Deck 33: Emission Control Systems

Question 1

NO _X emissions increase as combustion temperatures increase.

Answer 1

True

Question 2

A three-way catalytic converter (TWC)stores oxygen when the air/fuel ratio is rich.

Answer 2

True

Question 3

A digital EGR valve has up to _____ solenoids.

A)three
B)four
C)six
D)eight

Answer 3

A

Question 4

NO _X emissions are caused by nitrogen and oxygen uniting at cylinder temperatures above ______.

A)250°F (121°C)
B)500°F (260°C)
C)2,500°F (1,371°C)
D)5,000°F (2,760°C)

Question 5

Lower compression ratios reduce NO _X emissions.

Question 6

A catalytic converter is one of the most effective emission control devices on a vehicle for reducing HC, CO, and NO _X emissions.

Question 7

Port fuel injected engines require intake manifold heating devices.

Question 8

Which of the following systems is designed to reduce NO _X ?

A)PCV
B)EGR
C)AIR
D)EVAP

Question 9

Large amounts of CO₂ in the exhaust are desirable.

Question 10

Excessive oxygen in the exhaust indicates an improper air/fuel mixture.

Question 11

Diesel engines emit less HC, CO, and CO₂ than spark ignition gasoline engines.

Question 12

Hydrocarbon and carbon monoxide exhaust emissions are highest when the engine is cold.

Question 13

OBD-II systems monitor the EVAP system for leaks.

Question 14

An ignition misfire can cause excessive carbon monoxide emissions in the exhaust.

Question 15

Which of the following is NOT related to photochemical smog?

A)CO
B)HC
C)NO _X
D)sunlight

Question 16

Carbon dioxide (CO₂)is a greenhouse gas and may be the major cause of global warming.

Question 17

A digital EGR valve contains up to three electric solenoids that are operated directly by the PCM.

Question 18

A linear EGR valve contains up to three electric solenoids that are operated directly by the PCM.

Question 19

Diesel engines use a PCV system that is nearly identical to a gasoline engine's PCV system, but is designed for a greater rate of flow.

Question 20

_____ emissions are caused largely by unburned fuel from the combustion chambers.

A)CO
B)HC
C)NO _X
D)CO₂

Question 21

While discussing EGR systems with a differential pressure feedback EGR (DPFE)sensor, Technician A says the DPFE sensor sends a signal to the PCM in relation to intake manifold pressure. Technician B says the PCM can make corrections to the EGR flow if the actual flow does not match the desired flow. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 22

The first controlled automotive emission was ______.

A)crankcase vapors
B)tailpipe emissions (HC and CO)
C)NO _X
D)evaporative emissions

Question 23

Technician A says the OBD-II EVAP system leak test monitor will not run if the fuel level is too high. Technician B says the monitor will not run if the fuel level is too low. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 24

Technician A says the EVAP monitor for an OBD-II system determines whether there is sufficient purge flow by varying the purge solenoid duty cycle while monitoring change in STFT. Technician B says the canister vent solenoid must be open during the EVAP pressure test portion of the monitor. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 25

What gas has a rotten egg smell and is caused by sulfur in gasoline chemically reacting with air inside the catalytic converter?

A)sulfur dioxide (SO₂ )
B)hydrogen sulfide (HS)
C)sulphuric acid (H₂SO₄)
D)All the answers are correct.

Question 26

Technician A says the air control valve (or air-switching valve)is a vacuum-operated valve that routes the air from the pump either to the exhaust manifold or to the catalytic converter. Technician B says the air bypass (AIRB)valve (or diverter (AIRD)valve)located between the air pump and the air control valve diverts the air pump output to the atmosphere or air filter during deceleration. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 27

The exhaust gas recirculation system reduces ______.

A)hydrocarbons
B)carbon monoxide
C)oxides of nitrogen
D)All the answers are correct.

