Question 1

A stuck closed PCV valve or restricted hose may cause an accumulation of moisture and sludge in the engine.

Accepted Answer

A) True 
 B)False  True

Question 2

Which of the following is a cause of detonation?

Accepted Answer

A)  a disconnected EGR valve vacuum line 
B)  a leaking EGR valve diaphragm 
C)  the EGR valve stuck in the closed position 
D)  all answers are correct 
A)  a disconnected EGR valve vacuum line 
B)  a leaking EGR valve diaphragm 
C)  the EGR valve stuck in the closed position 
D)  all answers are correct D

Question 3

Identify the causes of high HC emissions.

Accepted Answer

High HC emissions can be caused by the ignition system misfiring, improper ignition timing, lean or excessively rich air/fuel ratio, low cylinder compression, vacuum leaks, and by defective valves, guides, lifters, rings, pistons, and cylinders.

Question 4

If the engine stalls at idle when the EGR is fully opened, the EGR system can be assumed to be working at peak efficiency.

Accepted Answer

A) True 
 B)False

Question 5

Poor EGR gas flow can cause detonation (spark knock).

Accepted Answer

A) True 
 B)False

Question 6

Starting with the 2000 model year, the new EVAP monitor system is designed to detect leaks as small as ___________________ inch.

Accepted Answer

The answer of Starting with the 2000 model year, the...

Question 7

What tool is needed to test a digital EGR valve?

Accepted Answer

A)  scan tool 
B)  a 0.020 inch pin gauge 
C)  jumper wires 
D)  all answers are correct 
A)  scan tool 
B)  a 0.020 inch pin gauge 
C)  jumper wires 
D)  all answers are correct

Question 8

Some AIR systems will set a ___________________ in the PCM if there is a fault in the system.

Accepted Answer

DTC
diagno

Question 9

The customer complains of poor fuel economy. A five-gas analyzer reveals these measurements at 2,500 rpm: HC = 72 ppm, CO = 3.2%, CO2 = 10.3%, O2 = 0.2%, and NOX = 122 ppm. What is the most likely cause?

Accepted Answer

A)  rich mixture 
B)  lean mixture 
C)  lean misfire 
D)  ignition misfire 
A)  rich mixture 
B)  lean mixture 
C)  lean misfire 
D)  ignition misfire

Question 10

What tool is needed to test vacuum-type EGR valves?

Accepted Answer

A)  digital pyrometer 
B)  feeler gauge 
C)  hand vacuum pump 
D)  all answers are correct 
A)  digital pyrometer 
B)  feeler gauge 
C)  hand vacuum pump 
D)  all answers are correct

Question 11

Which of the following gases is NOT considered to be harmful?

Accepted Answer

A)  HC 
B)  CO 
C)  O2 
D)  NOX 
A)  HC 
B)  CO 
C)  O2 
D)  NOX

Question 12

Technician A says an I/M 240 test is four minutes long. Technician B says the test cycle includes acceleration, deceleration, and cruising on an actual road test. Who is correct?

Accepted Answer

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

Question 13

An alternative to the I/M 240 test is the acceleration simulation mode (ASM) test.

Accepted Answer

A) True 
 B)False

Question 14

What can result from a charcoal canister saturated with gasoline?

Accepted Answer

Gasoline vapors may

Question 15

Technician A says a pressure gauge can be inserted into the oxygen sensor bore, and back pressure caused by the catalytic converter can be measured. Technician B says a vacuum gauge can be used to identify a restricted converter. Who is correct?

Accepted Answer

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

Question 16

When the engine is running at peak efficiency, the only gas that is desirable to be at its peak level is ______.

Accepted Answer

A)  CO 
B)  CO2 
C)  HC 
D)  O2 
A)  CO 
B)  CO2 
C)  HC 
D)  O2

Question 17

Nearly all OEMs recommend ___________________ rather than compressed air for pressure testing the EVAP system because it does not support combustion and is unlikely to cause an explosion.

Accepted Answer

The answer of Nearly all OEMs recommend ___________________ rather than...

Question 18

A typical four-gas exhaust analyzer does not measure ____ emissions.

Accepted Answer

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

Question 19

What will result from too little EGR flow?

Accepted Answer

Too little EGR flow

Question 20

A restricted catalytic converter may cause ______.

Accepted Answer

A)  loss of power at high speeds 
B)  stalling after starting 
C)  a drop in engine vacuum as engine rpm increases 
D)  all answers are correct 
A)  loss of power at high speeds 
B)  stalling after starting 
C)  a drop in engine vacuum as engine rpm increases 
D)  all answers are correct

Exam 34: Emission Control Diagnosis and Service

A stuck closed PCV valve or restricted hose may cause an accumulation of moisture and sludge in the engine.

Which of the following is a cause of detonation?

Identify the causes of high HC emissions.

If the engine stalls at idle when the EGR is fully opened, the EGR system can be assumed to be working at peak efficiency.

Poor EGR gas flow can cause detonation (spark knock).

Starting with the 2000 model year, the new EVAP monitor system is designed to detect leaks as small as ___________________ inch.

What tool is needed to test a digital EGR valve?

Some AIR systems will set a ___________________ in the PCM if there is a fault in the system.

The customer complains of poor fuel economy. A five-gas analyzer reveals these measurements at 2,500 rpm: HC = 72 ppm, CO = 3.2%, CO2 = 10.3%, O2 = 0.2%, and NOX = 122 ppm. What is the most likely cause?

What tool is needed to test vacuum-type EGR valves?

Which of the following gases is NOT considered to be harmful?

Technician A says an I/M 240 test is four minutes long. Technician B says the test cycle includes acceleration, deceleration, and cruising on an actual road test. Who is correct?

An alternative to the I/M 240 test is the acceleration simulation mode (ASM) test.

What can result from a charcoal canister saturated with gasoline?

Technician A says a pressure gauge can be inserted into the oxygen sensor bore, and back pressure caused by the catalytic converter can be measured. Technician B says a vacuum gauge can be used to identify a restricted converter. Who is correct?

When the engine is running at peak efficiency, the only gas that is desirable to be at its peak level is ______.

Nearly all OEMs recommend ___________________ rather than compressed air for pressure testing the EVAP system because it does not support combustion and is unlikely to cause an explosion.

A typical four-gas exhaust analyzer does not measure ____ emissions.

What will result from too little EGR flow?

A restricted catalytic converter may cause ______.

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The customer complains of poor fuel economy. A five-gas analyzer reveals these measurements at 2,500 rpm: HC = 72 ppm, CO = 3.2%, CO₂ = 10.3%, O₂ = 0.2%, and NO_X = 122 ppm. What is the most likely cause?