hold pedal position
D) use the throttle cable

Question 27

A truck diesel engine rated speed governed at 2000 rpm has a droop curve of 10%. What should be the high idle speed?

A) 2000 rpm
B) 200 rpm
C) 1800 rpm
D) 2200 rpm

Question 28

Which of the following is a common toggle option in the software of an electronically managed diesel engine?

A) min-max governing
B) LS or VS governing
C) VS or isochronous governing
D) mechanical or hydraulic governing

Question 29

If a truck diesel engine is said to be operating in isochronous mode, which of the following is it most likely doing?

A) using the PTO to pump load
B) running a long downhill gradient
C) climbing uphill
D) running in toque rise

Question 30

Which of the following would indicate the lowest engine rpm?

A) peak torque
B) high idle
C) engine lug
D) droop curve

Question 31

An engine has a rated speed of 2000 rpm and has 40% torque rise. At what rpm would you expect to find peak torque?

A) 2000 rpm
B) 800 rpm
C) 1200 rpm
D) 2800 rpm

Question 32

When a hydromechanical governor throttle is snapped (to full fuel request) under no-load, engine rpm temporarily exceeds the high idle speed. What is the term used to describe this condition?

A) hunting
B) top end limit
C) deadband
D) overrun

Question 33

When engine rpm rises and falls at random with no rhythmic pattern, the term used to describe this conditions is:

A) hunting
B) insensitivity
C) speed drift
D) stability

Question 34

A driver complains that when his truck engine is under load, whenever he removes his foot from the accelerator pedal, engine rpm drops below specified idle speed and occasionally stalls. Which of the following terms is used to describe this condition?

A) wide open throttle
B) underrun
C) overrun
D) droop

Question 35

What is the term used to describe the graduated fuel deration (reduction in maximum fuel) that takes place between rated speed rpm and high idle rpm?

A) drop-off
B) deadband
C) governor cut-off
D) droop curve

Question 36

Which two truck engine manufacturers were known for favoring variable speed type governors on hydromechanical engines?

A) Cummins and International
B) Hino and Detroit Diesel
C) Mack and Caterpillar
D) Mercedes Benz and Mitsubishi

Question 37

What type of governor is used in almost all current truck diesel engines?

A) mechanical
B) hydraulic servo
C) pneumatic
D) electronic

Question 38

Technician A says that limiting speed (LS) governing is not an option in most electronically controlled engines. Technician B tells a truck driver that he can program his truck to operate in variable speed (VS) governing mode. Who is correct?

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

Question 39

What replaces the governor functions of a hydromechanical engine on a current, electronically controlled engine?

A) sensors
B) electronic unit injectors
C) ECM programmed software instructions
D) drive-by-wire accelerator pedal

Question 40

?Which of the following would represent the fastest engine rpm?

A) ?High idle
B) ?Rated speed
C) ?Peak torque rpm
D) ?Lug rpm

Question 41

?If the signal from the accelerator pedal sensor is lost, which of the following is the likely outcome?

A) ?Engine shutdown
B) ?Engine operates in default mode
C) ?Engine operates at rated rpm
D) ?Engine runaway