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Parent Category: Maintenance Guide

Category: Engine Guide

Automotive terms Modern (F)

Automotive Technical terms and abbreviations overview used in the industry, Guide and explanations.

The following are examples of Mid Modern technical terms F recommended for general use worldwide. For in-depth specific terms also see terms for historic vintage and specific areas such as Paint.

FAIL-SAFE (BACKUP) CONTROL:
A substitute value used by the PCMT to replace a faulty signal from an input sensor. The temporary value allows the vehicle to continue to be operated.

FAST IDLE:
The Speed Of the engine When the Choke is on. Fast idle

FEEDBACK:
A circuit malfunction whereby current can find another

FEELER GAUGE:
A blade, usually metal, of precisely predetermined thickness, used to measure the clearance between two parts.

FILAMENT:
The part of a bulb that glows; the filament creates high resistance to current flow and actually glows from the resulting heat.

FINAL DRIVE:
An essential part of the axle drive assembly where final gear reduction takes place in the powertrain. In RWD applications and north-south FWD applications, it must also change the power flow direction to the axle shaft by ninety degrees. (Also see axle ratio).

FIRING ORDER:
The order in which combustion occurs in the cylinders of an engine. Also the order in which spark is distributed to the plugs

FIRM:
A noticeable quick apply of a clutch or band that is considered normal with medium to heavy throttle shift; should not be confused with harsh or rough.

FLAME FRONT:
The term used to describe certain aspects of the fuel explosion in the cylinders. The flame front should move in a controlled pattern across the cylinder, rather than simply exploding immediately.

FLARE (SLIPPING):
A quick increase in engine rpm accompanied by momentary loss of torque; generally occurs during shift.

FLAT ENGINE:
Engine design in which the pistons are horizontally opposed. Porsche, Subaru and some old VW are common examples of flat engines.

FLAT RATE:
A dealership term referring to the amount of money paid to a technician for a repair or diagnostic service based on that particular service versus dealership's labor time (NOT based on the actual time the technician spent on the job).

FLAT SPOT:
A point during acceleration when the engine seems to lose power for an instant.

FLOODING:
The presence of too much fuel in the intake manifold and combustion chamber which prevents the air/fuel mixture from firing, thereby causing a no-start situation.

FLUID:
A fluid can be either liquid or gas. In hydraulics, a liquid is used for transmitting force or motion.

FLUID COUPLING:
The simplest form of hydrodynamic drive, the fluid coupling consists of two look-alike members with straight radial varies referred to as the impeller (pump) and the turbine. Input torque is always equal to the output torque.

FLUID DRIVE:
Either a fluid coupling or a fluid torque converter. (See hydrodynamic drive units.)

FLUID TORQUE CONVERTER:
A hydrodynamic drive that has the ability to act both as a torque multiplier and fluid coupling. (See hydrody-
namic drive units; torque converter.)

FLUID VISCOSITY:
The resistance of a liquid to flow. A cold fluid (oil) has greater viscosity and flows more slowly than a hot fluid (oil).

FLYWHEEL:
A heavy disc of metal attached to the rear of the crankshaft. It smoothes the firing impulses of the engine and keeps the crankshaft turning during periods when no firing takes place. The starter also engages the flywheel to start the engine.

FOOT POUND
(ft. lbs., lbs. ft. or sometimes, ft. lb.): The amount of energy or work needed to raise an item weighing one pound, a distance of one foot.

FREEZE PLUG:
A plug in the engine block which will be pushed out if the coolant freezes, Sometimes called expansion plugs, they protect the block from cracking should the coolant freeze.

FRICTION:
The resistance that occurs between contacting surfaces. This relationship is expressed by a ratio called the coefficient of friction

FRICTION, COEFFICIENT OF:
The amount of surface tension between two contacting surfaces; expressed by a scientifically calculated number.

FRONT END ALIGNMENT:
A service to set caster, camber and toe-in to the correct specifications, This will ensure that the car steers and handles properly and that the tires wear properly.

FRICTION MODIFIER:
Changes the coefficient of friction of the fluid between the mating steel and composition clutch/band surfaces during the engagement process and allows for a certain amount of intentional slipping for a good "shift-feel".

FRONTAL AREA:
The total frontal area of a vehicle exposed to air flow.

