CEI Fuel Systems & Engine Combustion Flashcards
6 cards from real CEI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CEI Fuel Systems & Engine Combustion flashcards as text
Which combustion byproduct is formed when carbon-based fuels burn incompletely due to insufficient oxygen?
Answer: Carbon monoxide (CO)
Carbon monoxide (CO) is produced during incomplete combustion when there is insufficient oxygen to fully oxidize carbon to CO2.
What is the stoichiometric air-to-fuel ratio for a gasoline-powered internal combustion engine?
Answer: 14.7:1 (14.7 parts air to 1 part fuel by mass)
The stoichiometric air-to-fuel ratio for gasoline is 14.7:1, meaning 14.7 grams of air are required to completely combust 1 gram of gasoline with no excess oxygen or unburned fuel.
How do oxides of nitrogen (NOx) primarily form during internal combustion engine operation?
Answer: At high combustion temperatures, atmospheric nitrogen reacts with oxygen inside the combustion chamber
NOx forms primarily through the thermal Zeldovich mechanism, where the high temperatures in the combustion chamber (above ~1,300°C) cause atmospheric nitrogen and oxygen to react.
What does a rich air-fuel mixture (lambda < 1) typically produce in excess in vehicle exhaust compared to a stoichiometric mixture?
Answer: Higher CO and HC emissions due to incomplete combustion from excess fuel
A rich mixture (excess fuel) leads to incomplete combustion, producing elevated CO and unburned hydrocarbon (HC) emissions because there is insufficient oxygen to fully oxidize all the fuel.
Which fuel system component is responsible for atomizing and injecting precise amounts of fuel into the engine's intake ports or combustion chamber?
Answer: Fuel injector
Fuel injectors are electronically controlled solenoid valves that atomize and deliver precise quantities of fuel into the intake port or directly into the combustion chamber based on ECU commands.
What is the role of the exhaust gas recirculation (EGR) system in reducing vehicle emissions?
Answer: It recirculates a portion of exhaust gases back into the intake to lower peak combustion temperatures, reducing NOx formation
The EGR system dilutes the intake charge with inert exhaust gases, lowering peak combustion temperatures and oxygen concentration, which reduces the thermal formation of NOx.