Glossary “percentage reduction” Definition:
Additional materials must be added in certain proportions or parts.
p
percolation
Glossary “percolation” Definition:
Condition in which the fuel bowl vent fails to open when the engine is turned off and internal pressure forces raw fuel through the main jets into the manifold.
performance test
Glossary “performance test” Definition:
1). Readings of the temperature and pressure, under controlled conditions, to determine if an air-conditioning system is operating at full efficiency. 2). A test to determine if a system or sub-system is performing at maximum efficiency.
perimeter frame
Glossary “perimeter frame” Definition:
Conventional chassis frame design that is similar in construction to a ladder frame, having full-length side rails that support the body at its greatest width, providing optimum protection to passengers in the event of a side impact.
pending DTC
Glossary “pending DTC” Definition:
DTC stored on first occurrence of a fault. May be retrieved as a continuous code DTC. Fault must occur again as required by the monitor to light the MIL.
penetrating oil
Glossary “penetrating oil” Definition:
Special, thin oil that penetrates rust and/or tight threads and helps in the removal of stubborn nuts and bolts.
pentroof combustion chamber
Glossary “pentroof combustion chamber” Definition:
A flat or pancake shaped combustion chamber that has the overhead valve heads that are almost parallel to the top of the pistion and the spark plug at or near the center of the chamber. This design provides a very short distance for the flame front to travel, excellent air flow characteristics and efficient combustion.
PERA
Glossary “PERA” Definition:
Production Engine Remanufactures Association.
PEL
Glossary “PEL” Definition:
Permissible Exposure Limit.
pellet thermostat
Glossary “pellet thermostat” Definition:
Engine coolant thermostat having a wax pellet as a power element, which extands when heated and shrinks when cooled, connected through a piston to a valve, controlling the coolant flow from the engine to the radiator.
pellet bed catalytic converter
Glossary “pellet bed catalytic converter” Definition:
Catalytic converter design having a stainless steel shell and a bed of catalyst-coated ceramic pellets that can be replaced using special vibrator/aspirator equipment.
pearlescent paint
Glossary “pearlescent paint” Definition:
Paint with fine mica particles blended into the pigment.
pedal clearance
Glossary “pedal clearance” Definition:
Amount of downward brake pedal movement, 1/4 inch (6.35 mm) or so, before the pushrod contacts the piston of the master cylinder.
pedal play
Glossary “pedal play” Definition:
The distance the clutch pedal and release bearing assembly move from fully engaged position to the point at which the release bearing contacts the pressure plate lelease levers.
peel test
Glossary “peel test” Definition:
A destructive method of testing that mechanically separates a lap joint by peeling it.
peen
Glossary “peen” Definition:
1). To shape metal by pounding it. 2). Ball shaped end of a hammer head.
peak and hold injector
Glossary “peak and hold injector” Definition:
A peak and hold injector is typically used for TBI and some port low-resistance injector systems.
pearl paint
Glossary “pearl paint” Definition:
Paint with medium size reflective pigment particles, such as mica, that gives it luster or shine that tends to change color with the viewing angle.
peak inverse voltage (PIV)
Glossary “peak inverse voltage (PIV)” Definition:
The maximum reverse voltage which a semiconductor junction can withstand without permanently damaging the junction
peak out
Glossary “peak out” Definition:
Engine speed at which maximum horsepower is developed.