FUEL FILTER:
A component of the fuel system containing a porous paper element used to prevent any impurities from entering the engine through the fuel system. It usually takes the form of a canister-like housing, mounted in-line with the fuel hose, located anywhere on a vehicle between the fuel tank and engine.

FUEL INJECTION:
A system replacing the carburetor that sprays fuel into the cylinder through nozzles. The amount of fuel can be more precisely controlled with fuel injection.

FULL FLOATING AXLE:
An axle in which the axle housing extends through the wheel giving bearing support on the outside of the housing.
The front axle of a four-wheel drive vehicle is usually a full floating axle, as are the rear axles of many larger (1 ton and over) pick-ups and vans.

FULL-TIME FOUR-WHEEL DRIVE:
A four-wheel drive system that continuously delivers power to all four wheels. A differential between the
front and rear driveshafts permits variations in axle speeds to control gear wind-up without damage.

FULL THROTTLE DETENT DOWNSHIFT:
A quick apply of accelerator pedal to its full travel, forcing a downshift.

FUSE:
A protective device in a circuit which prevents circuit overload by breaking the circuit when a specific amperage is present. The device is constructed around a strip or wire of a lower amperage rating than the circuit it
is designed to protect. When an amperage higher than that stamped on the fuse is present in the circuit, the strip or wire melts, opening the circuit.

FUSIBLE LINK:
A piece of wire in a wiring harness that performs the same job as a fuse. If overloaded, the fusible link will melt and interrupt the circuit.

FWD:
Front wheel drive.

Details

Parent Category: Maintenance Guide

Category: Engine Guide

Automotive terms Modern (D)

Automotive Technical terms and abbreviations overview used in the industry, Guide and explanations.

The following are examples of Mid Modern technical terms recommended for general use worldwide. For in-depth specific terms also see terms for historic vintage and specific areas such as Paint.

DATA LINK CONNECTOR (DLC):
Current acronym/term applied to the federally mandated, diagnostic junction connector that is used to monitor ECM/PC/TCM inputs, processing strategies, and outputs including diagnostic trouble codes (DTCs).

DEAD CENTER:
The extreme top or bottom of the piston stroke.

DECELERATION BUMP:
When referring to a torque converter clutch in the applied position, a sudden release of the accelerator pedal causes a forceful reversal of power through the drivetrain (engine braking), just prior to the apply plate actually being released.

DELAYED (LATE OR EXTENDED):
Condition where shift is expected but does not occur for a period of time, for example, where clutch or band engagement does not occur as quickly as expected during part throttle or wide open throttle apply of accelerator or when manually downshifting to a lower range.

DETENT:
A spring-loaded plunger, pin, ball, or pawl used as a holding device on a ratchet wheel or shaft. In automatic transmissions, a detent mechanism is used for locking the manual valve in place.

DETENT DOWNSHIFT:
(See kickdown.)

DETERGENT:
An additive in engine oil to improve its operating characteristics.

DETONATION:
An unwanted explosion of the air/fuel mixture in the combustion chamber caused by excess heat and compression, advanced timing, or an overly lean mixture, Also referred to as "ping".

DEXRON:
A brand of automatic transmission fluid.

DIAGNOSTIC TROUBLE CODES (OTCs):
A digital display from the control module memory that identifies the input, processor, or output device circuit that is related to the powertrain emission/driveability malfunction detected. Diagnostic trouble codes can be read by the MIL to flash any codes or by using a handheld scanner.

DIAPHRAGM:
A thin, flexible wall separating two cavities, such as in a vacuum advance unit.

DIESELING:
The engine continues to run after the car is shut off caused by fuel continuing to be burned in the combustion chamber.

DIFFERENTIAL:
A geared assembly which allows the transmission of motion between drive axles, giving one axle the ability to rotate faster than
the other, as in cornering.

DIFFERENTIAL AREAS:
When opposing faces of a spool valve are acted upon by the same pressure but their areas differ in size, the face with the larger area produces the differential force and valve movement. (See spool valve.)

DIFFERENTIAL FORCE:
(See differential areas)

DIGITAL READOUT:
A display of numbers or a combination of numbers and letters.

DIGITAL VOLT OHMMETER:
An electronic diagnostic tool used to measure voltage, ohms and amps as well as several other functions, with the readings displayed on a digital screen in tenths, hundredths and thousandths.

