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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"

Correct Answer

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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

Correct Answer

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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) "

Correct Answer

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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.

Correct Answer

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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.

Correct Answer

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What is the auto-ignition temperature of diesel fuel?


A) 420°F"
B) 620°F"
C) 520°F
D) 720°F"

Correct Answer

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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"

Correct Answer

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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"

Correct Answer

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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"

Correct Answer

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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"

Correct Answer

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High intake temperatures can cause thermal damage to:


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

Correct Answer

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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"

Correct Answer

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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"

Correct Answer

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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"

Correct Answer

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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.

Correct Answer

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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"

Correct Answer

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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"

Correct Answer

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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"

Correct Answer

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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.

Correct Answer

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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

Correct Answer

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