Automotive Key Concepts

What modern day apparatus replaced carburetors about 40 years ago?

Electronic fuel injection; largely due to emissions control standards, the electronic fuel injection system is controlled by the PCM and incorporates feedback function that gives it flexibility to adjust to change engine conditions very quickly.

What is the framework in basic engine theory in which the cylinders are arranged?

Engine block

The high-voltage winding in a car's ignition system is called the _______

Secondary coil winding

In steering and suspension, what protects other car parts from the energy produced by the up-and-down movement of wheels?

Shock absorber

A two-stroke engine will normally be found on

Snowmobiles, chainsaws, lawn mowers, and some motorcycles need only two-stroke engines.

Define what a catalytic converter does

creates chemical reactions that makes toxic gas less toxic when exhausted from the vehicle's engine

When an engine continues to run after being turned off, it's called

dieseling

What allows the left and right wheels to turn at different speeds while cornering?

differential

_______ send data to a car's PCM; _________ receive commands from a car's computer

sensors; actuators

Describe camshaft arrangement differences; SOHC

single overhead cam; where only one camshaft is used to operate the intake and exhaust valves of a cylinder for an OHC. In a V-type engine with two cylinder heads, there would be two camshafts installed above each head.

The brushes in an alternator ride on

slip rings.

What parts have been eliminated in coil-on-plug ignition systems?

spark plug wires

Diesel engines lack a _____ (a common element in gasoline-burning engines).

spark-ignition system

How is the camshaft driven by the crankshaft?

timing belt or timing chain

What function does the distributor perform in the ignition system?

timing the ignition spark and DISTRIBUTING it to the correct cylinder

What is the basic function of a radiator do?

to transmit heat from the coolant to the outside atmosphere

What is the basic function of the chassis drivetrain system?

to transmit power from the engine to the wheels

TDC and BDC

top dead center and bottom dead center; travel from TDC to BDC and back constitutes one stroke.

What does an automatic transmission use instead of a clutch?

torque converter

A car equipped with limited-slip differential

transfers the most driving force to the wheel with the greatest amount of traction

The purpose of the driveshaft is to connect the

transmission to the differential

What component matches engine speeds to the desired speeds of the vehicle?

transmission; the workhorse of the drivetrain system powering the acceleration smoothly and quickly from the engine

What is the difference between disc brakes and drum brakes?

Disc brakes; where brake pads on both sides of a rotating disc are pinched together to slow the rotation of the disc Drum brakes; where brake shoes inside a rotating drum expand to make contact with the interior of the drum, slowing its motion.

Define PCM or ECU

Powertrain Control Module; Engine Control Unit this computer processes data from the sensors based on software (preprogrammed strategies) and then generates outputs to control vehicles functions.

Disc brakes work by:

Pressing inward on the disc, to stop from turning. The brake rotor (or disc) which rotates with the wheel, is clamped by brake pads (friction)that are fitted to the caliper from both sides with pressure from the piston(s) (pressure mechanism) and decelerates the disc rotation, thereby slowing down and stopping the vehicle.

Radiator caps have two valves; describe each

Pressure valve; as the engine warms, the coolant in the cooling system will expand, raising the overall pressure. When the psi exceeds the radiator cap, the pressure valve lifts, allowing some of the coolant to flow into the coolant reservoir bottle. The vacuum valve allows coolant to flow from the reservoir back into the radiator during cooldown.

The low-voltage winding in a car's ignition system is called _______

Primary coil winding

Describe what a catalytic converter does

Processes toxic waste gas from the engine's exhaust. It turns them into carbon dioxide, water, and other less harmful substances. Burning gasoline and/or diesel fuel creates harmful byproducts like nitrogen dioxide, carbon monoxide, hydrocarbons, benzene, & formaldehyde. In addition, vehicles emit carbon dioxide, the most common greenhouse gas

Define the viscosity of a liquid

Resistance to flow; liquids with a higher viscosity are thicker and flow less easily.

between the drive axle and the CV joints is a short drive shaft called the _______

half shaft; used mostly in front-wheel drive vehicles; they must be able to apply power to the drive wheels while allowing them to move up and down and turn the vehicle. There are two shafts, one for each drive wheel

When all other lights show normal illumination but one headlight is dim, it is a good sign that the

headlight has a poor ground connection.

