Air Filter
Description: The typical air filter is a disposable,
pleated-paper element with a sealing gasket made of synthetic material. Filters
come in two main types: the panel style as used on most fuel-injected cars and
the radial style, which is usually used on carbureted vehicles.
Purpose: The air filter traps dirt particles, which can
cause damage to engine cylinders, walls, pistons and piston rings. The air
filter also plays a role in keeping contaminants off the airflow sensor (some
fuel-injected cars) and sometimes in cleaning the air that enters the crankcase
for crankcase ventilation. The air filter also serves as a silencer for your
car’s intake system. Your car’s engine can use close to 40,000 litres of air for
every 3.5 litres of fuel burned, so it’s easy to see how big a job the air
filter has.
Maintenance Tips/Suggestions: Although your car’s owner’s
manual may specify an inspection interval for the air filter, it’s really best
that it be checked at every oil change. Dirty and dusty driving conditions will
require more frequent filter replacements, so keep this in mind. Driving with a
dirty filter restricts the air entering the engine, and if severe, can impact
fuel economy and performance. If you decide to change the filter yourself,
always do so with the engine off. Never start or run the engine with the air
filter out of place. Most filters can be easily replaced by removing snap clips,
a clamp or several screws. Make sure you use the filter specified for your car’s
engine; do not try to make a filter fit. An improperly fitting filter can allow
unfiltered air into the engine, causing engine damage.
Carburetion
Description: Carburetion refers to the use of a carburetor
as a means of controlling an engine’s air/fuel ratio. Carburetors were used on
most cars through the mid-1980s, when carmakers began a large-scale changeover
to fuel injection. A carburetor holds fuel in a small reservoir called a float
bowl. This reservoir is connected to a passageway leading to a venturi, a device
that uses pressure differential to help meter fuel into the engine.
Conventionally referred to as "barrels", it refers to the number of venturis in
the carburetor. A one-barrel carburetor has one venturi; a two-barrel carburetor
has two venturis, and so on, up to four venturis. Around 1980, carmakers began
to add mixture control solenoids and other electronic devices to carburetors, to
make them more effective by allowing additional control through an electronic
engine control system.
Purpose: The carburetor mixes fuel with air in the right
ratios for all engine-operating conditions.
Maintenance Tips/Suggestions: Replace the fuel filter once
a year. If your car demonstrates a loss of performance or fuel economy, have the
engine performance evaluated by a good shop with qualified technicians. The
carburetor’s health will also be checked out at this time. Other symptoms of
carburetor problems include hard starting, stalling, hesitation, rough idle,
black smoke from the tailpipe, or failing an emissions test. If you experience
any of these problems, have them checked out at once to avoid more costly
repairs.
Fuel Filter
Description: The typical fuel filter for most
fuel-injected cars consists of a high-pressure canister filled with filtering
media. Filters may have clamped, threaded or special fittings to ensure reliable
connection to the fuel system. Filters for carbureted engines may be located at
the inlet of the carburetor or inline. Filters for carbureted engines do not
need to withstand the same pressures as those for fuel-injected engines.
Purpose: Fuel filters trap harmful contaminants that may
cause problems with carburetors and intricate fuel injectors. Fuel filters for
carbureted engines only clean the fuel before it enters the float bowl.
Injection filters, on the other hand, clean the fuel whenever the fuel pump runs
(unless the fuel injection system is a "returnless" design). Fuel moves
continuously up the supply side, through the filter to the fuel rail or throttle
body. The fuel that doesn't make it into the engine returns to the tank and the
whole process starts over again. With a full tank of gas, the filter may clean
the volume of fuel in the tank many times before it's all used.
Maintenance Tips/Suggestions: On carbureted cars, replace
the filter once a year. On cars with fuel injection, some carmakers don't
recommend replacing the filter at all during the first 170,000 kilometres of
"normal" driving. Since "normal" usually constitutes severe driving because of
less than normal conditions, it's best to replace the filter every two years or
40,000 kilometres. A contaminated filter can restrict fuel flow from your car’s
electric fuel pump, eventually taking a toll on its life. Frequent filter
replacements remove all doubt about whether the filter may cause other problems
down the road.
Most filters on domestic cars and trucks hide underneath on the frame or
body. Just the opposite is true on the imports. They usually put their filters
somewhere in the engine compartment. If you decide to change the filter
yourself, be careful. Fuel injection systems maintain pressure in the lines that
must be relieved prior to filter replacement. Don’t forget that gasoline is
extremely flammable. Procedures vary for relieving pressure. Also, some filters
require special tools to replace the fuel filter. Because of these
technicalities and because of most filter locations, it’s best to have your
car’s fuel filter replaced by a qualified service professional.
Fuel Injection
Description: Fuel injection consists of a throttle body to
control airflow, the fuel injectors, various engine sensors, an electric fuel
pump and a fuel filter. The system is controlled by the car’s powertrain control
module (PCM), which makes all decisions for controlling the injection system.
Most early fuel injection systems used a throttle-body design, where one or more
injectors were mounted on a throttle body, resembling a carburetor. Use of the
throttle body system faded away gradually as multi-port fuel injection became
more prevalent. Multi-port uses a separate fuel injector for each cylinder,
located near each cylinder’s intake valve port. Virtually all engines now use
multi-port injection.
Purpose: Fuel injection delivers fuel to the engine in
exactly the right amount for all engine-operating conditions. Not only does the
system provide better control for fuel economy, performance and emissions, it
also does away with many of the maintenance requirements of a carburetor.
