Question 1

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

Accepted Answer

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

Question 2

A leaking evaporative system can be diagnosed using ________.

Accepted Answer

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

Question 3

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

Accepted Answer

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

Question 4

An electric SAI pump is controlled by ________.

Accepted Answer

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

Question 5

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

Accepted Answer

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

Question 6

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?

Accepted Answer

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

Question 7

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

Accepted Answer

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

Question 8

The catalytic converter stores, then burns oxygen.

Accepted Answer

A) True 
 B)False

Question 9

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

Accepted Answer

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

Question 10

The EGR system is designed to lower which exhaust emission?

Accepted Answer

A)   CO
B)   NOx 
C)   HC
D)   CO2

Question 11

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?

Accepted Answer

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

Question 12

At what temperature is the catalytic converter fully effective?

Accepted Answer

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

Question 13

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?

Accepted Answer

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

Question 14

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

Accepted Answer

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

Question 15

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

Accepted Answer

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

Question 16

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

Accepted Answer

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

Question 17

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?

Accepted Answer

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

Question 18

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

Accepted Answer

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

Question 19

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

Accepted Answer

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

Question 20

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

Accepted Answer

A)   CO2 
B)   N2 
C)   O3 
D)   O2

Exam 27: Emission Control Devices Operation and Diagnosis

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

A leaking evaporative system can be diagnosed using ________.

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

An electric SAI pump is controlled by ________.

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

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?

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

The catalytic converter stores, then burns oxygen.

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

The EGR system is designed to lower which exhaust emission?

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?

At what temperature is the catalytic converter fully effective?

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?

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

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

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?

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

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

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