Diesel engines (also known as compression-ignition engines) employ what to ignite the air/fuel mix?

high compression ratio

What is developed in the catalytic converter?

high heat, not toxic gas

What are the two advantages of a four-valve cylinder head over a two-valve cylinder head?

higher engine operating speeds; more complete combustion of the air-fuel mixture

What pressure do vehicle brakes work by?

hydraulic or fluid pressure

The most important property that enables a hydraulic brake system to transmit pressure from the master brake cylinder to all individual brakes if

incompressibility

Primary advantage for a V-shaped engine

inherent physical balance of the engine's moving components, resulting in a smooth-running engine. Another advantage is the decrease in height&weight as opposed to the inline engine. Also improves aerodynamics, the front of the car can be lower.

On older cars with carburetors, the air filter can be found

on top of the carburetor, on top of the engine on top

the camshaft turns at _____ the speed of the engine's crankshaft

one half

The terminals exposed on the ignition induction coil are

one secondary two primary On a conventional ignition coil, the center tower is the secondary or high-voltage terminal. The two small studs at the top of the coil are primary or low-voltage terminals.

Describe the function of a camshaft

opens and closes the cylinders' intake and exhaust valves in internal combustion engines

Describe camshaft arrangement differences; OHC

overhead cam; the camshaft is located above the valves and eliminates the pushrods. This operation is simpler and lighter, with less mass in the valve train means that higher engine speeds can be attained.

Describe camshaft arrangement differences; OHV

overhead valve; the camshaft is located in the engine block and intake/exhaust valves are located in the cylinder head (valves are located ABOVE the piston & combustion chamber) A lever called a rocker arm (operated by camshaft through pushrod) operates each valve. Can be used in either V-shaped or flat configuration engines.

The order in which an engine's spark plugs fire is established by the order in which the

plug leads are connected to the distributor cap.

Forcing unburned burned back into the cylinder so that it can be re-used is called

positive crank case ventilation

Define the term glazing

"using putty to hold glass to a window frame" a process that is used when replacing a pane of glass in a window frame

Cylinders _____ will fire on the _____ turn of the crankshaft, and subsequently _____ will fire on the _____ turn

1 & 3 on the first; 2 & 4 on the second

What are the four strokes of the four-stroke cycle from beginning to last?

1) Intake 2) Compression 3) Power 4) Exhaust

A common firing order for four-cylinder engines is

1, 3, 4, 2

Big block engines generally have more than _____ Liters of ________

5.9 L of displacement

What is the optimal psi range for a cooling system?

9-16 psi

Define cam belt

A cam belt, also known as a timing belt, connects the crankshaft to the cam shaft.

A clutch release bearing

A mechanical bearing within the clutch assembly that allows the clutch to disengage rotates whenever the clutch pedal is depressed.

In engine theory, what do piston rings function as?

A seal around the cylinder so that exhaust gases do not leak out and oil does not leak in.

Does a car's alternator produce DC or AC electricity?

AC

What happens in a vehicle's cylinder?

Air/fuel mixture is ignited, pushing the piston downward, and then exhaust gases are expelled when the piston moves upward.

Define how an induction clutch works

An induction clutch is a magnetic clutch. When a conductor (wire) is wrapped around a core and electricity is passed through the wire, it sets up a magnetic field.

Describe the two most common fuel injection system types; multiport injection

An injector for each cylinder, located in the intake manifold, with their spray directed toward the intake valves. As air is sucked into the intake manifold, it will flow all the way to the cylinder head before fuel in injected into it. This allows for a much better ratio and prevents fuel droplets from falling out on to the intake manifold runners.

Heat of compression ratio for diesel engines

Anywhere from 16:1 to 22:1

WHAT IS CHIEFLY RESPONSIBLE FOR GENERATING HYDRAULIC PRESSURE TO OPERATE A VEHICLE's BRAKES PROPERLY and SAFELY???

Brake Master Cylinder...

How does a vehicle's ABS work?

By adjusting the brake pressure in each wheel depending on that wheel's speed.

Why are automobile tires are black?

Carbon black is a byproduct of the combustion of various petroleum products. When added as a filler in rubber, it increases abrasion resistance and tensile strength. The stabilizing chemical, carbon black, makes car tires black.

Describe what a transaxle does

Combination of the transmission and drive axle. These two components are normally two separate components in rear wheel drive vehicles.has several "gear" that are selected according to the speed of the vehicle and how fast the driver wants to accelerate.

Describe what a connecting rod does

Connect each piston to the crankshaft

In engine theory, what does a crankshaft do?

Converts the linear motion of the piston into rotary motion. A good analogy is someone riding and a bike - the piston-rod-crankshaft theory can be seen as the rider's upper leg moving up and down (pistons), while the lower leg (connecting rod) combined with the pedals and sprocket (crankshaft) turn linear energy into rotary energy, driving the bike forward.

Describe the stage that radiator hoses are utilized

Coolant flowing through the radiator to the engine and returning from the engine to the radiator

Does a car's battery provide DC or AC electricity?

