Question 1

How many degrees of crankshaft rotation does it take to complete one complete engine cycle in a 4-stroke engine?

Accepted Answer

A 4-stroke engine requires two complete revolutions of the crankshaft to complete one engine cycle, which equals 720 degrees.

Question 2

What type of ICE engine listed below is commonly found in a hybrid vehicle?

Accepted Answer

The Atkinson-cycle engine is commonly found in hybrid vehicles because it is designed to be more efficient at the cost of some power output, which is compensated for by the electric motor in a hybrid system.

Question 3

The reciprocating movement of the piston is converted into rotary motion by the _____.

Accepted Answer

The crankshaft and connecting rod mechanism is responsible for converting the reciprocating (up-and-down) motion of the piston into rotary motion, which is then used to drive the vehicle's wheels or operate other machinery.

Question 4

A four-stroke cycle engine requires at least _____ valves at the top of each cylinder.

Accepted Answer

A four-stroke cycle engine requires at least two valves at the top of each cylinder: one for the intake of air (and possibly fuel) and one for the exhaust to exit.

Question 5

Which V-type engine valve train design may use four camshafts?

Accepted Answer

DOHC (Dual Overhead Camshaft) engines can use four camshafts, with two camshafts per cylinder bank in a V-type engine configuration, allowing for precise valve timing and high performance.

Question 6

Diesel engines are being discussed. Technician A says diesel engines have a distributor-type injection pump. Technician B says diesel engines have a common fuel rail and the injectors are controlled by the computer. Who is correct?

Accepted Answer

Diesel engines can use both types of systems for fuel injection. Older diesel engines often use a distributor-type injection pump, while modern diesel engines frequently use a common rail system where the injectors are electronically controlled by a computer.

Question 7

Engine oil pressure testing is being discussed. Technician A says that oil pressure should be tested with the engine cold. Technician B says oil with viscosity that is too high may cause lower than specified pressure. Who is correct?

Accepted Answer

The answer of Engine oil pressure testing is being discussed....

Question 8

Technician A says the engine displacement can be found on the engine ID tag. Technician B says the date the engine was assembled can be found in the casting numbers on the cylinder block. Who is correct?

Accepted Answer

The answer of Technician A says the engine displacement can...

Question 9

Two technicians are discussing diesel engines. Technician A says all diesel engines are fuel injected. Technician B says glow plugs help ignite the fuel when the engine is cold. Who is correct?

Accepted Answer

Both statements are correct. All diesel engines use fuel injection for their operation, and glow plugs are indeed used to help ignite the fuel in diesel engines when they are cold.

Question 10

A wet compression test is performed on an engine after a dry compression test revealed low compression on one cylinder. If the compression on the low cylinder rises, it indicates _____.

Accepted Answer

When a wet compression test (adding a small amount of oil to the cylinder) results in higher compression compared to a dry test, it typically indicates worn piston rings. The oil temporarily seals the gaps between the worn rings and the cylinder wall, improving compression.

Question 11

The ____________________ controls the movement of the valves.

Accepted Answer

The answer of The ____________________ controls the movement of the...

Question 12

Technician A says weak valve springs can be detected with a vacuum test. Technician B says a restricted exhaust can be detected with a vacuum test. Who is correct?

Accepted Answer

Both weak valve springs and a restricted exhaust can indeed be detected with a vacuum test. Weak valve springs can cause fluctuations in vacuum readings, while a restricted exhaust can lead to a decrease in vacuum levels.

Question 13

Technician A says engine displacement is commonly measured in cubic millimeters. Technician B says it is commonly measured in cubic inches. Who is correct?

Accepted Answer

Engine displacement is commonly measured in cubic inches in the United States and in liters (which can be converted to cubic centimeters, not millimeters) in most other parts of the world.

Question 14

Front engine, longitudinal layout is being discussed. Technician A says this layout is used in rear-wheel drive vehicles. Technician B says this layout is used in some front-wheel drive vehicles. Who is correct?

Accepted Answer

Both Technician A and Technician B are correct. The front engine, longitudinal layout is commonly used in rear-wheel drive vehicles for better weight distribution and handling. However, it is also used in some front-wheel drive vehicles, particularly in larger cars or those designed for specific performance or packaging needs.

Question 15

In what type of engine is the intake valve held open longer than normal during the compression stroke?

Accepted Answer

The Atkinson cycle engine holds the intake valve open longer than normal during the compression stroke to allow a part of the air-fuel mixture back into the intake manifold. This process effectively reduces the compression ratio without changing the expansion ratio, improving fuel efficiency.

Question 16

The largest part of the engine is the ____________________.

Accepted Answer

The answer of The largest part of the engine is...

Question 17

What component of the engine determines the stroke?

Accepted Answer

The crankshaft determines the stroke in an engine because it converts the linear motion of the pistons into rotational motion, and its design dictates the distance the piston travels in the cylinder, which is the stroke.

Question 18

Both valves are closed on the _____ strokes.

Accepted Answer

During the compression and power strokes, both valves are closed to allow the piston to compress the air-fuel mixture and then to contain the explosion for maximum power output.

Question 19

Two technicians are discussing compression testing on a hybrid vehicle equipped with an Atkinson cycle engine. Technician A says the compression reading of an Atkinson cycle engine is normally higher than a conventional engine. Technician B says a scan tool may be needed to perform the compression test. Who is correct?

Accepted Answer

Technician B is correct because, in modern vehicles, especially hybrids with Atkinson cycle engines, a scan tool may be required to properly perform a compression test due to the engine's advanced control systems. Technician A is incorrect because Atkinson cycle engines typically have lower compression readings than conventional engines due to their design, which allows the intake valve to stay open longer, effectively reducing compression ratio for efficiency gains.

Question 20

How can cam timing be checked?

Accepted Answer

Cam timing can be checked using a lab scope to analyze the camshaft sensor's signal and by checking the timing marks on the camshaft and corresponding components to ensure they are aligned properly.

Quiz 9: Automotive Engine Designs and Diagnosis