Question 1

The technical term for the soot or the black smoke emitted from a diesel's exhaust pipe is _________________.

Accepted Answer

The answer of The technical term for the soot or...

Question 2

Under what conditions is the EGR valve open?

Accepted Answer

The EGR (Exhaust Gas Recirculation) valve is typically open during cruising conditions with a warm engine to reduce nitrogen oxide emissions by recirculating a portion of the exhaust gases back into the intake manifold. It is usually closed during starting, idle, and wide open throttle to maintain engine performance and stability.

Question 3

Technician A says electronic secondary air systems used on OBD-II vehicles use an electrically driven air pump. Technician B says the check valves in the secondary air tubes prevent converter overheating if the electric air pump fails. Who is correct?

Accepted Answer

The answer of Technician A says electronic secondary air systems...

Question 4

The EVAP systems use a ____________________ canister to collect fuel vapors until they can be purged.

Accepted Answer

The answer of The EVAP systems use a ____________________ canister...

Question 5

Technician A says diesel fuel is denser (heavier)than gasoline. Technician B says diesel fuel is not as good a lubricant as gasoline; therefore wear on piston rings and cylinder walls is a greater problem for diesel engines. Who is correct?

Accepted Answer

Technician A is correct because diesel fuel is indeed denser (heavier) than gasoline. Technician B is incorrect because diesel fuel actually provides better lubrication than gasoline, which helps reduce wear on piston rings and cylinder walls in diesel engines.

Question 6

The I/M 240 test requires the use of a  variable inertia weight  ____________________.

Accepted Answer

The answer of The I/M 240 test requires the use...

Question 7

The two factors that have the greatest effect on vehicle emissions are air/fuel ratio and ___________________ at different spots within the combustion chamber.

Accepted Answer

The answer of The two factors that have the greatest...

Question 8

Technician A says the DPFE (differential pressure feedback EGR)sensor determines the amount of gas flowing through the EGR valve by measuring the pressure drop across an orifice. Technician B says some EGR valves have an NTC thermistor that measures exhaust gas temperature at the outlet of the EGR valve. Who is correct?

Accepted Answer

Both technicians are correct. Technician A is correct in stating that the DPFE sensor measures the pressure drop across an orifice to determine the flow of gas through the EGR valve. Technician B is correct in stating that some EGR valves have an NTC thermistor to measure the exhaust gas temperature at the outlet.

Question 9

Heated air inlet systems, manifold heat control valves (heat risers), and EFE heater grids were used on older cars with carburetors and TBI fuel injection to prevent vaporized fuel from condensing inside the ____________________.

Accepted Answer

The answer of Heated air inlet systems, manifold heat control...

Question 10

NO _X , HC, and CO are changed into harmless gases by the ____________________ in the three way catalytic converter.

Accepted Answer

The answer of NO _X , HC, and CO are...

Question 11

The normal operating temperature for most catalytic converters is about ______.

Accepted Answer

The answer of The normal operating temperature for most catalytic...

Question 12

Blowby gases condense in the crankcase and react with the oil to form ______.

Accepted Answer

Blowby gases condense in the crankcase and react with the oil to form sludge, which is a thick, sticky substance that can accumulate and cause engine problems.

Question 13

During the OBD-II EVAP purge monitor, the duty cycle applied to the purge solenoid is increased. The PCM should see a change in ____________________.

Accepted Answer

The answer of During the OBD-II EVAP purge monitor, the...

Question 14

A ____________________type EGR valve has three electric solenoids. Each of the solenoids and orifices has a different size. The rate of flow is based on the combination of solenoids turned on by the PCM.

Accepted Answer

The answer of A ____________________type EGR valve has three electric...

Question 15

HC and NO _X emissions exposed to sunlight in stagnant air produce ____________________.

Accepted Answer

The answer of HC and NO _X emissions exposed to...

Question 16

The ____________________ system removes blowby gases from the crankcase and recirculates them to the engine intake.

Accepted Answer

The answer of The ____________________ system removes blowby gases from...

Question 17

The PCV system prevents ____________________ gases from escaping to the atmosphere.

Accepted Answer

The answer of The PCV system prevents ____________________ gases from...

Question 18

Technician A says high engine temperatures reduce HC and CO emissions. Technician B says incorrect ignition timing can increase the production of NO _X .Who is correct?

Accepted Answer

High engine temperatures can indeed reduce hydrocarbon (HC) and carbon monoxide (CO) emissions because they promote more complete combustion. Incorrect ignition timing can lead to increased production of nitrogen oxides (NOx), as it can cause the engine to run less efficiently and at higher temperatures, which are conditions that favor NOx formation.

Question 19

Technician A says there is maximum EGR flow only when the vehicle is at a cruising speed with a very light load. Technician B says instead of an EGR valve many late-model engines use variable valve timing (VVT)to trap some exhaust gases in the combustion chamber. Who is correct?

Accepted Answer

Technician A is correct because EGR (Exhaust Gas Recirculation) flow is typically maximized during cruising speeds with light loads to reduce NOx emissions and improve fuel efficiency. Technician B is also correct because many modern engines use Variable Valve Timing (VVT) to control the amount of exhaust gas that remains in the combustion chamber, effectively reducing the need for a traditional EGR valve. This method also helps in reducing emissions and improving engine efficiency.