DIODE:
An electrical device that will allow current to flow in one direction only.

DIRECT CURRENT (DC):
Electrical current that flows in one direction only.

DIRECT DRIVE:
The gear ratio is 1:1, with no change occurring in the torque and speed input/output relationship.

DISC BRAKE:
A hydraulic braking assembly consisting of a brake disc, or rotor, mounted on an axle shaft, and a caliper assembly containing, usually two brake pads which are activated by hydraulic pressure. The pads are forced against the sides of the disc, creating friction which slows the vehicle.

DISPERSANTS:
Suspend dirt and prevent sludge buildup in a liquid, such as engine oil.

DOUBLE BUMP (DOUBLE FEEL):
Two sudden and forceful applies of a clutch or band.

DISPLACEMENT:
The total volume of air that is displaced by all pistons as the engine turns through one complete revolution.

DISTRIBUTOR:
A mechanically driven device on an engine which is responsible for electrically firing the spark plug at a pre-determined point of the piston stroke.

DOHC:
Double overhead camshaft.

DOUBLE OVERHEAD CAMSHAFT:
The engine utilizes two camshafts mounted in one cylinder head. One camshaft operates the exhaust valves, while the other operates the intake valves.

DOWEL PIN:
A pin, inserted in mating holes in two different parts allowing those parts to maintain a fixed relationship.

DRIVELINE:
The drive connection between the transmission and the drive wheels.

DRIVE TRAIN:
The components that transmit the flow of power from the engine to the wheels. The components include the clutch, transmission, driveshafts (or axle shafts in front wheel drive), U-joints and differential.

DRUM BRAKE:
A braking system which consists of two brake shoes and one or two wheel cylinders, mounted on a fixed backing plate, and a brake drum, mounted on an axle, which revolves around the assembly.

DRY CHARGED BATTERY:
Battery to which electrolyte is added when the battery is placed in service.

DVOM:
Digital volt ohmmeter

DWELL:
The rate, measured in degrees of shaft rotation, at which an electrical circuit cycles on and off.

DYNAMIC:
An application in which there is rotating or reciprocating motion between the parts.

Details

Parent Category: Maintenance Guide

Category: Engine Guide

Automotive terms Modern (E)

Automotive Technical terms and abbreviations overview used in the industry, Guide and explanations.

The following are examples of Mid Modern technical terms recommended for general use worldwide.For in-depth specific terms also see terms for historic vintage and specific areas such as Paint.

EARLY:
Condition where shift occurs before vehicle has reached proper speed, which tends to labor engine after upshift.

EBCM:
See Electronic Control Unit (ECU).

ECM:
See Electronic Control Unit (ECU)

ECU:
Electronic control unit.

ELECTRODE:
Conductor (positive or negative) of electric current.

ELECTROLYSIS:
A surface etching or bonding of current conducting transmission/transaxle components that may occur when grounding straps are missing or in poor condition.

ELECTROLYTE:
A solution of water and sulfuric acid used to activate the battery. Electrolyte is extremely corrosive.

ELECTROMAGNET:
A coil that produces a magnetic field when current flows through its windings.

ELECTROMAGNETIC INDUCTION:
A method to create (generate) current flow through the use of magnetism.

ELECTROMAGNETISM:
The effects surrounding the relationship between electricity and magnetism.

ELECTROMOTIVE FORCE (EMF)
The force or pressure (voltage) that causes current movement in an electrical circuit.

ELECTRONIC CONTROL UNIT:
A digital computer that controls engine (and sometimes transmission, brake or other vehicle system) functions based on data received from various sensors.
Examples used by some manufacturers include Electronic Brake Control Module (EBCM), Engine Control Module (ECM), Powertrain Control Module (PCM) or Vehicle Control Module (VCM).

ELECTRONIC IGNITION:
A system in which the timing and firing of the spark plugs is controlled by an electronic control unit, usually called a module. These systems have no points or condenser.

ELECTRONIC PRESSURE CONTROL (EPC) SOLENOID:
A specially designed solenoid containing a spool valve and spring assembly to control fluid mainline pressure. A variable current flow, controlled by the
ECM/PCM, varies the internal force of the solenoid on the spool valve and resulting mainline pressure. (See variable force solenoid.)

