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Passive Restraint Systems
Automatically actuated systems designed to protect the driver and passengers in a vehicle in case of an accident. Air bags and automatic seat belts are examples of passive restraint systems. |
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PDC
Park Distance Control - tells the driver the distance between the car's front or rear bumper and any other fairly large object. This makes it much easier to park the car even in very restricted spaces. |
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Pearl Paint
A type of paint system that is similar to metallic paint, but instead of minute metal particles it uses mica -- a kind of semi transparent, crystalline mineral. The mica absorbs and reflects light in prismatic fashion, giving dramatic, multi-dimensional effects to the paint. |
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PFI
Port Fuel Injection - An injection system that uses one injector at the intake port of each cylinder, it's role is to spray past the intake valves.
:: Click for detailed PFI information |
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Ping
A metallic rattling sound produced by the engine during acceleration. It is usually due to incorrect ignition timing or a poor grade of fuel. |
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Piston Ring
An open-ended ring which fits into a groove on the outer diameter of the piston. Its chief function is to form a seal between the piston and cylinder wall. Most automotive pistons have three rings: two for compression sealing; one for oil sealing.
:: Click for detailed Piston Ring information |
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Plenum Chamber
An enclosed area with a volume of gas in it that is under greater pressure than the surrounding container. Located between the throttle body and the runners of an intake manifold, used to distribute the intake charge evenly and to enhance engine breathing. |
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Porting and Polishing
One of the best ways to get extra 'power' out of your engine is to port and polish your cylinder heads. Anyone who's been in the engine business for any length of time will tell you that one of the best ways to increase horse power in just about any engine is to (among other things) port & polish (P&P) the cylinder heads. How far you go with porting really depends what you are trying to accomplish with your motor and how you plan to drive it.
:: Click for detailed Porting and Polishing information |
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Positraction Differential
A positraction differential (aka Limited Slip Differential (LSD)) is a special traction Differential. Its purpose is to improve the way your differential performs under adverse conditions. When one wheel starts to slip, these differentials transfer the torque to the wheel that is not slipping. The car can then continue to go forward. There are several different kinds of positraction differentials, but all of them are based on a friction device to provide resistance to normal differential operation.
:: Click for detailed Positraction Differential information |
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Power Steering
The power steering pump sends pressure to the racks spool valve, the valve is incorporated with the pinion gear or input shaft to the rack. When you turn your steering wheel a shaft connected to it applies torque to the input shaft. As the amount of torque increases the valve gradually opens and allows the pressurized fluid to travel and push against a fixed piston on the racks shaft.
:: Click for detailed Power Steering information |
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Power Steering - Troubleshooting
My power steering rack's boots are full of fluid. Can't I just replace the boot?
Sorry. No. It won't work. The fluid leaked into the boot because the shaft seal or lower pinion seal failed. The boot is only designed to keep dust, dirt and water out of the rack. The pressure in the steering system can reach up to 110 bar ( one bar equals about 14.5 psi) or 1595 psi. Since the atmosphere around you and the rack is only about 14.7 psi and the pressure coming out of the rack is so much greater, replacing the boot will not solve the problem. It's only a matter of time before the fluid fills up the boot all the way and leaks out of the boot. The solution is to replace the rack and you might as well put on a fresh set of boots while you are at it.
The power steering pump is making an awful groan or grinding noise. What's the problem?
This could be caused by two problems. First, the pump could be low on fluid so its "cavitating" - when bubbles form in the fluid low pressure area and collapse in a higher pressure area of the pump, causing noise, damage and a loss of capacity. Cavitating is not good. If you continue to run the pump with this problem if will wear out very very quickly. Second, your pump is already worn out. A worn pump will not fix itself. Time to place the pump and check for any leaks in the system (such as the rack).
:: Click for detailed Power Steering - Troubleshooting information |
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Power Stroke
One of the four 180-degree full "sweeps" of the piston moving in the cylinder of a four-stroke, internal-combustion engine (originally devised by Nikolaus Otto in 1876). During the power stroke, the piston moves from TDC to BDC as the burning air/fuel mixture forces the piston down the cylinder. Note: The 180-degree duration of the power stroke is commonly longer than the duration between top dead center and the exhaust-valve opening point, sometimes referred to as the true "Power Cycle." The power stroke is followed by the exhaust stroke. |
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PPE
Pedestrian Protection Efforts (Nissan Tech) - Vehicle components that may come in contact with a pedestrian in a collision are designed to deform or break away easily for better impact energy absorption. This is just one of many approaches Nissan is taking to help reduce pedestrian injuries.
:: Click for detailed PPE information |
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Pressure Plate
A spring-loaded plate (part of the clutch) that transmits power to the driven (friction) plate when the clutch is engaged. |
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Press Fit
The mating of two parts under pressure, due to the inner diameter of one being smaller than the outer diameter of the other, or vice versa; an interference fit. |
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PS
PferdeStärke:This unit is no longer a lawful unit, but is still commonly used in Europe, South America and Japan, especially by the automotive and motorcycle industry.
:: Click for detailed PS information |
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Pushrod
A steel rod between the hydraulic valve lifter and the valve rocker arm in overhead valve (OHV) engines. Pushrods are used to transfer reciprocating motion from the cam followers to the rocker arms.
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