Deck 14: Air Induction and Crankcase Ventilation Systems

Question 1

Technician A says that it is acceptable practice to clean air filters by using compressed shop air. Technician B says it is better to clean air filters by dropping or lightly tapping the filter against the shop floor. Who is correct?

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

Answer 1

D

Question 2

An engine had a fault code for high crankcase pressure, and its power is derated. Technician A says that the crankcase filter could have frozen when it was exposed to extreme cold conditions. Technician B says that a frozen filter would likely blow engine gaskets and seals rather than cause a derate condition. Who is correct?

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

Answer 2

C

Question 3

What is the primary use for a resonator box on the air inlet of a diesel engine?

A)Increasing air turbulence for improved combustion.
B)Dampening intake noise.
C)Pre-cleaning air of water and dirt.
D)Tuning the intake passage for better airflow.

Answer 3

B

Question 4

Technician A says that diesel engines use more air than gasoline-fueled engines because 1 gallon (3.7 liters) of diesel fuel requires more air to burn than the same amount of gasoline. Technician B says that a diesel engine uses more air to prevent pistons and valves from burning. Who is correct?

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

Question 5

Technician A says that a throttle plate on a late-model diesel engine helps increase the exhaust temperatures for the exhaust aftertreatment catalysts. Technician B says diesel air intake is not throttled. Who is correct?

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

Question 6

The service interval of an air filter is best determined by which of the following?

A)Time in service.
B)Using a trouble light to check the darkness of the paper.
C)Air filter color.
D)Measurement of air filter restriction.

Question 7

Which air filter element will provide the highest filtration efficiency (i.e., which removes the most dirt)?

A)An oil-wetted cotton gauze-style air filter.
B)A dry-type but dirty paper-type filter.
C)An oil bath-type air filter.
D)A new, dry paper-type filter.

Question 8

Which of the following air intake systems will best pre-clean dirt and water from the air intake of an on-highway, diesel-powered vehicle?

A)Front-mounted air inlet.
B)Ram air induction.
C)Composite intake.
D)Side-mounted air inlet.

Question 9

Technician A says that the best practice is to replace air filters on turbocharged engines when the restriction gauge reads 20-25" (51-63 cm) of H2O. Technician B says the filter should be replaced around 10-15" (25-38 cm) H2O to prevent increased fuel consumption caused by a restricted air filter. Who is correct?

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

Question 10

Technician A says that frequent air filter changes help maintain the cleanest quality of air that enters the engine. Technician B says that dirty filters are better than clean filters at allowing cleaner air to enter the engine. Who is correct?

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

Question 11

Technician A says that electric intake heaters are used to reduce cold-start and warm-up emissions. Technician B says that intake air heaters help to shorten the cranking time of a cold engine. Who is correct?

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

Question 12

Technician A says that crankcase coalescing filters are used to minimize particulate emissions from diesel engines. Technician B says that centrifugal separators of air and oil reduce engine oil consumption. 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 a crankcase depression regulator is used to prevent overpressurizing an engine's crankcase. Technician B says that the crankcase depression regulator prevents dirt from entering the engine through seals and gaskets. Who is correct?

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

Question 14

Which of the following reasons best explains why air induction system noise is louder on a diesel engine than on a gasoline-fueled engine?

A)Larger engine displacement.
B)The use of a turbocharger.
C)Smaller clearance volumes in cylinders.
D)Increased amount of valve overlap.

Question 15

Which of the following instruments is the best to use to measure air inlet restrictions?

A)Vacuum gauge.
B)0-5 psi (0-34 kPa) gauge.
C)Water manometer.
D)Mercury manometer.

Question 16

Which of the following methods can best detect a leaking air intake system?

A)Visual inspection.
B)Spraying intake piping and joints with soap and water when the engine is running.
C)Using ether while the engine is running, then listening for an increase in engine speed at leak points.
D)Lube oil analysis to check for silica.

Question 17

Which of the following practices is recommended for servicing a restricted air filter?

A)Cleaning from the inside out with compressed air.
B)Dropping or lightly tapping the filter against the shop floor.
C)Verifying restriction with a trouble light.
D)Replacing the filter.

Question 18

While two technicians are examining a piston crown that has vertical cracks through the edges of the piston's combustion chamber bowl, Technician A suggests the piston crown was not getting properly cooled due to low mass airflow in the combustion chamber during the valve overlap period. Technician B suggests the cracks were caused by inadequate cooling by the oil cooler nozzles. Who is correct?

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

Question 19

What happens to the mass of intake airflow into an engine when the EGR is enabled?

A)Nothing happens.
B)The mass increases.
C)The mass decreases.
D)The mass becomes cooler.

