Deck 8: Emission Control and Evaporative Systems

Question 1

If the fuel filler cap leaks, what monitor is designed to detect the leak?

A) the catalyst efficiency monitor
B) the misfire monitor
C) the EVAP system monitor
D) none of the above

Answer 1

C

Question 2

An aftermarket air intake system could affect emission levels.

Answer 2

True

Question 3

The evaporative emissions system reduces the emissions of HC vapors into the atmosphere when the vehicle:

A) is operating at highway speeds
B) is stationary and the engine is idling
C) is parked with the engine off
D) all of the above

Answer 3

D

Question 4

Before performing an emission system diagnosis, the emission control system should be inspected for modification, tampering, and/or missing parts.

Question 5

A PCV valve stuck in the open position may cause a lean air/fuel ratio.

Question 6

Critical sensors that monitor catalyst efficiency are located both upstream and downstream of the catalyst.

Question 7

Technician A says that the PCV is an emission control device. Technician B says that current vehicles monitor the operation of the PCV system. Who is correct?

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

Question 8

If the catalytic converter is working properly, the outlet temperature should be lower than the inlet temperature.

Question 9

An EGR valve that remains open with the engine idling is unlikely to affect engine performance.

Question 10

Gasoline vapors are extremely explosive.

Question 11

The benefits of emission control systems are to:

A) control hydrocarbon fuel vapors from escaping into the atmosphere
B) convert harmful exhaust gases into less harmful emissions before they leave the tailpipe
C) reduce fuel consumption
D) all of the above

Question 12

Technician A says some catalytic converters have an air hose connected from the belt-driven air pump to the oxidation catalyst. Technician B says that in these catalytic converters the air hose from the air pump is connected to the reduction catalyst. Who is correct?

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

Question 13

Technician A says that the EGR system controls and monitors fuel vapor loss. Technician B says that the EVAP system controls and monitors fuel vapor loss. Who is correct?

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

Question 14

The benefits of emission controls are to:

A) reduce pollutants in the exhaust stream
B) control vapor loss into the atmosphere
C) reduce fuel consumption
D) all of the above

Question 15

A defective EGR system could result in an engine performance complaint.

Question 16

Technician A says that in an OBD II vehicle the EVAP system sends fuel tank vapors to a charcoal canister for storage. Technician B says that in an OBD II vehicle, when proper conditions are present, fuel vapors are purged from the charcoal canister into the intake manifold. Who is correct?

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

Question 17

The EGR system is designed to reduce which exhaust emission pollutant?

A) unburned hydrocarbon
B) carbon monoxide
C) carbon dioxide
D) oxides of nitrogen

Question 18

All of the following statements about the EGR valve are true, EXCEPT:

A) the EGR valve creates a controlled vacuum leak between the intake and exhaust manifolds
B) an EGR valve that is stuck closed will cause high NO_X emissions
C) the vacuum to many vacuum actuated EGR valves is controlled by a solenoid
D) an EGR valve that is stuck in the open position will cause detonation

Question 19

Current evaporative emission (EVAP) systems are fully closed to maintain stable fuel tank pressure and virtually eliminate leakage of fuel vapors into the atmosphere.

Question 20

A defective EGR system will cause NO_X emissions to be higher than normal.

Question 21

Describe the operation of the PCV valve as it relates to engine speed.

Question 22

The oxidation catalyst changes HC and CO into what?

Question 23

Catalytic converter damage from severe overheating most likely results from an excessively lean air-fuel mixture, an excessively rich air-fuel mixture, or what other cause?

Question 24

How does the PCM use the PFE sensor signal?

Question 25

What is the purpose of the exhaust gas recirculation system (EGR) monitor, and on what vehicles is it found?

Question 26

Explain the operation of a digital EGR valve.

Question 27

Which of the following is the best definition for the catalytic converter?

A) a device that produces maximum combustion inside the engine
B) a way of cleaning up the exhaust gases after they leave the engine
C) a device that creates extra oxygen to overcome exhaust gases
D) a method of emission control that is now being discontinued

Question 28

An OBD II vehicle has an illuminated MIL and a stored DTC for "Catalyst Efficiency below Threshold" and both the pre- and post-catalyst oxygen sensor signals are fluctuating between 200 mV and 800 mV. What is the most likely cause?

Question 29

The MIL will be illuminated if emissions levels exceed how many times the FTP level?

Question 30

Explain the construction of a modern three-way catalyst and the elements it is made of.

Question 31

What is the role of the EGR valve?

Question 32

A three-way catalyst reduces carbon monoxide, unburned hydrocarbons, and what other pollutant?

Question 33

What does the three-way catalyst do, and what is the conversion efficiency of the catalyst?

Question 34

What does the reduction catalyst change?

Question 35

In what year was the PCV system monitor added to the list of major monitors?

Question 36

Why were the dual-bed catalytic converters developed?

Question 37

What is the catalyst efficiency monitor, and how and why is it performed?

Question 38

When is the three-way catalyst most efficient?

Question 39

Why, in many EGR systems, does the PCM pulse the EVR solenoid on and off?

Question 40

What kind of emissions is caused by unburned fuel left over from the combustion process?

Question 41

Explain the three major pollutants that are regulated vehicle emissions and their sources.