ELECTRONICS:
Miniaturized electrical circuits utilizing semiconductors, solid-state devices, and printed circuits. Electronic circuits utilize small amounts of power.

ELECTRONIFICATION:
The application of electronic circuitry to a mechanical device. Regarding automatic transmissions, electrification is incorporated into converter clutch lockup, shift scheduling, and line pressure control systems.

ELECTROSTATIC DISCHARGE (SD):
An unwanted, high-voltage electrical current released by an individual who has taken on a static charge of electricity. Electronic components can be easily damaged by ESD.

ELEMENT:
A device within a hydrodynamic drive unit designed with a set of blades to direct fluid flow.

ENAMEL:
Type of paint that dries to a smooth, glossy finish.

END BUMP (END FEEL OR SLIP BUMP):
Firmer feel at end of shift when compared with feel at start of shift.

END-PLAY:
The clearance/gap between two components that allows for expansion of the parts as they warm up, to prevent binding and to allow
space for lubrication.

ENERGY:
The ability or capacity to do work.

ENGINE:
The primary motor or power apparatus of a vehicle, which converts liquid or gas fuel into mechanical energy.

ENGINE BLOCK:
The basic engine casting containing the cylinders, the crankshaft main bearings, as well as machined surfaces for the mounting of other components such as the cylinder head, oil pan, transmission, etc.

ENGINE BRAKING:
Use of engine to slow vehicle by manually down-shifting during zero-throttle coast down.

ENGINE CONTROL MODULE (ECM):
Manages the engine and incorporates output control over the torque converter clutch solenoid. (Note: Current designation for the ECM in late model vehicles is PCM.)

ENGINE COOLANT TEMPERATURE (ECT) SENSOR:
Prevents converter clutch engagement with a cold engine; also used for shift timing and shift quality.

EP LUBRICANT:
EP (extreme pressure) lubricants are specially formulated for use with gears involving heavy loads (transmissions, differentials,etc.).

ETHYL:
A substance added to gasoline to improve its resistance to knock, by slowing down the rate of combustion.

ETHYLENE GLYCOL:
The base substance of antifreeze.

EXHAUST MANIFOLD:
A set of cast passages or pipes which conduct exhaust gases from the engine.

Details

Parent Category: Maintenance Guide

Category: Engine Guide

Automotive terms Modern (C)

Automotive Technical terms and abbreviations overview used in the industry, Guide and explanations.

The following are examples of Mid Modern technical terms C recommended for general use worldwide. For in-depth specific terms also see terms for historic vintage and specific areas such as Paint.

CALIPER:
A hydraulically activated device in a disc brake system, which is mounted straddling the brake rotor (disc). The caliper contains at
least one piston and two brake pads. Hydraulic pressure on the piston(s) forces the pads against the rotor

CAPACITY:
The quantity of electricity that can be delivered from a unit, as from a battery in ampere-hours, or output, as from a generator.

CAMBER:
One of the factors of wheel alignment. Viewed from the front of the car, it is the inward or outward tilt of the wheel. The top of the tire will
lean outward (positive camber) or inward (negative camber).

CAMSHAFT:
A shaft in the engine on which are the lobes (cams) which operate the valves. The camshaft is driven by the crankshaft, via a belt,
chain or gears, at one half the crankshaft speed.

CAPACITOR:
A device which stores an electrical charge.

CARBON MONOXIDE (CO):
A colorless, odorless gas given off as a normal byproduct of combustion. It is poisonous and extremely dangerous in confined areas, building up slowly to toxic levels without warning if adequate ventilation is not available.

CARBURETOR:
A device, usually mounted on the intake manifold of an engine, which mixes the air and fuel in the proper proportion to allow even
combustion.

CASTER:
The forward or rearward tilt of an imaginary line drawn through the upper ball joint and the center of the wheel. Viewed from the sides, positive caster (forward tilt) lends directional stability, while negative caster (rearward tilt) produces instability.

CATALYTIC CONVERTER:
A device installed in the exhaust system, like a muffler, that converts harmful byproducts of combustion into carbon dioxide and water vapor by means of a heat-producing chemical reaction.

CENTER CAP
Early center caps for automobiles were used to keeping dirt away from wheel bearings and spindle nut later just decorative.

