CEI CEI Fuel Systems & Engine Combustion

Question 1

Which combustion byproduct is formed when carbon-based fuels burn incompletely due to insufficient oxygen?

Accepted Answer

Carbon monoxide (CO)

Answer

Carbon dioxide (CO2)

Answer

Nitrogen gas (N2)

Answer

Water vapor (H2O)

Question 2

What is the stoichiometric air-to-fuel ratio for a gasoline-powered internal combustion engine?

Accepted Answer

14.7:1 (14.7 parts air to 1 part fuel by mass)

Answer

10.5:1 (10.5 parts air to 1 part fuel by mass)

Answer

17.0:1 (17.0 parts air to 1 part fuel by mass)

Answer

21.0:1 (21.0 parts air to 1 part fuel by mass)

Question 3

How do oxides of nitrogen (NOx) primarily form during internal combustion engine operation?

Accepted Answer

At high combustion temperatures, atmospheric nitrogen reacts with oxygen inside the combustion chamber

Answer

From sulfur impurities in diesel fuel reacting with oxygen

Answer

From the decomposition of nitrogen-containing fuel additives at low temperatures

Answer

From the catalytic converter oxidizing nitrogen in the exhaust stream

Question 4

What does a rich air-fuel mixture (lambda < 1) typically produce in excess in vehicle exhaust compared to a stoichiometric mixture?

Accepted Answer

Higher CO and HC emissions due to incomplete combustion from excess fuel

Answer

Higher NOx emissions due to increased combustion temperatures

Answer

Higher CO2 emissions with no change in HC levels

Answer

Lower CO and HC emissions because more fuel is burned completely

Question 5

Which fuel system component is responsible for atomizing and injecting precise amounts of fuel into the engine's intake ports or combustion chamber?

Accepted Answer

Fuel injector

Answer

Fuel pressure regulator

Answer

Mass airflow sensor

Answer

Throttle position sensor

Question 6

What is the role of the exhaust gas recirculation (EGR) system in reducing vehicle emissions?

Accepted Answer

It recirculates a portion of exhaust gases back into the intake to lower peak combustion temperatures, reducing NOx formation

Answer

It recirculates exhaust gases to increase fuel atomization and reduce HC emissions

Answer

It captures unburned hydrocarbons in the exhaust and returns them to the fuel tank

Answer

It lowers CO emissions by injecting fresh oxygen into the exhaust stream