Question 1

While having a discussion, Technician A says that preventing the injection of air into the reduction (NO_X) chamber of the cat helps reduce NO_X. Technician B says that this has no effect of NO_X. Who is correct?

Accepted Answer

Preventing the injection of air into the reduction chamber of the catalytic converter helps reduce NOx emissions, as it promotes the chemical reduction necessary to convert NOx back into nitrogen and oxygen. Technician A is correct.

Question 2

Positive crankcase ventilation systems today are open PCV systems.

Accepted Answer

Modern positive crankcase ventilation (PCV) systems are closed systems, designed to recirculate crankcase gases into the engine for combustion, reducing emissions.

Question 3

A(n) ____________________ is a substance that causes a chemical reaction to occur without undergoing any change to itself.

Accepted Answer

catalyst

Question 4

Carbon monoxide (CO) emissions result when gasoline is not completely burned.

Accepted Answer

Carbon monoxide (CO) is produced as a result of incomplete combustion of gasoline (or any carbon-based fuel), where there is insufficient oxygen to produce carbon dioxide (CO2), leading to the formation of CO instead.

Question 5

____________________ are airborne microscopic particles like dust and soot that are especially prevalent in diesel engine exhaust.

Accepted Answer

The answer of ____________________ are airborne microscopic particles like dust...

Question 6

All of the following statements about the air injection system are true EXCEPT:

Accepted Answer

The air injection system typically uses an electric pump rather than a high-pressure vane-type pump driven by a crankshaft belt to provide air. This system is designed to reduce emissions by injecting air into the exhaust stream, helping to fully combust unburned hydrocarbons and carbon monoxide.

Question 7

The part that is MOST-Likely mounted closer to the engine than the muffler so it can be quickly heated by exhaust is:

Accepted Answer

The catalytic converter is mounted closer to the engine than the muffler so it can quickly reach its operating temperature and efficiently reduce exhaust emissions.

Question 8

CO₂ is a greenhouse gas that traps heat in the atmosphere.

Accepted Answer

CO2, or carbon dioxide, is a greenhouse gas that absorbs infrared radiation and traps heat in the Earth's atmosphere, contributing to the greenhouse effect and global warming.

Question 9

While having a discussion, Technician A says that as the temperature of the engine and air under the hood increases, the evaporation rate of the fuel increases. Technician B says that with the engine running, fresh fuel is always coming into the float bowl. Who is correct?

Accepted Answer

Both statements are correct. Technician A is correct because as the temperature increases, the evaporation rate of the fuel also increases due to the fuel's volatility. Technician B is correct because, in a carbureted system, fresh fuel continuously enters the float bowl as the engine runs to replace the fuel being used.

Question 10

Which of the following is LEAST-Likely a source of emissions?

Accepted Answer

The plenum is part of a vehicle's air intake system and does not directly emit pollutants, unlike the crankcase, evaporation, and exhaust, which are all sources of emissions.

Question 11

To regulate EGR more accurately, some EGR systems use ____________________, in the same way as fuel injection systems, to rapidly cycle an EGR vacuum control solenoid on and off.

Accepted Answer

The answer of To regulate EGR more accurately, some EGR...

Question 12

The heart of the evaporative emission system is a(n) ____________________ canister.

Accepted Answer

The answer of The heart of the evaporative emission system...

Question 13

Aluminum is an oxide of alumina that is very porous.

Accepted Answer

Aluminum is a metallic element, while alumina (Al2O3) is an oxide of aluminum, not the other way around.

Question 14

The system that is MOST-Likely used to prevent the emission of hydrocarbons  in blowby gases from the crankcase by scavenging them from the crankcase and reintroducing them into the combustion chambers is:

Accepted Answer

The PCV (Positive Crankcase Ventilation) system is designed to prevent the emission of hydrocarbons in blowby gases from the crankcase by scavenging them and reintroducing them into the combustion chambers, thus reducing pollution and improving engine efficiency.

Question 15

All of the following statements are true EXCEPT:

Accepted Answer

Gasoline expands on a hot day, rather than contracts. This expansion is due to the increase in temperature, which causes the gasoline molecules to move more rapidly and take up more space.

Question 16

____________________ is produced when hydrocarbons and oxides of nitrogen react with sunlight to form a dirty yellow-brown haze in the air.

Accepted Answer

The answer of ____________________ is produced when hydrocarbons and oxides...

Question 17

An oxidizing catalyst starts to work at temperatures between ____.

Accepted Answer

The answer of An oxidizing catalyst starts to work at...

Question 18

Three-way catalytic converters use ____, or sometimes palladium, as a catalyst for their reduction portion (the part that controls NO_X).

Accepted Answer

Rhodium is used in the reduction portion of three-way catalytic converters to control nitrogen oxides (NOx), alongside platinum and sometimes palladium for other reactions within the converter.

