Question 1

When you use the scan tool to command EGR valve operation, the amount of valve opening is displayed on the scan tool and should MOST-Likely be within:

Accepted Answer

A) 1% of the specified amount. 
B) 3% of the specified amount. 
C) 5% of the specified amount. 
D) 10% of the specified amount. 
A) 1% of the specified amount. 
B) 3% of the specified amount. 
C) 5% of the specified amount. 
D) 10% of the specified amount. D

Question 2

The tool MOST-Likely designed to reduce normal exhaust emissions is:

Accepted Answer

A) pyrometer 
B) catalytic converter 
C) charcoal canister 
D) thermistor 
A) pyrometer 
B) catalytic converter 
C) charcoal canister 
D) thermistor B

Question 3

How would you perform a snap test?

Accepted Answer

To perform the snap test:
1. Snap the throttle open and let it drop back down to idle. This loads the cat with fuel.
2. Watch O₂ and CO. Check the rise in O₂ as CO increases. O2 will continue to rise after the CO peaks, but this is not important. What is important is the O₂ level at the point of peak CO.

Question 4

Which of the following is LEAST-Likely a typical symptom for EGR system problems?

Accepted Answer

A) Hesitation when cold 
B) Detonation 
C) Increased cooling system temperature 
D) Converter light off 
A) Hesitation when cold 
B) Detonation 
C) Increased cooling system temperature 
D) Converter light off

Question 5

How would you locate a leak in the crankcase ventilation system?

Accepted Answer

A smoke tester is the best way to check

Question 6

A running engine will always have at least ____ CO2.

Accepted Answer

A) 1% 
B) 2% 
C) 3% 
D) 4% 
A) 1% 
B) 2% 
C) 3% 
D) 4%

Question 7

High HC is caused by an excessive amount of unburned ____________________.

Accepted Answer

The answer of High HC is caused by an excessive...

Question 8

On distributor ignition systems, ____________________ pressure can cause oil to migrate up the distributor shaft and into the distributor.

Accepted Answer

The answer of On distributor ignition systems, ____________________ pressure can...

Question 9

____ are caused by gasket failures that prevent the ventilation system from operating as designed.

Accepted Answer

A) Evaporative leaks 
B) Oil leaks 
C) Vacuum hose leaks 
D) Manifold leaks 
A) Evaporative leaks 
B) Oil leaks 
C) Vacuum hose leaks 
D) Manifold leaks

Question 10

What are the steps involved in testing the PCV valve?

Accepted Answer

To test the PCV valve:
PCV valves can be

Question 11

High EGR flow results in undercalculation of the fuel and a lean air-fuel mixture, and low EGR flow drives the mixture rich.

Accepted Answer

A) True 
 B)False

Question 12

Vacuum problems can be caused by incorrect hose routing or defects with a backpressure transducer, thermal switching valve, or solenoid.

Accepted Answer

A) True 
 B)False

Question 13

The measurement 1 ppm means that out of every thousand parts of an exhaust sample, one part is HC.

Accepted Answer

A) True 
 B)False

Question 14

How would you use a flowmeter to check for EVAP leaks?

Accepted Answer

On a warm engine, after 2 minutes at idl

Question 15

Which of the following statements is LEAST-Likely true?

Accepted Answer

A) NOX emissions are highest at a point near stoichiometric. 
B) NOX emissions are more when the mixture is leaner than 16:1. 
C) The catalytic converter is more efficient at controlling HC and CO when the air-fuel mixture is stoichiometric. 
D) A rich mixture will cool combustion and has less O2, so NOX emissions are lower. 
A) NOX emissions are highest at a point near stoichiometric. 
B) NOX emissions are more when the mixture is leaner than 16:1. 
C) The catalytic converter is more efficient at controlling HC and CO when the air-fuel mixture is stoichiometric. 
D) A rich mixture will cool combustion and has less O2, so NOX emissions are lower.

Question 16

All of the following statements are true EXCEPT:

Accepted Answer

A) when intake or exhaust is restricted the engine cannot bring in enough fresh air and fuel. 
B) one cause of an air-fuel mixture that is too lean to burn is a leak in the intake system. 
C) after a misfire, whatever remains in the cylinder ends up in the exhaust stream, decreasing the HC level. 
D) high HC can be caused by a defective spark plug or problems with ignition wiring. 
A) when intake or exhaust is restricted the engine cannot bring in enough fresh air and fuel. 
B) one cause of an air-fuel mixture that is too lean to burn is a leak in the intake system. 
C) after a misfire, whatever remains in the cylinder ends up in the exhaust stream, decreasing the HC level. 
D) high HC can be caused by a defective spark plug or problems with ignition wiring.

Question 17

CO is oxidized into CO2 by the catalytic converter and ____________________ system.

Accepted Answer

Question 18

A leaking or misplaced gasket to a valve cover or intake manifold can leak enough air to render the PCV system inoperable.

Accepted Answer

A) True 
 B)False

Question 19

All of the following statements are true EXCEPT:

Accepted Answer

A) on a late-model car running at 2,000 rpm with a hot converter, normal readings from the exhaust pipe should be above 0.1% (with an air injection system disabled). 
B) like HC, O2 is not formed during combustion so it should be consumed during each combustion cycle. 
C) before combustion, the incoming air is 21% O2. 
D) when checking O2 emissions in the exhaust, it is very important that there be no supplemental air or exhaust system leak. 
A) on a late-model car running at 2,000 rpm with a hot converter, normal readings from the exhaust pipe should be above 0.1% (with an air injection system disabled). 
B) like HC, O2 is not formed during combustion so it should be consumed during each combustion cycle. 
C) before combustion, the incoming air is 21% O2. 
D) when checking O2 emissions in the exhaust, it is very important that there be no supplemental air or exhaust system leak.

Question 20

What are some of the possible causes of spark knock?

Accepted Answer

The following are other possible causes

Exam 44: Emission Control System Service

When you use the scan tool to command EGR valve operation, the amount of valve opening is displayed on the scan tool and should MOST-Likely be within:

The tool MOST-Likely designed to reduce normal exhaust emissions is:

How would you perform a snap test?

Which of the following is LEAST-Likely a typical symptom for EGR system problems?

How would you locate a leak in the crankcase ventilation system?

A running engine will always have at least ____ CO2.

High HC is caused by an excessive amount of unburned ____________________.

On distributor ignition systems, ____________________ pressure can cause oil to migrate up the distributor shaft and into the distributor.

____ are caused by gasket failures that prevent the ventilation system from operating as designed.

What are the steps involved in testing the PCV valve?

High EGR flow results in undercalculation of the fuel and a lean air-fuel mixture, and low EGR flow drives the mixture rich.

Vacuum problems can be caused by incorrect hose routing or defects with a backpressure transducer, thermal switching valve, or solenoid.

The measurement 1 ppm means that out of every thousand parts of an exhaust sample, one part is HC.

How would you use a flowmeter to check for EVAP leaks?

Which of the following statements is LEAST-Likely true?

All of the following statements are true EXCEPT:

CO is oxidized into CO2 by the catalytic converter and ____________________ system.

A leaking or misplaced gasket to a valve cover or intake manifold can leak enough air to render the PCV system inoperable.

All of the following statements are true EXCEPT:

What are some of the possible causes of spark knock?

Introduction to the Automobile

Automotive Careers and Technician Certification

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Shop Management, Service Records, and Parts

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Brake Service

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A running engine will always have at least ____ CO₂.

CO is oxidized into CO₂ by the catalytic converter and ____________________ system.