Deck 38: Vehicle Emission Standards and Testing

Question 1

Technician A says that high HC emission levels are often caused by a fault in the ignition system. Technician B says that high CO₂emissions are usually caused by a richerthan- normal air-fuel mixture. Which technician is correct?

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

Answer 1

The high hydrocarbon (HC) emission levels are mostly caused by any sort fault in the specified ignition system. The high carbon dioxide
emission is usually caused by less rich than normal air-fuel mixture.
Thus, with reference to the above mentioned context, the technician A is correct while the statement of technician B is incorrect.
Hence, the correct option is
.

Question 2

List the five exhaust gases and their maximum allowable readings for a fuel-injected vehicle equipped with a catalytic converter.

Answer 2

The five exhaust gases and their corresponding maximum allowable readings for fuel-injected vehicles along with a catalytic converter are as follows:
1. Hydrocarbons
are unburned gasoline and are measured in ppm (parts per million). The acceptable level of hydrocarbon
is 50 PPM or less.
2. Carbon monoxide
is unstable and can be readily combined with any oxygen to form stable carbon dioxide
. The carbon monoxide
levels of a properly operating engine must be less than 0.5%.
3. Carbon dioxide
is due to the oxygen in the engine that combines with the carbon of the gasoline. The acceptable level of
lies between 12% to 15%. High reading indicates an efficiently operating engine.
4. Oxygen
is used during the combustion process to oxidize all the hydrogen and carbon (hydrocarbons) in the gasoline. The levels oxygen
should be low (about 0.5%). The level of oxygen
at idle is high due to an exhaust system leak.
5. Oxides of nitrogen
, the oxide of nitrogen
is a colorless, tasteless, and odorless gas when it leaves the engine. As it reaches the atmosphere and mixes with more oxygen, the nitrogen dioxide is formed. The acceptable level of oxides of nitrogen
, is 100 PPM or less at idle.

Question 3

HC and CO are high and CO₂and O₂are low. This could be caused by a _____________.

A) Rich mixture
B) Lean mixture
C) Defective ignition component
D) Clogged EGR passage

Answer 3

The following condition is caused by the rich mixture:
The rich mixture causes the hydrocarbon
and carbon monoxide
to be high and carbon dioxide
and oxygen
to be low.
Lean mixture, defective ignition component, and logged EGR system do not cause the hydrocarbon
and carbon monoxide
to be high and carbon dioxide
and oxygen
to be low. Hence, are not relevant to above mentioned context. Hence, options (b), (c), and (d) are not irrelevant to above mentioned context, hence are incorrect.
Hence, the correct option is
.

Question 4

List two causes of a rich exhaust.

Question 5

Which gas is generally considered to be the rich indicator? (The higher the level of this gas, the richer the air-fuel mixture.)

A) HC
B) CO
C) CO₂
D) O₂

Question 6

List two causes of a lean exhaust.

Question 7

Which gas is generally considered to be the lean indicator? (The higher the level of this gas, the leaner the air-fuel mixture.)

A) HC
B) CO
C) CO₂
D) O₂

Question 8

List those items that should be checked if a vehicle fails an exhaust test for excessive NO X emissions.

Question 9

Which exhaust gas indicates efficiency? (The higher the level of this gas, the more efficient the engine operates.)

A) HC
B) CO
C) CO₂
D) O₂

Question 10

All of the gases are measured in percentages except _____________.

A) HC
B) CO
C) CO₂
D) O₂

Question 11

After the following exhaust emissions were measured, how was the engine operating?
HC = 766 PPM CO₂= 8.2% CO = 4.6% O₂= 0.1%

A) Too rich
B) Too lean

Question 12

Technician A says that carbon inside the engine can cause excessive NO X to form. Technician B says that excessive NO X could be caused by a cooling system fault causing the engine to operate too hot. 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 13

A clogged EGR passage could cause excessive _____________ exhaust emissions.

A) HC
B) CO
C) NO X
D) CO₂

Question 14

An ignition fault could cause excessive _____________ exhaust emissions.

A) HC
B) CO
C) NO X
D) CO₂