DC

Describe what a fuel rail does

Delivers fuel under pressure to the engine's fuel injectors

An engine's rotational energy is stored by using which mechanical device?

Flywheel

Describe the function of a cylinder

Forms a guide for the piston, allowing the piston to move up and down as the engine completes its cycle

Describe the exhaust stroke

Gases in the combustion chamber (area created in cylinder head above piston) are now spent and must be purged from the engine before the next cycle can begin. As the piston begins upward movement towards TDC again, it pushes waste gas through the open exhaust valve and into the engine's exhaust system. The piston continues traveling upward. Once at TDC, intake begins and the four-stroke cycle begins again.

Describe the two most common fuel injection system types; direct fuel injection

High-pressure fuel injector sprays highly pressurized fuel directly into the combustion chamber. Therefore, only air flow over the intake valves and enters the chamber as well. Fuel can then be sprayed at an optimized point in the compression stroke. This also allows the fuel to act as a coolant to the hot compressed air in the combustion chamber, allowing the engine to be designed with further degrees of compression, increasing power, strength, and efficiency (big trucks, mowers, semis, etc....)

Why is a coolant recovery reservoir necessary?

In order to capture overflow when the radiator pressure cap valve opens, because the flow of coolant between the engine and radiator varies based on the heat of the engine

universal joints

Like CV joints, universal joints (U-joints) are located at each end of a drive shaft and allow the shaft to operate at a variable angle with the component that it is driving. Universal joints perform the same basic function as CV joints but CV joints have a wider range of operation.

Describe what water jackets do

Like oil galleries, they are drillings of hollow sections in the engine block through which coolant flows.

Describe what happens in the engine's oil pan?

Oil drips from various engine parts into the pan, cools down, and is picked up by the oil tube and sent back to oil pump.

Describe what oil galleries are

Oil galleries are drilled compartments within an engine assembly that delivers oil to critical components of the engine.

How is a vehicle's oil pump powered?

Oil pumps are usually either inside the oil pan and driven by a camshaft, or outside the pan and driven by a crankshaft

Internal combustion engines take ____ energy, convert it into ____ energy, and then finally into ____ energy.

Take chemical energy, turn it into heat energy, finally creating mechanical energy

Which component allows the left and right wheels to turn at different speeds when cornering?

The differential lets wheels turn at different rates. When one tire is spinning, the other can have traction.

What are two main components of engine oil?

base oil and additive package

Stoichiometric ratio for typical gasoline engines

The ideal ratio of air to fuel into the engine cylinder is 14.7:1

Which is considered the left side of an engine?

The left side when you sit in the driver's seat and face forward

Describe an oil filters path

The oil filter filters the oil after it leaves the oil pump, and before it circulates through the engine

Describe what a piston does

The piston is a cylindrical object that moves up and down inside a cylinder Pistons work by transferring the force output of expanding gas in the cylinder to a crankshaft, which provides rotational momentum to a flywheel. Such a system is known as a reciprocating engine.

Describe the compression stroke

The piston starts to move from BDC to TDC and both of the cylinder valves are closed. This upward stroke and sealed combustion chamber create a high-pressure are of air/fuel. This reaction causes the mixture to become hotter and therefore easier to ignite, causing the power of the next stroke (power). The piston is almost at TDC, but the spark plug fires and ignites the air/fuel mixture, sparking a flame across the entire combustion chamber. This flamer further heats the gas, resulting in rapid expansion of these gases pushing on the piston as it reached TDC, causing the power stroke

Drum brakes work by:

The pistons press the brake linings (friction), against the inside surfaces of the brake drums, which rotate with the wheels. The linings are pressed on the rotating drums, which in turn decelerate the wheels, thereby slowing down and stopping the vehicle.

Describe the power stroke

This stroke ensures that the pressure generated from the combustion does not blow past either valve, so both the cylinder valves remain closed, and before the piston reaches BDC, combustion of the air/fuel mixture should be completed. Just before reaching BDC, energy is extracted from the piston pushing downward and the exhaust begins to open and the engine begins the final stroke, exhausting the waste gases.

What do the constant velocity joints in a drivetrain system do?