CENTRIFUGAL ADVANCE:
A mechanical method of advancing the spark timing by using flyweights in the distributor that react to centrifugal force generated by the distributor shaft rotation.

CENTRIFUGAL FORCE:
The outward pull of a revolving object, away from the center of revolution. Centrifugal force increases with the speed of rotation.

CETANE RATING:
A measure of the ignition value of diesel fuel. The higher the cetane rating, the better the fuel. Diesel fuel cetane rating is roughly comparable to gasoline octane rating.

CHASSIS
The load-bearing underpart of a motor vehicle.

CHECK VALVE:
Any one-way valve installed to permit the flow of air, fuel or vacuum in one direction only.

CHOKE:
The valve/plate that restricts the amount of air entering an engine on the induction stroke, thereby enriching the air/fuel ratio.

CHUGGLE:
Bucking or jerking condition that may be engine related and may be most noticeable when converter clutch is engaged; similar to the
feel of towing a trailer.

CIRCLIP:
A split steel snapring that fits into a groove to hold various parts in place.

CIRCUIT BREAKER:
A switch which protects an electrical circuit from overload by opening the circuit when the current flow exceeds a pre-deter- mined level. Some circuit breakers must be reset manually, while most reset automatically.

CIRCUIT:
Any unbroken path through which an electrical current can flow. Also used to describe fuel flow in some instances.

CIRCUIT, BYPASS:
Another circuit in parallel with the major circuit through which power is diverted.

CIRCUIT, CLOSED:
An electrical circuit in which there is no interruption of current flow.

CIRCUIT, GROUND:
The non-insulated portion of a complete circuit used as a common potential point. In automotive circuits, the ground is composed of metal parts, such as the engine, body sheet metal, and frame and is usually a negative potential.

CIRCUIT, HOT:
That portion of a circuit not at ground potential. The hot circuit is usually insulated and is connected to the positive side of the battery.

CIRCUIT, OPEN:
A break or lack of contact in an electrical circuit, either intentional (switch) or unintentional (bad connection or broken wire).

CIRCUIT, PARALLEL:
A circuit having two or more paths for current flow with common positive and negative tie points. The same voltage is applied to each load device or parallel branch.

CIRCUIT, SERIES:
An electrical system in which separate parts are connected end to end, using one wire, to form a single path for current to flow.

CIRCUIT, SHORT:
A circuit that is accidentally completed in an electricty

CLAMPING (ISOLATION) DIODES:
Diodes positioned in a circuit to prevent self-induction from damaging electronic components.

CLEARANCE VOLUME:
The swept volume in a cylinder above the piston remaining when it reaches TDC (top dead center).

CLEARCOAT:
A transparent layer which, when sprayed over a vehicle's paint job, adds gloss and depth as well as an additional protective coating

CLOCKING:
Mainly a pre digital Illegal operation by tampering with a vehicle's odometer reading to show less miles.

CLOCKSPRING:
A spiral spring similar to a clock spring located between the steering wheel and column.

CLUTCH:
Part of the power train used to connect/disconnect power to the rear wheels.

CLUTCH, FLUID:
The same as a fluid coupling. A fluid clutch or coupling performs the same function as a friction clutch by utilizing fluid friction and inertia as opposed to solid friction used by a friction clutch.

CLUTCH, FRICTION:
A coupling device that provides a means of smooth and positive engagement and disengagement of engine torque to the vehicle powertrain. Transmission of power through the clutch is accomplished by bringing one or more rotating drive members into contact with complementing driven members.

COAST:
Vehicle deceleration caused by engine braking conditions.

COEFFICIENT OF FRICTION:
The amount of surface tension between two contacting surfaces; identified by a scientifically calculated number.

COIL:
Part of the ignition system that boosts the relatively low voltage supplied by the car's electrical system to the high voltage required to fire the spark plugs.

COLD CRANKING AMPS (CCA)
The amount of current a battery can provide to start for around 30 seconds .

COMBINATION MANIFOLD:
An assembly which includes both the intake and exhaust manifolds in one casting.

COMBINATION VALVE:
A device used in some fuel systems that routes fuel vapors to a charcoal storage canister instead of venting them into the atmosphere. The valve relieves fuel tank pressure and allows fresh air into the tank as the fuel level drops to prevent a vapor lock situation.

