Deck 44: Emission Control System Service

Question 1

A leaking EVAP system can allow gasoline vapors to escape into the air.

Answer 1

True

Question 2

While having a discussion, Technician A says that when analyzing exhaust readings CO and O₂ should be nearly equal. Technician B says that CO, O₂, and HC should be low. Who is correct?

A)A only
B)B only
C)Both A and B
D)Neither A nor B

Answer 2

C

Question 3

Which of the following statements is LEAST-Likely true?

A)NO_X emissions are highest at a point near stoichiometric.
B)NO_X 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 NO_X emissions are lower.

Answer 3

B

Question 4

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

Question 5

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:

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

Question 6

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

Question 7

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

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

Question 8

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

Question 9

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

Question 10

While having a discussion, Technician A says that driving the car on the road or on a dyno is the best way to heat up the cat. Technician B says that it is best to run the engine in a stall. Who is correct?

A)A only
B)B only
C)Neither A nor B
D)Both A and B

Question 11

The ____________________ analyzer measures the content of gases in the exhaust through a probe installed in the exhaust pipe of a running engine.

Question 12

A major cause of air pollution from motor vehicles is fuel ____________________.

Question 13

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

Question 14

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

Question 15

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

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

Question 16

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

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

Question 17

All of the following statements are true EXCEPT:

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 18

All of the following statements are true EXCEPT:

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 19

A running engine will always have at least ____ CO₂.

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

Question 20

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

Question 21

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

Question 22

What are some of the possible causes of spark knock?

Question 23

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

Question 24

How would you perform a snap test?

Question 25

What are the steps involved in testing the PCV valve?