Transmit power through very steep angles in order to transfer mechanical energy to the vehicle's wheels

Describe the intake stroke

When the pistons goes from TDC to BDC to take in air. This downward stroke forms a low-pressure area (vacuum). As the air travels into the cylinder, fuel is injected into the air stream before entering the combustion chamber. Once the piston is at BDC, and a fresh mixture of air and fuel is in the cylinder, and the intake valve is almost closed again, compression begins

Air fuel ratio

a comparison of the weight of the air relative to the weight of the fuel that has been mixed with it. ideal air-Fuel ratio is 14.7: 1

Define what a carburetor does

a device that blends air and fuel for most older cars (pre-1990). As air moves quickly through the _____, it creates a vacuum, which draws more and more fuel into the mixture

V-6 engine

a six-cylinder piston-engine where the cylinders share a common crankshaft and are arranged in a V configuration. Due to their short length, V-6 engines are often used as the larger engine option for vehicles which are otherwise produced with inline-four engines, especially in transverse engine vehicles

If a car's ignition system, lights, and radio don't work, the part that's probably malfunctioned is the

battery

Coolant is circulated throughout the radiator and engine block by the

belt- or timing-chain-driven water pump. The engine crankshaft drives the belt, so the water pump actually uses engine power to operate

Describe what an intake manifold does

a structure that delivers air to the intake valves of the engine's cylinders

25 degrees BTDC (before top dead center) is an example of ________ ignition timing.

advanced ignition timing

What are two major types of cooling systems?

air-cooling and water-cooling air-cooling circulates hot air of cooling fins on the outside of the engine to remove heat. water-cooling uses liquid coolant (ethylene glycol) ro pick up excess heat and then rejects that heat through a radiator. Cylinder temps need to quickly reach operating temp and remain consistent throughout a wide range of ambient temps. Favored due to its flexibility in coolant circuit design, heat transfer ability, and high heat capacity.

Describe the function of the intake valve

allows the air-fuel mixture to be drawn into the combustion chamber

What term refers to the rebuilding of an engine to precise, exact factory specs?

blueprinting

What is the main component of the charging system and converts mechanical energy into electrical energy?

alternator

V-8 engine

an eight-cylinder piston-engine in which [two banks] of [four cylinders] share a common crankshaft and are arranged in a V configuration.

A symptom of worn piston rings would be

an engine using excessive amounts of oil

inline engines; all of the engine's cylinders (practical design for four- and six- cylinder engines)

are lined up in a row. Inline four cylinders are very popular with in FWD cars with transverse (sideways) mounted engines

In suspension and steering systems, describe what ball joints do

ball-and-socket arrangements that allow the steering knuckle to turn and move up and down

How do shock absorbers dissipate suspension system energy

by converting motion energy into heat energy

constant-velocity joints

can transmit power through very steep grades and angles, and are located at each end of a half shaft. The inboard CV joint is located on the transaxle, and the outboard CV joint is located behind the vehicle wheel

Coil on plug ignition system

coil on plug (COP) ignition is a system where an individual ignition coil is placed on top of spark plug, found on the head of the cylinder and separating coils from exhaust heat. This makes it easier for spark plugs to receive voltage. eliminates the need for spark plug wires

The transaxle in a front-wheel drive vehicle combines which two components that are normally distinct in a rear-wheel drive vehicle?

combines the transmission and the drive axle

A two-stroke engine completes a power cycle with __#__ strokes of the piston during one power cycle, completed in __#__ revolution of the __________.

completes a power cycle with 2 strokes of the piston during one power cycle, completed in 1 revolution of the crankshaft.

In a three-speed transmission, the cluster gear is supported by the

countershaft

Describe camshaft arrangement differences; DOHC

double overhead camshaft; when even higher engine speeds want to be achieves, two camshafts are installed into each of the cylinder heads, allowing one camshaft to operate each valve independently in a given head. DOHC eliminates the rocker arms that are often used in SOHC engines.

Describe what happens in detonation of an air-fuel mixture exploding rather than burning evenly

driver will hear a "knock"; happens with lean mixture (too much air, not enough fuel) that takes too long to burn. As the flames moves across the combustion chamber, the unburnt gasoline ignites. Two flame fronts collide and a pressure spike from this abnormal combustion results in a brutal shock to the engine's assembly. Severe damage occurs

If the engine oil appears milky, what is the probable cause?

engine chamber, oil mixing with moisture

spent fuel gases exit the cylinder and pass into what?

exhaust manifold

The crankshaft typically connects to a

flywheel [The crankshaft is connected to the flywheel, which causes it to rotate, operating the pistons.]

most internal combustion engines employ a ______-stroke cycle

four

Vapor locking in an automobile's brake system is caused by?

frequent braking

If the steering wheel vibrates at high speeds, the most likely problem is

front tires need balancing, or a bent rim

What are two likely causes of a pre-ignition?

glowing spark plug, or hot piece of carbon

What are three most common cylinder arrangements in internal combustion engines?

inline horizontally opposed (flat) V-type

Multiport fuel injectors are located in

intake manifold, not throttle body

Car batteries have plates from ____ immersed in a mixture of _______ ____ & ______

lead, sulfuric acid; water

Too much air, not enough fuel

lean mixture

Transfer case

located between the transmission and the drive axles on a four wheel drive vehicle The transfer case splits the engines power between the front and rear drive axle

drive shaft

longer version of half-shaft, the drive shaft transmits torque from the transmission to the drive axle; required to allow up and down movement of the vehicle's wheels, but not the same extent as the half-shaft in a front-wheel drive

The general procedure to follow when adjusting a band on an automatic transmission is to

loosen, tighten to a specified torque, loosen a specified number of turns, and lock.

