MTTC Automotive Trade Test key terms

The relationship between the total cylinder volume with the piston at bottom dead center and the volume remaining above the piston at top dead center, usually written as a figure like 10:1.

A diagnostic procedure that introduces regulated compressed air into a sealed cylinder and measures the percentage escaping, while listening at the intake, exhaust, and crankcase to locate the leak.

The precise crankshaft positions at which the intake and exhaust valves open and close, determined by camshaft lobe shape and the alignment of timing marks.

An engine performance check that reads intake manifold vacuum at idle and during snap throttle, revealing restrictions, vacuum leaks, and poor ring or valve sealing.

The percentage of fuel delivery the powertrain control module adds or subtracts from its base calculation to reach the target air-fuel ratio, reported as short-term and long-term values.

A device in the intake tract that measures the mass of air entering the engine, usually by heated wire or film, so the control module can calculate the correct fuel quantity.

A fluid coupling between engine and transmission that multiplies torque at low speed through a stator and allows the vehicle to idle in gear without a mechanical clutch.

A gear arrangement of a sun gear, planet carrier, and ring gear that produces different ratios depending on which member is held, driven, or allowed to rotate freely.

Friction elements inside an automatic transmission that hold or drive planetary members to select each gear ratio; bands wrap a drum while clutches stack alternating plates.

The main hydraulic pressure the transmission pump supplies to the control valve body, used to apply clutches and bands and typically raised under heavy load.

A check performed with the brakes held and throttle opened fully in gear, comparing maximum engine speed against specification to evaluate the torque converter and apply components.

The small gap between the clutch release bearing and the pressure plate fingers, or the pedal travel before resistance, that ensures the clutch fully engages when released.

A brass or composite blocking ring in a manual gearbox that friction-matches the speed of a gear to the output shaft so the shift collar can engage without grinding.

The bearing that transfers motion from the clutch linkage to the rotating pressure plate fingers, allowing the clutch to disengage when the pedal is pressed.

The forward or rearward tilt of the steering axis viewed from the side, which affects straight-line stability and steering return; too little causes wander and too much raises effort.

The inward or outward tilt of the top of a wheel viewed from the front, which influences tire wear and cornering grip; excessive negative or positive values scrub the tire edge.

The amount the front edges of the tires point toward or away from each other, adjusted to counteract rolling forces; incorrect toe rapidly wears tires and affects steering feel.

The average direction the rear wheels point relative to the vehicle centerline, which must be corrected before front alignment or the steering wheel will sit off center.

A change in toe that occurs as the suspension moves through its travel, caused by incorrect tie rod or control arm geometry, producing unpredictable steering on rough roads.

A flexible socket-and-stud pivot connecting the control arm to the steering knuckle, allowing suspension movement and steering rotation while carrying vertical loads.

A closed circuit in which brake fluid transmits pedal force through a master cylinder and lines to calipers or wheel cylinders, using incompressible fluid to create clamping force.

The loss of braking effectiveness caused by heat, either from fluid boiling and forming compressible vapor or from friction material losing its coefficient of friction.

The process of removing trapped air from a hydraulic brake circuit by opening a bleeder screw while pressure is applied, then closing it before the pedal is released.

A system that monitors wheel speed sensors and rapidly modulates hydraulic pressure to prevent wheel lockup during hard braking, preserving steering control on low-friction surfaces.

A magnetic or inductive device mounted near a tone ring that reports each wheel's rotational speed to the anti-lock and stability control modules.

A meter function that measures electrical resistance in ohms, used to check continuity, coil windings, and sensor resistance while the circuit is unpowered.

A measurement of the difference in potential across a conductor or connection while current flows, revealing resistance that a resistance reading alone might miss.

Current that continues to flow from the battery after all accessories are switched off, often from a stuck relay or module that fails to sleep, draining the battery overnight.

The fluid that circulates in an air conditioning system, absorbing heat as it evaporates at low pressure and releasing it as it condenses at high pressure.

The number of degrees a refrigerant vapor is above its saturation temperature at a given pressure, used to verify the expansion device is feeding the evaporator correctly.

Pulling a deep vacuum on a sealed air conditioning system with a pump to remove air and moisture before charging, verified with a vacuum gauge and hold test.

A calibrated hand tool that signals or limits applied twisting force so fasteners reach a specified value, essential for cylinder heads, suspension, and wheel hardware.

A fastener tightened past its elastic limit into the plastic range, then often turned a specified additional angle; it must be replaced rather than reused.

A precision measuring instrument with a calibrated screw and thimble used to read outside or inside dimensions to thousandths of an inch or hundredths of a millimeter.

Ongoing, low-stakes checks of student understanding during instruction, such as questioning or quick demonstrations, used to adjust teaching before a graded evaluation.

An evaluation given at the end of a unit or course to measure achievement against objectives, such as a written test or a scored hands-on task.

Planning lessons with varied content, process, or product so students with different readiness levels and learning needs can all meet the same learning objective.

Breaking a job into its ordered steps and required knowledge so instruction and assessment can target each part of the performance in sequence.

A procedure that isolates hazardous energy, applies a personal lock and tag, and verifies zero energy before service, preventing unexpected startup or release.

Wearable gear such as safety glasses, gloves, and hearing protection selected for the task to shield the worker from specific hazards.

A standardized document supplied with a hazardous chemical that lists its hazards, handling precautions, first aid measures, and spill response steps.