Question 28

Technician A says the production of CO₂ is directly related to the amount of fuel consumed; therefore, more fuel-efficient engines produce less CO₂. Technician B says imposing new CAFE (fuel economy)standards will, in effect, reduce CO₂ emissions. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 29

Which of the following is NOT part of an enhanced (OBD-II)evaporative control system?

A)thermal vacuum valve (TVV)
B)canister vent solenoid valve
C)fuel tank vacuum or pressure sensor
D)canister purge solenoid valve

Question 30

Technician A says the EGR vent solenoid is normally open. Technician B says the EGR control solenoid is normally open. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 31

OBD-II canister purge systems are being discussed. Technician A says the canister purge solenoid valve is only open and controlled when the system is in open loop. Technician B says because the system responds to current engine and operating conditions, the purging of the vapors does not affect drivability. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 32

Carbon monoxide is being discussed. Technician A says as the air/fuel ratio becomes richer, the CO levels decrease. Technician B says CO is a colorless, odorless, and highly poisonous gas that can cause death. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 33

An I/M 240 test lasts _____ minutes.

A)two
B)four
C)six
D)eight

Question 34

Technician A says oil in the PCV filter and air cleaner can occur if the PCV valve is restricted or plugged. Technician B says oil buildup inside the throttle body can be an indication of high crankcase pressure. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 35

Technician A says a three-way catalytic converter (TWC)oxidizes carbon monoxide and hydrocarbons into carbon dioxide and water. Technician B says a TWC reduces NO _x into nitrogen and carbon dioxide. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 36

Technician A says HC emissions are caused by incomplete combustion. Technician B says an excessively lean air/fuel mixture may result in cylinder misfiring and high HC emissions. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 37

The enhanced evaporative emission system (OBD-II)can detect a leak in the hoses, lines, fuel tank, or gas cap as small as _____ in.

A).010
B).020
C).040
D).080

Question 38

The AIR system reduces ______.

A)hydrocarbons
B)carbon monoxide
C)both A and B
D)neither A nor B

Question 39

Technician A says the back pressure transducer may be incorporated into the design of the EGR valve. Technician B says negative back pressure transducers use the vacuum in the exhaust between pressure pulses to modulate the EGR flow. Who is correct?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 40

All the following are considered harmful gases EXCEPT:

A)HC
B)CO
C)NO _X
D)O₂

Question 41

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

Question 42

Under what conditions is the EGR valve open?

A)starting
B)idle (warm engine)
C)cruise (warm engine)
D)Wide open throttle

Question 43

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?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 44

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

Question 45

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?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 46

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

Question 47

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

Question 48

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?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 49

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 ____________________.

Question 50

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

Question 51

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

A)450°F (235°C)
B)900°F (500°C)
C)1,200°F (650°C)
D)1,400°F (750°C)

Question 52

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

A)carbon black
B)varnish
C)hydrocarbons
D)sludge

Question 53

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

Question 54

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.

Question 55

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

Question 56

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

Question 57

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

Question 58

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?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 59

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?

A)A only
B)B only
C)both A and B
D)neither A nor B

Question 60

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

Question 61

What is an I/M 240 test?

Question 62

What is the cause of photochemical smog?

Question 63

What is the best way to check whether a catalytic converter is working?

Question 64

Explain why a small PCV valve opening is adequate at idle speed.

Question 65

Describe the purpose of the EVAP system.

Question 66

Why are heated PCV valves used on some vehicles?

Question 67

Where does a secondary air injection system deliver its air supply when the engine is cold and at operating temperature?

Question 68

EGR flow is disabled during throttle openings greater than ___________________ percent

Question 69

How is acid rain related to automotive emissions?

Question 70

Most current light-duty diesel engines use a ___________________ rail injection system.

Question 71

Describe the operation of a digital EGR valve.

Question 72

Describe the purpose of the EGR system.

Question 73

What is the function of glow plugs?

Question 74

What is the vehicle emission control information (VECI)decal and where is it found?