Five functions that an engine's lubrication system performs

lubes, cools, seals, cleans, and quiets. Reduces friction

horizontally opposed (flat) engines; all of the engine's cylinders

lying in a horizontal plane, with half of the cylinders facing away from the other half and the crankshaft located between them

Alternators convert ____ energy to _____ energy

mechanical energy (rotary motion) into electrical energy (output current).

Exhaust gases pass from the catalytic converter through the ____ before hitting the atmosphere

muffler

Cross-plane crankshaft

produces less vibration in V-8's due to the perfect primary and secondary balance. The cross-plane crankshaft has the four crank pins (numbered from the front) at angles of 0, 90, 180, and 270 degrees, which results in a cross shape for the crankshaft when it is viewed from one end.

An overhead valve engine is also called a

pushrod engine [An overhead valve (OHV) engine uses pushrods to move the rocker arms above the cylinder head to actuate the valves. It places the camshaft within the cylinder block using pistons.]

The proportioning valve in a hydraulic brake system

reduces pressure to the rear brakes.

Too much fuel, not enough air

rich mixture

a 12:1 fuel mixture would be

rich, not lean. More fuel than average 14.7:1

The primary purpose of the piston rings is to

seal the combustion chamber and allow the pistons to move freely Piston rings are seals that keep the exploding gases in the combustion chamber.

Hydraulic fluid is transported to each individual brake by

the brake lines

If air gets into the hydraulic brake system

the brake pedal action will be spongy

Oil galleries in the crank shaft provide pressurized oil to

the connecting rod bearings

A primary advantage of the electronic ignition system over conventional ignition systems is that

the electronic ignition system requires a lower voltage to provide a higher voltage

In terms of lubrication, what area of the vehicle system is most critical?

the engine's reciprocating assembly, i.e., the pistons, the connecting rods, and the crankshaft, in order to reduce friction and to remove heat

During the compression stroke on a four-cycle engine:

the intake valve closes, and the piston moves to the top of the cylinder

The alternating current produced by the vehicle's alternator is converted to direct current by what?

the rectifier (or rectifier bridge)

Coolant does not pass through the radiator when

the thermostat is closed (the engine is below operating temperature)

V-type engines; cylinder set up (most popular for six- and eight-cylinder engines)

these engines have one crankshaft connected to the pistons on both sides of the engine. The two rows are located 60 to 90 degrees from each other (thus the V-shape). Each row has one cylinder head, for a total of two heads for the engine.

drive axle

transmits engine power through a 90° angle, and splits the power between the two drive wheels. The wheels are attached to the end of the drive axle, and the drive axle incorporates a differential, which allows the left and right wheels to turn at different speeds while turning

Describe what a clutch does

transmits torque from the engine to the transmission

Describe multiple-valve cylinder heads; two- and four-valve cylinder head arrangements

two-valve cylinder; one intake and one exhaust valve per cylinder four-valve cylinder; two intake and two exhaust valves per cylinder (V-8 will fire cylinders 1, 8, 4, 3 on the first turn of crankshaft, subsequently 6, 5, 7, and 2 on the second turn)

The iconic rumbling exhaust sound produced by a typical cross-plane V8 engine is partly due to the

uneven firing order within each of the two banks of four cylinders. A typical firing order results in uneven intake and exhaust pulse spacing for each bank. When separate exhaust systems are used for each bank of cylinders, this uneven pulsing results in the rumbling sound that is typically associated with V8 engines fun fact: Racing engines seek to avoid these uneven exhaust pressure pulses, to maximize the power output. The 1960s cross-plane V8 racing engines used long primary exhaust pipes (such as the Ford GT40 endurance racing car) or located the exhaust ports on the inside of the V-angle (such as the Lotus 38 IndyCar) to link the exhaust systems from each bank and provide even exhaust gas pulses)

When a driver turns on the car's lights or radio, this causes a decrease in system voltage. What component responds to this by increasing the output of the alternator?

voltage regulator