Maintenance Tips/Suggestions: On cars with fuel injection,
some carmakers don't recommend replacing the filter at all during the first
170,000 kilometres of "normal" driving. Since "normal" usually constitutes
severe driving because of less than normal conditions, it's best to replace the
filter every two years or 40,000 kilometres. A contaminated filter can restrict
fuel flow from your car’s electric fuel pump, eventually taking a toll on its
life. Frequent filter replacements remove all doubt about whether the filter may
cause other problems down the road.
On 1996 and newer vehicles, your car’s fuel injection system is integrated
with a second-generation onboard diagnostic system, known as OBDII. The PCM
stores a Diagnostic Trouble Code (DTC) when it detects a problem in one of the
monitored circuits. A professional technician can access this information using
a scan tool connected to the vehicle’s Data Link Connector (DLC). Although many
DTCs are sensor-related, it does not necessarily indicate a faulty sensor. There
may be problems in that sensor’s circuit, or there may be several interrelated
problems.
Areas of the country with an emissions testing program are placing added
value on OBDII checks, where this technology may be used in place of tailpipe
testing. The system also alerts you with a Malfunction Indicator Lamp (MIL),
indicating that the system has detected a problem, which could cause excessive
emissions. This light is usually labelled SERVICE ENGINE SOON or CHECK ENGINE.
If the light appears, you should have its cause investigated by a professional
technician at your earliest opportunity. If the light flashes, the condition is
more severe and must be checked out immediately to prevent damage to the
catalytic converter.
Fuel Pump
Description: A mechanical fuel pump is most often used on
cars with carburetors. This type of pump produces low pressure and is usually
driven by the engine. Cars all use electric fuel pumps nowadays because of the
universal application of fuel injection and its need for higher pressures.
Electric fuel pumps are almost always located inside the gas tank, but there are
some applications where the pump may be located along the frame or uni-body
channel. The pump has a strainer at its pickup to filter out contaminants and
uses an electric motor for power. Fuel is used as a lubricant and coolant for
the motor. The electric fuel pump has its own electrical control circuit,
typically consisting of wiring, a fuse and a relay. This circuit interacts with
the car’s powertrain control module (PCM), which governs and monitors fuel pump
operation.
Purpose: The fuel pump provides fuel with the proper
pressure and volume for delivery by the carburetor or fuel injection system. The
electric fuel pump circuit also employs various safeties that stop the pump from
running in the event of an accident.
Maintenance Tips/Suggestions: Mechanical fuel pumps
require no maintenance, but should be replaced at the first sign of a problem.
Pressure or volume may drop off, giving an early warning sign of impending pump
failure. A professional service technician can usually identify a pump problem
quickly. With fuel-injected vehicles, regular fuel filter changes can help
extend the life of the electric fuel pump. It's best to replace the filter every
two years or 40,000 kilometres. A contaminated filter can restrict fuel flow
from the electric fuel pump, eventually taking a toll on its life.
You can also help protect the pump by keeping the tank at least half-full
at all times. Since fuel cools the pump, having plenty of fuel in the tank helps
keep the pump from getting too warm, which could damage it.
Another good reason to keep the gas tank at least half-full is to reduce
the chances of sediment pick-up at the fuel pump inlet strainer. A restricted
strainer can starve the pump, causing it to overheat and fail. If you own a Ford
or Lincoln-Mercury vehicle, check your owner’s manual for the location of the
fuel pump shut-off switch. This switch is designed to electrically disconnect
the fuel pump in the event of an accident. Sometimes, an abrupt jarring of your
car may be enough to cause this switch to open. It’s good to know where the
switch is so you can try resetting it if your car does not start.
A faulty electric fuel pump can cause various symptoms including a loud
pump whine, engine no-start, hesitation, poor performance and stalling. If your
car demonstrates any of these performance problems, have it checked out by a
qualified service technician. Replacing the fuel pump generally involves removal
of the fuel tank.
Fuel Storage
Description: The fuel tank is usually made of stamped
steel or plastic. The tank is held in place with steel straps. In some cases, a
bracket-and-strap arrangement is used.
Purpose: The fuel tank stores gasoline for the engine,
holds the electric fuel pump and sending unit, and provides a connection to the
vapour collection/recovery components of the emissions system. The tank also has
a filler neck, which restricts fuelling to unleaded fuel nozzles. On 1996 and
newer cars, the mouth of the filler neck is designed specially for
OBDII-compatible gas caps.
Maintenance Tips/Suggestions: Unless damaged, fuel tanks
last for the life of the vehicle. On many cars, the fuel tank needs to be
removed in order to replace the fuel pump. On 1996 and newer cars, a light on
the dash, labelled SERVICE ENGINE SOON or CHECK ENGINE may turn on if the gas
cap is left loose after refuelling. Make sure the gas cap is always installed
properly after you refuel. Turn the cap to the right until it clicks in place.
Turbo & Supercharger
Description: A turbocharger uses an exhaust-gas driven
turbine wheel, which drives a compressor wheel to boost air delivery to the
engine. A supercharger uses mechanically driven rotors, usually from a belt, to
boost air delivery to the engine.
Purpose: Turbochargers and superchargers enable increased
burning of air and fuel by forcing more of it into the engine’s cylinders,
thereby improving an engine’s breathing characteristics.
Maintenance Tips/Suggestions: Check your car’s owner’s
manual for maintenance requirements of the turbocharger or supercharger. The
turbocharger or supercharger on your car’s engine will last for many thousands
of kilometres if cared for properly through a regular engine maintenance
regimen. This includes regular oil and filter changes, engine performance
check-ups, and cooling system maintenance. If you notice that engine performance
drops off, that the engine is using oil, or notice other problems with coolant
temperature or oil pressure, it’s wise to have these looked into as soon as
possible by a qualified professional.
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