Question 1

Compression ratio

Accepted Answer

The ratio of the volume of the combustion chamber at its largest to the volume at its smallest.

Question 2

Glow plugs

Accepted Answer

Electric heating elements used to aid in cold starting of diesel engines.

Question 3

Direct injection

Accepted Answer

Fuel injection system in which fuel is injected directly into the combustion chamber.

Question 4

EGR (Exhaust Gas Recirculation)

Accepted Answer

System that recirculates a portion of the exhaust gases back into the engine for emission control.

Question 5

Common rail

Accepted Answer

Fuel injection system that uses a high-pressure common rail to deliver fuel to individual injectors.

Question 6

Turbocharger

Accepted Answer

Forced induction device that increases an engine's efficiency and power by compressing the incoming air.

Question 7

Intercooler

Accepted Answer

Heat exchanger used to cool the compressed air from the turbocharger before it enters the engine.

Question 8

EGT (Exhaust Gas Temperature)

Accepted Answer

Measurement of the temperature of the exhaust gases leaving the engine.

Question 9

DPF (Diesel Particulate Filter)

Accepted Answer

Device that captures and removes particulate matter (soot) from the diesel exhaust.

Question 10

SCR (Selective Catalytic Reduction)

Accepted Answer

Aftertreatment system that uses a catalyst and a urea-based solution (DEF) to reduce nitrogen oxide (NOx) emissions.

Question 11

DEF (Diesel Exhaust Fluid)

Accepted Answer

Urea-based solution used in conjunction with SCR systems to reduce NOx emissions.

Question 12

Injector timing

Accepted Answer

The precise timing at which fuel is injected into the combustion chamber.

Question 13

Injection pump

Accepted Answer

Device that pressurizes and delivers fuel to the injectors in a diesel engine.

Question 14

Fuel system priming

Accepted Answer

Process of removing air from the fuel system and ensuring the delivery of fuel to the injectors.

Question 15

Injection pressure

Accepted Answer

The pressure at which fuel is injected into the combustion chamber.

Question 16

Engine brake

Accepted Answer

System that uses engine compression to slow down a vehicle, reducing the wear on the service brakes.

Question 17

Compression release brake

Accepted Answer

Valve mechanism that releases compression in the cylinders to aid in slowing down the vehicle.

Question 18

Camshaft

Accepted Answer

Rotating shaft with lobes that open and close the engine's valves.

Question 19

Crankshaft

Accepted Answer

Shaft that converts reciprocating motion into rotational motion in an engine.

Question 20

Connecting rod

Accepted Answer

Component that connects the piston to the crankshaft in an engine.

Question 21

Piston rings

Accepted Answer

Sealing rings that prevent combustion gases from escaping the combustion chamber.

Question 22

Piston pin

Accepted Answer

Connecting component between the piston and connecting rod in an engine.

Question 23

Cylinder head

Accepted Answer

Component that covers the top of the cylinder block and houses the valves and other engine components.

Question 24

Valve timing

Accepted Answer

The precise timing at which the engine's valves open and close.

Question 25

Intake manifold

Accepted Answer

Component that distributes air to the engine's cylinders.

Question 26

Exhaust manifold

Accepted Answer

Component that collects and directs exhaust gases away from the engine.

Question 27

Valve clearance

Accepted Answer

The gap between the valve stem and the rocker arm or camshaft.

Question 28

Valve lash

Accepted Answer

The clearance or gap between the valve stem and the rocker arm or lifter.

Question 29

Valve stem seals

Accepted Answer

Sealing rings that prevent oil from entering the combustion chamber through the valve guides.

Question 30

Valve spring

Accepted Answer

Spring that closes the engine's valves after they have been opened.

Question 31

Valve lift

Accepted Answer

The maximum distance the valve opens during each cycle.

Question 32

Compression test

Accepted Answer

Test to measure the compression pressure in each cylinder.