COMBUSTION CHAMBER:
The part of the engine in the cylinder head where combustion takes place of the fuel/air mixture.

COMPOUND GEAR:
A gear consisting of two or more simple gears with a common shaft.

COMPOUND PLANETARY:
A gearset that has more than the three elements found in a simple gearset and is constructed by combining members of two planetary gearsets to create additional gear ratio possibilities.

COMPRESSION CHECK:
A test involving removing each spark plug and inserting a gauge. When the engine is cranked, the gauge will record a pressure reading in the individual cylinder. General operating condition can be determined from a compression check.

COMPRESSION RATIO:
The ratio of the volume between the piston and cylinder head when the piston is at the bottom of its stroke (bottom dead center) and when the piston is at the top of its stroke (top dead center).

COMPUTER:
An electronic control module that correlates input data according to prearranged engineered instructions; used for the management of an actuator system or systems.

CONDENSER (1):
An electrical device which acts to store an electrical charge, preventing voltage surges.

CONDENSER (2):
A radiator-like device in the air conditioning system in which refrigerant gas condenses into a liquid, giving off heat.

CONDUCTOR:
Any material through which an electrical current can be transmitted easily.

CONNECTING ROD:
The connecting link between the crankshaft and piston.

CONSTANT VELOCITY JOINT:
Type of universal joint in a halfshaft assembly in which the output shaft turns at a constant angular velocity without variation, provided that the speed of the input shaft is constant.

CONSTINUOSLY VARIABLE TRANSMISSION (CVT)
Automatic type variable transmission that can change through a continuous range of gear ratios.

CONTINUITY:
Continuous or complete circuit. Can be checked with an ohmmetec

CONTROL ARM:
The upper or lower suspension components which are mounted on the frame and support the ball joints and steering knuckles.

CONVENTIONAL IGNITION:
Ignition system which uses breaker points.

CONVERTER:
or as torque converter

CONVERTER LOCKUP:
The switching from hydrodynamic to direct mechanical drive, usually through the application of a friction element called the converter clutch.

COOLANT:
Mixture of water and anti-freeze circulated through the engine to carry off heat produced by the engine.

CORROSION INHIBITOR:
An inhibitor in ATF that prevents corrosion of bushings, thrust washers, and oil cooler brazed joints.

COUNTERSHAFT:
An intermediate shaft which is rotated by a main-shaft and transmits, in turn, that rotation to a working part.

COUPLING PHASE:
Occurs when the torque converter is operating at its greatest hydraulic efficiency. The speed differential between the impeller and the turbine is at its minimum. At this point, the stator freewheels, and there is no torque multiplication.

CRANKCASE:
The lower part of an engine in which the crankshaft and related parts operate.

CRANKSHAFT:
Engine component (connected to pistons by connecting rods) which converts the reciprocating (up and down) motion of pistons to rotary motion used to turn the driveshaft.

CRANKSHAFT JOURNAL:
Part of the crankshaft attached to the engine's connecting rods and pistons that rotates in a main bearing.

CRANKSHAFT THROW:
The distance between the centerline of the crankshaft and the furthest offset of a big end journal.

CROSSMEMBER
bolted across the underside of a monocoque/unibody type motor vehicle,transverse to the main structure.

CURB WEIGHT:
The weight of a vehicle without passengers or payload, but including all fluids (oil, gas, coolant, etc.) and other equipment speci-
fied as standard.

CURRENT:
The flow (or rate) of electrons moving through a circuit. Current is measured in amperes (amp).

CURRENT FLOW CONVENTIONAL:
Current flows through a circuit from the positive terminal of the source to the negative terminal (plus to minus).

CURRENT FLOW, ELECTRON:
Current or electrons flow from the negative terminal of the source, through the circuit, to the positive terminal (minus to plus). CV-JOINT: Constant velocity joint.

CYCLIC VIBRATIONS:
The off-center movement of a rotating object that is affected by its initial balance, speed of rotation, and working angles.

CYLINDER BLOCK:
see engine block.

CYLINDER HEAD:
The detachable portion of the engine, usually fastened to the top of the cylinder block and containing all or most of the combustion chambers. On overhead valve engines, it contains the valves and their operating parts. On overhead cam engines, it contains the camshaft as well.

CYLINDER:
In an engine, the round hole in the engine block in which the piston(s) ride up and down.