Question 20

What effect will high inlet air temperature combined with high humidity have on engine performance?

A)Increased power compared with cooler, dryer conditions.
B)No difference in power output compared with cooler dryer conditions.
C)Lower power output compared with cooler, dryer conditions.
D)Reduced engine emissions compared with cooler, dryer conditions.

Question 21

A diesel engine of 350 bhp typically requires an air intake capacity of close to ____ cubic feet per minute (cfm).

A)250"
B)500"
C)1,000
D)1200"

Question 22

Which of the following refers to the minimum quantity of air required to completely consume fuel in the combustion chamber with no air or fuel remaining after combustion?

A)Stoichiometric ratio"
B)Control ratio"
C)Fuel air ratio
D)Specific fuel consumption"

Question 23

Since the flame temperature of diesel is near 3,990°F (2,167°C) it will easily melt pistons and burn valves, which of these is important to cool piston crowns and exhaust valves?

A)Adequate supply of air"
B)Adequate supply of fuel"
C)High Sulphur content in fuel
D)Catalytic converter"

Question 24

Dirt ingestion into an engine is referred to as:

A)busting out"
B)abrasive method"
C)sampling method
D)dusting out"

Question 25

Which of the following information need NOT be collected by the technician when taking an oil sample?

A)Sample type (engine, transmission, hydraulic)
B)Oil brand and grade (i.e. Shell Rotella 10w20)"
C)Oil sampling point
D)Engine manufacturer"

Question 26

The results of an oil sampling of a diesel engine show high silicate levels. Which of the following could be the cause?

A)Worn engine bearing and bushings"
B)Worn cylinders"
C)Antifreeze or leaking air intake system
D)Poor combustion quality or over-extended oil service intervals"

Question 27

To identify a problem in the intake system, what are most electronically controlled engines equipped with?

A)Air inlet sensor"
B)EGR pressure sensor"
C)DPF (diesel particulate filter) sensor
D)Air outlet sensor"

Question 28

High intake temperatures can cause thermal damage to:

A)exhaust valves"
B)intake valves"
C)EGR pressure sensor
D)DPF (diesel particulate filter)"

Question 29

Which air inlet sensor is used to provide data regarding atmospheric air pressure for altitude compensation?

A)BARO (barometric pressure sensor)"
B)MAP (manifold absolute pressure)"
C)DPF (diesel particulate filter)
D)MAF (mass airflow)"

Question 30

Technician A says that excessive black or gray smoke emissions from DPF (Diesel Particulate Filter) equipped engines may be caused by restricted air inlet systems or inadequate airflow into the engine. Technician B says that intake temperatures from the intake air sensor are used to modify fuel-injection timing and fuel rates to minimize emissions. Who is right?

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

Question 31

Which of the following sensors measure the weight of air entering the engine and are located after the air filter and before the turbocharger?

A)BARO (barometric pressure sensor)"
B)MAP (manifold absolute pressure)"
C)DPF (diesel particulate Filter)
D)MAF (mass airflow)"

Question 32

MAF (mass airflow) sensors are used primarily on OBDII diesels to detect intake air problems as well as measure:

A)EGR flow"
B)DPF (diesel particulate filter) flow"
C)intake air mass
D)exhaust outlet flow"

Question 33

Technician A says that diesel engines use more air than gasoline-fueled engines because 1 gallon (3.7 liters) of diesel fuel requires more air to burn than the same amount of gasoline. Technician B says that a diesel engine uses more air to prevent pistons and valves from burning. Who is correct?

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

Question 34

The subject of construction features of the air intake system are being discussed. Technician A says that the controls for regulating intake air temperature and EGR flow are commonly found in the air intake system. Technician B says that intake air systems have unique features to minimize the aspiration or entry of water and dirt. Who is right?

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

Question 35

Which of the following is used on some EGR-equipped diesel engines to increase the rate of exhaust gas flowing into the cylinders under some conditions?

A)EGR Valve"
B)Supercharger"
C)Throttle plate
D)Turbocharger"

Question 36

Which of the following tends to create a high degree of intake air swirl?

A)Using two intake ports"
B)Shape of combustion chamber bowl"
C)Using a pre-chamber
D)Using larger intake valves"

Question 37

By doing which of the following does fuel disperse better horizontally, increasing the degree of swirl?

A)Closing the intake valve"
B)Closing the exhaust valve"
C)Closing the throttle
D)Closing the EGR valve"

Question 38

Diesel engines are able to use a large amount of _____ to enhance engine breathing and performance characteristics.

A)valve lift"
B)throttle position"
C)throttle position
D)intake vacuum"

Question 39

Technician A says that frequent air filter changes help maintain the cleanest quality of air that enters the engine. Technician B says that dirty filters are better than clean filters at allowing cleaner air to enter the engine. Who is correct?