Question 19

Which of the following statements is LEAST-Likely true?

Accepted Answer

The rollover valve is designed to block the fuel line in the event of a vehicle rollover to prevent fuel leakage, not specifically when the vehicle is started. This makes option B the least likely true statement among the options provided.

Question 20

Exhaust backpressure is a good indicator of engine load.

Accepted Answer

Exhaust backpressure increases with engine load because as the engine works harder to produce more power, it generates more exhaust gases, leading to higher backpressure.

Quiz 43: Emission Control System Fundamentals

While having a discussion, Technician A says that preventing the injection of air into the reduction (NO_X) chamber of the cat helps reduce NO_X. Technician B says that this has no effect of NO_X. Who is correct?

Positive crankcase ventilation systems today are open PCV systems.

A(n) ____________________ is a substance that causes a chemical reaction to occur without undergoing any change to itself.

Carbon monoxide (CO) emissions result when gasoline is not completely burned.

____________________ are airborne microscopic particles like dust and soot that are especially prevalent in diesel engine exhaust.

All of the following statements about the air injection system are true EXCEPT:

The part that is MOST-Likely mounted closer to the engine than the muffler so it can be quickly heated by exhaust is:

CO₂ is a greenhouse gas that traps heat in the atmosphere.

While having a discussion, Technician A says that as the temperature of the engine and air under the hood increases, the evaporation rate of the fuel increases. Technician B says that with the engine running, fresh fuel is always coming into the float bowl. Who is correct?

Which of the following is LEAST-Likely a source of emissions?

To regulate EGR more accurately, some EGR systems use ____________________, in the same way as fuel injection systems, to rapidly cycle an EGR vacuum control solenoid on and off.

The heart of the evaporative emission system is a(n) ____________________ canister.

Aluminum is an oxide of alumina that is very porous.

The system that is MOST-Likely used to prevent the emission of hydrocarbons in blowby gases from the crankcase by scavenging them from the crankcase and reintroducing them into the combustion chambers is:

All of the following statements are true EXCEPT:

____________________ is produced when hydrocarbons and oxides of nitrogen react with sunlight to form a dirty yellow-brown haze in the air.

An oxidizing catalyst starts to work at temperatures between ____.

Three-way catalytic converters use ____, or sometimes palladium, as a catalyst for their reduction portion (the part that controls NO_X) .

Which of the following statements is LEAST-Likely true?

Exhaust backpressure is a good indicator of engine load.

Quiz 43: Emission Control System Fundamentals

While having a discussion, Technician A says that preventing the injection of air into the reduction (NOX) chamber of the cat helps reduce NOX. Technician B says that this has no effect of NOX. Who is correct?

Positive crankcase ventilation systems today are open PCV systems.

A(n) ____________________ is a substance that causes a chemical reaction to occur without undergoing any change to itself.

Carbon monoxide (CO) emissions result when gasoline is not completely burned.

____________________ are airborne microscopic particles like dust and soot that are especially prevalent in diesel engine exhaust.

All of the following statements about the air injection system are true EXCEPT:

The part that is MOST-Likely mounted closer to the engine than the muffler so it can be quickly heated by exhaust is:

CO2 is a greenhouse gas that traps heat in the atmosphere.

While having a discussion, Technician A says that as the temperature of the engine and air under the hood increases, the evaporation rate of the fuel increases. Technician B says that with the engine running, fresh fuel is always coming into the float bowl. Who is correct?

Which of the following is LEAST-Likely a source of emissions?

To regulate EGR more accurately, some EGR systems use ____________________, in the same way as fuel injection systems, to rapidly cycle an EGR vacuum control solenoid on and off.

The heart of the evaporative emission system is a(n) ____________________ canister.

Aluminum is an oxide of alumina that is very porous.

The system that is MOST-Likely used to prevent the emission of hydrocarbons in blowby gases from the crankcase by scavenging them from the crankcase and reintroducing them into the combustion chambers is:

All of the following statements are true EXCEPT:

____________________ is produced when hydrocarbons and oxides of nitrogen react with sunlight to form a dirty yellow-brown haze in the air.

An oxidizing catalyst starts to work at temperatures between ____.

Three-way catalytic converters use ____, or sometimes palladium, as a catalyst for their reduction portion (the part that controls NOX) .

Which of the following statements is LEAST-Likely true?

Exhaust backpressure is a good indicator of engine load.

While having a discussion, Technician A says that preventing the injection of air into the reduction (NO_X) chamber of the cat helps reduce NO_X. Technician B says that this has no effect of NO_X. Who is correct?

CO₂ is a greenhouse gas that traps heat in the atmosphere.

Three-way catalytic converters use ____, or sometimes palladium, as a catalyst for their reduction portion (the part that controls NO_X) .