Deck 27: Emission Control Devices Operation and Diagnosis

Question 1

The ORVR system is designed to capture ________ during re-fueling.

A) water vapor
B) fuel vapors
C) excess liquid
D) reserve fuel

Answer 1

B

Question 2

A state inspection of the EVAP system includes ________.

A) checking the level of fuel in the tank
B) pressurizing the EVAP system
C) testing the gas cap for proper sealing
D) Both A and B

Answer 2

D

Question 3

The EGR system is designed to lower which exhaust emission?

A) CO
B) NO_x
C) HC
D) CO₂

Answer 3

B

Question 4

All these are causes of catalytic converter failure EXCEPT ________.

A) contamination
B) excessive water vapor
C) incorrect air/fuel mixture
D) excessive temperature

Question 5

Which exhaust emission is formed by high combustion chamber temperatures?

A) HC
B) NO_x
C) CO₂
D) CO

Question 6

EGR is usually not required under which of these engine conditions?

A) Idle
B) Wide open throttle
C) Cold engine
D) All of these are correct.

Question 7

Which type of EGR valve requires a positive exhaust system pressure to operate?

A) Negative backpressure
B) Digital
C) Linear
D) Positive backpressure

Question 8

The following statements are all correct EXCEPT ________.

A) some systems monitor EGR operation by using a pressure feedback EGR sensor
B) a potentiometer is used to determine EGR valve position on many OBD-II systems
C) low restriction exhaust systems will have no effect on EGR system operation
D) the PCM controls vacuum applied to vacuum operated EGR valves

Question 9

How many solenoids are contained in the GM digital EGR valve?

A) None
B) One
C) Three
D) Two

Question 10

All of the following statements are correct EXCEPT ________.

A) linear EGR systems require exhaust backpressure
B) many vehicles use the MAP sensor to monitor EGR operation
C) some systems use a delta pressure feedback system to monitor EGR operation by measuring exhaust system pressure
D) OBD-II vehicles require monitoring of the EGR system

Question 11

Which of the following are symptoms of a fault in the EGR system?

A) Detonation during acceleration or cruise
B) Rough idle and stalling
C) Excessive NO_x emissions
D) All of these

Question 12

When performing an EGR system test on a vacuum operated EGR valve, how much should intake manifold vacuum decrease when the EGR valve is opened at fast idle?

A) 1-2 in. Hg.
B) 6-8 in. Hg.
C) 6-8 PSI
D) 14.7 PSI

Question 13

Technician A says that carbon should be cleaned out after installing a new EGR valve. Technician B cleans the EGR exhaust passages by using a stranded metal cable. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 14

A vehicle comes into the shop and the technician retrieves the diagnostic code P0401 "EGR flow insufficient." Which of these could be the cause?

A) EGR valve stuck open
B) Electrical wiring shorted
C) Clogged EGR ports or passages
D) All of these are correct.

Question 15

Technician A says that PCV valves should rattle when shaken. Technician B says that defective PCV systems may cause leaking engine seals. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 16

What term is used to describe combustion gasses leaking past cylinder rings?

A) Manifold pressure
B) Crankcase build-up
C) Sludge
D) Blow by

Question 17

Technician A says that some crankcase vent systems use a calibrated orifice instead of a PCV valve. Technician B says that turbocharged engines often use an oil/water separator in the PCV system. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 18

Technician A says that a 3 x 5 card should be held against the oil fill opening if the PCV system is operating correctly. Technician B says that if a PCV valve rattles, it definitely is good. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 19

Which component sends fresh air to the catalytic converter to help oxidize emissions?

A) AIR pump
B) PCV valve
C) Thermostatic air cleaner
D) EGR valve

Question 20

Which device protects the air pump from reverse exhaust pressure?

A) IAC valve
B) Check valve
C) EGR valve
D) PCV valve

Question 21

Where is air from the AIR pump directed when the engine is cold?

A) Air cleaner
B) Atmosphere
C) Catalytic converter
D) Exhaust manifold

Question 22

An electric SAI pump is controlled by ________.

A) the PCM
B) a vacuum switch
C) exhaust pressure
D) manifold vacuum

Question 23

Technician A says that the electric AIR pump requires periodic maintenance. Technician B says that if the AIR pump is good, the oxygen sensors should read 850 mV or more when the AIR pump is energized. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 24

Technician A says that CO and HC levels should increase if the AIR hoses are pinched off. Technician B says that a defective drive belt may cause AIR system problems. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 25

Technician A says that the location of the catalytic converter is not important. Technician B says that the catalytic converter should be positioned as far from the engine as possible. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 26

At what temperature is the catalytic converter fully effective?

A) 100 deg F
B) 1000 deg F
C) 420 deg F
D) 500 deg F

Question 27

A vehicle failed an emission test due to high carbon monoxide and hydrocarbons in the exhaust gas. What could be the cause?

A) Overfilling the fuel tank
B) Saturated EVAP charcoal canister
C) Either A or B
D) Neither A nor B

Question 28

All of these are components of smog EXCEPT ________.

A) AIR
B) NO_x
C) Fog
D) HC

Question 29

Smog contains ________, which is an irritant to lungs and eyes.

A) CO₂
B) N₂
C) O₃
D) O₂

Question 30

The OBD-II evaporative emission system monitor on a 2008 vehicle can detect a hole as small as ________.

A) 0.200" diameter
B) 0.020" diameter
C) 0.400" diameter
D) 0.040" diameter

Question 31

A leaking evaporative system can be diagnosed using ________.

A) Nitrogen gas and headphones
B) A smoke machine
C) Either of these
D) Neither of these

Question 32

An evaporative emission system leak detection pump adds ________ to the fuel tank in order to check for leaks.

A) slight pressure
B) pressure pulses
C) a vacuum
D) oxygen

Question 33

A vacuum gauge is being used to check for a restricted exhaust system. The vacuum at idle is 18 in. Hg. Which of these results indicates a restriction?

A) Vacuum at 2,500 RPM is 22 in. Hg.
B) Vacuum at 2,500 RPM is 19 in. Hg.
C) Vacuum at 2,500 RPM is 9 in. Hg.
D) Not enough information to diagnose

Question 34

The catalytic converter stores, then burns oxygen.

Question 35

This drawing shows a catalytic converter with exhaust gases entering the CAT. What are the gases changed to at the CAT outlet?

A) HCO and CO
B) NO_x
C) H₂O and CO₂
D) Both A and C

Question 36

The O₂ sensors in this OBD II system are sending a voltage signal as shown. What conclusion can be made about the catalytic converter?

A) The CAT is not working correctly
B) The CAT is working correctly
C) The engine is not running, so the CAT is not functioning
D) Not enough information