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

Question 40

A pre-cleaner will typically remove _____ of all airborne contaminants.

A)80-90%"
B)60-70%"
C)50-60%
D)20-40%"

Question 41

Which of the following located at the elbows of inlet air tubes and in air filter housings assist in removing water and dirt that enter the induction system?

A)Ejector tubes"
B)Injector tubes"
C)Front-mounted air intake stems
D)Side-mounted air intake stems"

Question 42

Two technicians are describing measuring an air filter restriction. Technician A says that you connect a Magnehelic gauge to the clean side of the air filter. Technician B says that you place the engine under load during a road test to operate the engine at maximum boost pressure. Who is right?

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

Question 43

What is the dust-holding capacity of a filter with a pressure drop of 9.9 inches of H₂O?

A)111 grams"
B)228 grams"
C)413 grams
D)530 grams"

Question 44

To obtain the most efficient filtration what should be avoided when servicing air filters?

A)Overservicing"
B)Using wrong brand"
C)Missing the service interval
D)Using a better filter"

Question 45

To prevent engine damage while operating at near maximum threshold temperatures, water is added to the chamber to lower the combustion temperatures. What is this referred to as?

A)Water-Propane injection"
B)Methanol injection"
C)Propane topper
D)Water-methanol injection"

Question 46

Technician A says that nitrous oxide (N2O) will disintegrate into oxygen and nitrogen components in a combustion chamber at 565°F. Technician B says that black or gray smoke under load can be caused by worn camshaft lobes. Who is right?

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

Question 47

Adding ________ can supplement the oxygen in the intake air charge to supply a power boost if additional fuel is added and burned to use up the oxygen in the cylinder.

A)methanol"
B)nitrous oxide"
C)sulfur
D)liquid ether"

Question 48

Which of these systems is impractical to use as a power booster in a diesel engine because the excess air factor diesels operate under would require tremendous amounts of air?

A)Nitrous oxide N2O"
B)Methanol injection"
C)Propane topper
D)Water-methanol injection"

Question 49

Two technicians are discussing boosting power in a diesel engine. Technician A says that turbocharging the engine will increase horsepower. Technician B says that water-methanol systems are occasionally used by diesel performance enthusiasts to lower combustion chamber temperatures. Who is right?

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

Question 50

Technician A says that nitrous oxide (N2O) contains five times as much oxygen as a cubic foot of air. Technician B says that adding nitrous oxide (N₂O) can supplement the oxygen in the intake air charge to supply a power boost. Who is right?

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

Question 51

Which of these results in higher pre-ignition temperatures that help ignite fuel faster for longer burn time and more complete combustion?

A)Lower cetane fuel"
B)Lower compression ratios"
C)Pre-chambers
D)Preheating intake air"

Question 52

What is the auto-ignition temperature of diesel fuel?

A)420°F"
B)620°F"
C)520°F
D)720°F"

Question 53

Ethyl ether is highly flammable; it should never be sprayed into an engine that uses:

A)biodiesel fuel"
B)glow plugs"
C)high compression
D)high cetane fuel"

Question 54

Less exhaust soot and hydrocarbon emissions are produced during cold start and warm-up when using:

A)glow plugs"
B)pre-chambers"
C)low cetane fuel
D)intake heaters"

Question 55

Two technicians are describing air intake system inspection. Technician A says that you visually inspect the air intake system to make sure it is intact. Technician B says that you inspect all ducts, pipes, hoses, tubing, and elbows used to interconnect the system. Who is right?

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

Question 56

Gases escaping past piston rings is called:

A)blowby"
B)soot"
C)slobber
D)slug"

Question 57

Particulate matter (PM) emission found during idle conditions from some diesel engines can be as high as:

A)0.2 g/bhp/hr"
B)0.7 g/bhp/hr"
C)0.8 g/bhp/hr
D)0.4 g/bhp/hr"

Question 58

In a diesel engine, blowby leaking past the rings consists primarily of:

A)water"
B)HC (hydrocarbon) emission"
C)air
D)particulate matter (PM) emission"

Question 59

What are multistage filtration devices used for crankcase ventilation designed to do?

A)Filter out the oil"
B)Coalesce oil and filter out soot"
C)Reduce crankcase pressure
D)Filter engine oil"

Question 60

Two technicians are describing coalescing filtration. Technician A says that crankcase vapors are regulated, so an emission monitor system often uses a crankcase pressure sensor to detect whether the filter is plugged or missing. Technician B says that coalescing filters, which return oil back to the sump tend to increase oil consumption. Who is right?

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