Deck 33: Emission Control Systems

Question 1

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

A) CO
B) HC
C) NO_X
D) CO₂

Answer 1

B

Question 2

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

Answer 2

True

Question 3

Which of the following is NOT related to photochemical smog?

A) CO
B) HC
C) NO_X
D) sunlight

Answer 3

A

Question 4

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

Question 5

OBD-II systems monitor the EVAP system for leaks.

Question 6

Lower compression ratios reduce NO_X emissions.

Question 7

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

Question 8

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

Question 9

A digital EGR valve has up to _____ solenoids.

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

Question 10

Large amounts of CO₂ in the exhaust are desirable.

Question 11

NO_X emissions increase as combustion temperatures increase.

Question 12

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

Question 13

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

Question 14

Which of the following systems is designed to reduce NO_X?

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

Question 15

A catalytic converter is one of the most effective emission control devices on a vehicle for reducing HC, CO, and NO_X emissions.

Question 16

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

Question 17

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 18

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 19

Port fuel injected engines require intake manifold heating devices.

Question 20

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

Question 21

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 22

The exhaust gas recirculation system reduces ______.

A) hydrocarbons
B) carbon monoxide
C) oxides of nitrogen
D) all answers are correct

Question 23

The first controlled automotive emission was ______.

A) crankcase vapors
B) tailpipe emissions [HC and CO]
C) NO_X
D) evaporative emissions

Question 24

All the following are considered harmful gases EXCEPT:

A) HC
B) CO
C) NO_X
D) O₂

Question 25

Detonation sensors are being discussed. Technician A says most detonation sensors produce an analog signal. Technician B says the detonation sensor may be mounted in the exhaust. Who is correct?

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

Question 26

An I/M 240 test lasts _____ minutes.

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

Question 27

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 28

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 29

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 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

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 32

The AIR system reduces ______.

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

Question 33

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 34

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 35

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 answers are correct

Question 36

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 37

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 38

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 39

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 40

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 41

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 42

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 43

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 44

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

Question 45

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

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

Question 46

The I/M 240 test requires the use of a chassis ____________________.

Question 47

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 48

HC and NO_X emissions exposed to sunlight in stagnant air produce ____________________.

Question 49

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 50

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

Question 51

Under what conditions is the EGR valve open?

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

Question 52

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 53

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

Question 54

NO_X, HC, and CO are changed into harmless gases by the ____________________ in the three way catalytic converter.

Question 55

Technician A says diesel fuel is a light fuel oil and 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 56

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 57

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 58

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

Question 59

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

Question 60

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 61

Why are heated PCV valves used on some vehicles?

Question 62

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

Question 63

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

Question 64

Describe the operation of a digital EGR valve.

Question 65

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

Question 66

What is the function of glow plugs?

Question 67

Describe the purpose of the EVAP system.

Question 68

EGR flow is disabled during throttle openings of more than ___________________ percent

Question 69

Describe the purpose of the EGR system.

Question 70

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

Question 71

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

Question 72

How is acid rain related to automotive emissions?

Question 73

What is an I/M 240 test?