Question 20

Three types of emissions being controlled in gasoline engines are ____________________, ____________________, and ____________________.

Accepted Answer

The answer of Three types of emissions being controlled in...

Quiz 33: Emission Control Systems

The technical term for the soot or the black smoke emitted from a diesel's exhaust pipe is _________________.

Under what conditions is the EGR valve open?

Technician A says electronic secondary air systems used on OBD-II vehicles use an electrically driven air pump. Technician B says the check valves in the secondary air tubes prevent converter overheating if the electric air pump fails. Who is correct?

The EVAP systems use a ____________________ canister to collect fuel vapors until they can be purged.

Technician A says diesel fuel is denser (heavier) than gasoline. Technician B says diesel fuel is not as good a lubricant as gasoline; therefore wear on piston rings and cylinder walls is a greater problem for diesel engines. Who is correct?

The I/M 240 test requires the use of a variable inertia weight ____________________.

The two factors that have the greatest effect on vehicle emissions are air/fuel ratio and ___________________ at different spots within the combustion chamber.

Heated air inlet systems, manifold heat control valves (heat risers), and EFE heater grids were used on older cars with carburetors and TBI fuel injection to prevent vaporized fuel from condensing inside the ____________________.

NO _X , HC, and CO are changed into harmless gases by the ____________________ in the three way catalytic converter.

The normal operating temperature for most catalytic converters is about ______.

Blowby gases condense in the crankcase and react with the oil to form ______.

During the OBD-II EVAP purge monitor, the duty cycle applied to the purge solenoid is increased. The PCM should see a change in ____________________.

A ____________________type EGR valve has three electric solenoids. Each of the solenoids and orifices has a different size. The rate of flow is based on the combination of solenoids turned on by the PCM.

HC and NO _X emissions exposed to sunlight in stagnant air produce ____________________.

The ____________________ system removes blowby gases from the crankcase and recirculates them to the engine intake.

The PCV system prevents ____________________ gases from escaping to the atmosphere.

Technician A says high engine temperatures reduce HC and CO emissions. Technician B says incorrect ignition timing can increase the production of NO _X .Who is correct?

Technician A says there is maximum EGR flow only when the vehicle is at a cruising speed with a very light load. Technician B says instead of an EGR valve many late-model engines use variable valve timing (VVT) to trap some exhaust gases in the combustion chamber. Who is correct?

Three types of emissions being controlled in gasoline engines are , , and .

Quiz 33: Emission Control Systems

The technical term for the soot or the black smoke emitted from a diesel's exhaust pipe is _________________.

Under what conditions is the EGR valve open?

Technician A says electronic secondary air systems used on OBD-II vehicles use an electrically driven air pump. Technician B says the check valves in the secondary air tubes prevent converter overheating if the electric air pump fails. Who is correct?

The EVAP systems use a ____________________ canister to collect fuel vapors until they can be purged.

Technician A says diesel fuel is denser (heavier) than gasoline. Technician B says diesel fuel is not as good a lubricant as gasoline; therefore wear on piston rings and cylinder walls is a greater problem for diesel engines. Who is correct?

The I/M 240 test requires the use of a variable inertia weight ____________________.

The two factors that have the greatest effect on vehicle emissions are air/fuel ratio and ___________________ at different spots within the combustion chamber.

Heated air inlet systems, manifold heat control valves (heat risers), and EFE heater grids were used on older cars with carburetors and TBI fuel injection to prevent vaporized fuel from condensing inside the ____________________.

NO X , HC, and CO are changed into harmless gases by the ____________________ in the three way catalytic converter.

The normal operating temperature for most catalytic converters is about ______.

Blowby gases condense in the crankcase and react with the oil to form ______.

During the OBD-II EVAP purge monitor, the duty cycle applied to the purge solenoid is increased. The PCM should see a change in ____________________.

A ____________________type EGR valve has three electric solenoids. Each of the solenoids and orifices has a different size. The rate of flow is based on the combination of solenoids turned on by the PCM.

HC and NO X emissions exposed to sunlight in stagnant air produce ____________________.

The ____________________ system removes blowby gases from the crankcase and recirculates them to the engine intake.

The PCV system prevents ____________________ gases from escaping to the atmosphere.

Technician A says high engine temperatures reduce HC and CO emissions. Technician B says incorrect ignition timing can increase the production of NO X .Who is correct?

Technician A says there is maximum EGR flow only when the vehicle is at a cruising speed with a very light load. Technician B says instead of an EGR valve many late-model engines use variable valve timing (VVT) to trap some exhaust gases in the combustion chamber. Who is correct?

Three types of emissions being controlled in gasoline engines are ____________________, ____________________, and ____________________.

NO _X , HC, and CO are changed into harmless gases by the ____________________ in the three way catalytic converter.

HC and NO _X emissions exposed to sunlight in stagnant air produce ____________________.

Technician A says high engine temperatures reduce HC and CO emissions. Technician B says incorrect ignition timing can increase the production of NO _X .Who is correct?

Three types of emissions being controlled in gasoline engines are , , and .