Question 1

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

Accepted Answer

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

Question 2

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

Accepted Answer

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

Question 3

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

Accepted Answer

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

Question 4

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

Accepted Answer

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

Question 5

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?

Accepted Answer

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

Question 6

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

Accepted Answer

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

Question 7

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

Accepted Answer

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

Question 8

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

Accepted Answer

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

Question 9

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?

Accepted Answer

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

Question 10

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

Accepted Answer

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

Question 11

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?

Accepted Answer

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

Question 12

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

Accepted Answer

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

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?

Accepted Answer

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

Question 14

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?

Accepted Answer

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

Question 15

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

Accepted Answer

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

Question 16

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

Accepted Answer

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

Question 17

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?

Accepted Answer