Deck 50: Servicing Maintenance of Exhaust Aftertreatment Systems

Question 1

What is the current national maximum sulfur content permitted in a diesel fuel sold for use in commercial diesel engines in the United States or Canada?

A) 5% S
B) 0.5% S
C) 0.05% S
D) 0.0015% S

Answer 1

0.0015% S

Question 2

What SAE J standard relates specifically to smoke opacity measurement of highway diesel engines?

A) J1584
B) J1667
C) J1708
D) J1939

Answer 2

J1667

Question 3

Technician A says that any vehicle producing excessive NOx emission can be identified by performing an opacity test on its exhaust smoke. Technician B says that PM in the exhaust gas is always identified in J1667 opacity testing. Who is right?

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

Answer 3

Technician B only

Question 4

Which of the following describes how a J1667 exhaust gas, opacity meter functions?

A) mass particle oscillator
B) smoke color comparitor
C) light extinction measurement
D) exhaust gas chemical analysis

Question 5

Technician A says that advancing diesel fuel injection timing by one degree can produce greatly increased NOx in the end gas. Technician B says that retarding diesel fuel injection timing tends to increase the output of HC in the exhaust gas. Who is right?

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

Question 6

What is a reliable tattletale that an aneroid device has been shorted out on a hydromechanical, highway truck diesel engine?

A) increased top end power
B) improved lug performance
C) smoking at rated speed and load
D) puff of exhaust smoke at each upshift

Question 7

Which of the following is NOT a type of aneroid device used on turbo-boosted diesel engines?

A) puff-limiter
B) manifold boost sensor
C) fuel-air ratio control (FARC) valve
D) barometric altitude compensator

Question 8

When the percentage reading increases during opacity testing of diesel engine exhaust gas, what does this indicate?

A) higher NOx emission
B) lower CO emission
C) higher exhaust gas density
D) lower exhaust gas density

Question 9

Technician A says that J1677 opacity testing of a truck diesel engine in humid weather is not considered to be sufficiently reliable for compliance testing. Technician B says that most opacity meters are only accurate to 10% so retesting of marginal vehicles should be considered. Who is correct?

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

Question 10

When using an opacitymeter to perform a J1667 smoke density test, which of the following tests would require a chassis dynamometer?

A) Idle
B) High idle
C) Rated speed and load
D) Maximum puff at throttle snap

Question 11

Technician A says that when ambient temperature drops below 35 degrees Fahrenheit (2 degrees Celsius), outdoor J1667 opacity testing on truck diesel engines does not produce meaningful datA.Technician B says that when outdoor temperatures exceed 80 degrees, a J1667 test should not be performed. Who is correct?

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

Question 12

When performing the required throttle snaps during a J1667 opacity test, how long should each snap be held full travel?

A) 1 second
B) 4 seconds
C) until black smoke is emitted
D) until prompted to release but not more than 4 seconds

Question 13

Technician A says that when performing a J1667 opacity test, the exhaust stack diameter must be correctly entered into the opacity meter instrument or the results will not be meaningful. Technician B says that the ambient temperature must exceed 35 degrees Fahrenheit (2 degrees Celsius) before a valid J1667 opacity test is undertaken. Who is right?

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

Question 14

Which of the following is the recommended method of cleaning a fouled EGR cooler core?

A) boiling in an alkaline soak tank
B) high pressure washing
C) ultrasonic bath cleaning
D) steam cleaning

Question 15

What color is the cap on a DEF reservoir?

A) Silver
B) Blue
C) Red
D) any color will do

Question 16

What is the maximum ambient temperature in which a valid J1667 opacity test can be undertaken?

A) 0 degrees Fahrenheit (-17 degrees Celsius)
B) 32 degrees Fahrenheit (0 degrees Celsius)
C) 60 degrees Fahrenheit (15 degrees Celsius)
D) 86 degrees Fahrenheit (30 degrees Celsius)

Question 17

What temperature does DEF freeze at?

A) 0 degrees Fahrenheit (-17 degrees Celsius)
B) 12 degrees Fahrenheit (-11 degrees Celsius)
C) 32 degrees Fahrenheit (0 degrees Celsius)
D) 60 degrees Fahrenheit (15 degrees Celsius)

Question 18

Technician A says that putting DEF into fuel tanks can void engine warranty. Technician B says that DEF is non-corrosive and will not harm painted surfaces. Who is correct?

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

Question 19

In which of the following applications would you most likely find a diesel particulate filter (DPF) classified as a low temperature filter (LTF)?

A) on pre-2007 school buses
B) on post-2007 school buses
C) on pre-2007 linehaul trucks
D) on post-2007 linehaul trucks

Question 20

When the SCR management circuit defaults the vehicle into a trimback mode, which of the following is the likely problem?

A) clogged DPF dosing injector
B) DPF regeneration required
C) DEF level is low
D) DEF delivery circuit is frozen

Question 21

Technician A says that the EPA Highway Diesel Rule permits NG-fueled engines to output higher NOx emissions. Technician B says that the EPA Highway Diesel Rule focuses on the entire rig and therefore includes factors that influence fuel economy that are not engine-related. Who is correct?

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

Question 22

Technician A says that one of the most common causes of DPF failure is thermal stress during normal regeneration cycles. Technician B says that a crack in the DPF substrate immediately renders the device useless. Who is correct?

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

Question 23

?When a DPF warning light is repeatedly ignored what will result?

A) ?Default to limp home/derate mode
B) ?Automatic regeneration occurs
C) ?Engine shutdown
D) ?Exhaust gas is routed to bypass the DPF

Question 24

What is the current EPA fine levied on any business or individual that either tampers with, or fails to report, tampering with any emissions control device or programming?

A) $3,000
B) $10,000
C) $25,000
D) $37,500

Question 25

?Technician A says that a restricted DPF does not usually trigger limp home/derate until it is 95% plugged. Technician B says that a DPF that is 95% plugged almost always has to be replaced. Who is correct?

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