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 100,000 miles 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 24,000 miles. 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 labeled 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.