Question 33

Leak-down test

Accepted Answer

Test to determine the amount of leakage in an engine's cylinders.

Question 34

Cylinder pressure waveform

Accepted Answer

Graphical representation of the pressure changes inside the cylinder during the four-stroke cycle.

Question 35

Fuel viscosity

Accepted Answer

Measure of the thickness or flow characteristics of diesel fuel.

Question 36

Fuel filter

Accepted Answer

Component that removes impurities and contaminants from the fuel before it reaches the injectors.

Question 37

Fuel water separator

Accepted Answer

Device that separates water and contaminants from the fuel to prevent damage to the fuel system.

Question 38

Injection nozzle

Accepted Answer

Component that delivers fuel into the combustion chamber in a diesel engine.

Question 39

Injection timing

Accepted Answer

The precise timing at which fuel is injected into the combustion chamber.

Question 40

Cylinder bore

Accepted Answer

The diameter of the cylinder in an engine.

Question 41

Piston skirt

Accepted Answer

The lower part of the piston that contacts the cylinder wall.

Question 42

Oil pump

Accepted Answer

Device that circulates oil through the engine to lubricate moving parts.

Question 43

Oil filter

Accepted Answer

Component that removes contaminants from the oil to protect the engine.

Question 44

Crankcase ventilation system

Accepted Answer

System that removes blow-by gases from the crankcase and prevents oil contamination.

Question 45

Timing belt

Accepted Answer

Belt that synchronizes the rotation of the crankshaft and camshaft in an engine.

Question 46

Timing chain

Accepted Answer

Chain that synchronizes the rotation of the crankshaft and camshaft in an engine.

Question 47

Camshaft position sensor

Accepted Answer

Sensor that detects the position of the camshaft for proper fuel injection timing.

Question 48

Crankshaft position sensor

Accepted Answer

Sensor that detects the position of the crankshaft for ignition timing and fuel injection.

Question 49

Engine control module (ECM)

Accepted Answer

Electronic control unit that manages the engine's operation and performance.

Question 50

Air filter

Accepted Answer

Component that removes dust and debris from the intake air before it enters the engine.

Question 51

Mass airflow sensor (MAF)

Accepted Answer

Sensor that measures the amount of air entering the engine for fuel control.

Question 52

Throttle position sensor (TPS)

Accepted Answer

Sensor that detects the position of the throttle plate for engine management.

Question 53

EGR valve

Accepted Answer

Valve that controls the flow of exhaust gases into the intake manifold for emission control.

Question 54

Variable geometry turbocharger (VGT)

Accepted Answer

Turbocharger with adjustable vanes for optimal boost control.

Question 55

Fuel pressure regulator

Accepted Answer

Component that maintains a consistent fuel pressure for proper fuel delivery.

Question 56

Fuel rail

Accepted Answer

Component that distributes fuel to the injectors in a common rail system.

Question 57

Fuel pump

Accepted Answer

Device that delivers fuel from the tank to the fuel system.

Question 58

Camshaft sensor

Accepted Answer

Sensor that detects the position and speed of the camshaft for engine management.

Question 59

Crankshaft sensor

Accepted Answer

Sensor that detects the position and speed of the crankshaft for engine management.

Question 60

Knock sensor

Accepted Answer

Sensor that detects abnormal combustion (knocking) and adjusts ignition timing to prevent engine damage.

Question 61

Torque converter

Accepted Answer

Fluid coupling device that transmits engine power to the transmission in an automatic transmission vehicle.

Question 62

Diesel fuel additives

Accepted Answer

Chemical substances added to diesel fuel to improve performance, lubrication, and reduce emissions.

Question 63

Valve clearance adjustment

Accepted Answer

Process of adjusting the gap between the valve stem and the rocker arm or camshaft.

Question 64

Overhead camshaft (OHC)

Accepted Answer

Camshaft located above the cylinder head, operating the valves directly.

ASE A9 Certification Flashcards - Light Vehicle Diesel Engines