Air flow meter

Measures the air flowing into the engine and
sends the information to the ECU - which helps
calculate the exact amount of fuel required.

Air Mass sensor

This measures the air mass flowing into the
engine and sends this to the ECU. The ECU
uses this information to help calculate the
required amount of injected fuel.

Auxiliary Air Valve

This air valve allows the engine to receive
additional air during warm up, for optimum
performance and economy.

Canister Purge Valve

Fuel vapours that form in the fuel tank are
collected in a charcoal filter. The canister
purge valve then passes these gasses into
the engine.

Cold Start Valve

Injects additional fuel into the intake manifold
during the start up and warm up phase.

Electric Fuel Pump

Ensures a constant supply of fuel to the engine
(It can be installed directly into the fuel tank or
in the fuel line).

Electric Secondary Air Pump

Complying with current emissions legislation,
the secondary air pump blows fresh air into
the exhaust system after the start up,
ensuring that the CAT reaches operating
temperature quickly and is not damaged
by excess fuel.

Electromagnetic Injector

This sprays fuel onto the inlet valve via the
inlet manifold, when electronically triggered
by the ECU.

Electronic Control Unit (ECU)

50 million pieces of information are handled
every second by the ECU, from all the engine
sensors. It determines the quantity of fuel to
suit every condition, controls the injectors, and
maintains other components. In modern systems,
it can also control ignition and diagnose faults.

Electronic Idle Speed ECU

Controls the idle actuator and maintains
a constant engine idle speed.

Engine Temperature Sensor

This measures the engine temperature in the
coolant system and sends this information
to the ECU.

Fuel Accumulator

Ensures the fuel supply system is kept under
pressure after the engine has been switched
off. This improves the start phase in specific
petrol injection systems.

Fuel Filter

Removes contamination from the fuel.

Fuel Line Pressure Dampener

Damps down oscillation wthin fuel system.

Fuel Rail

Feeds fuel at pressure to the injectors.

Fuel System Pressure Regulator

Maintains a constant fuel pressure for fue
l that is supplied to the fuel rail.

Idle Actuator

Maintains a constant idle speed.

Knock Sensor

Converts engine combustion vibrations
into electronic signals and sends this
information to the ECU. The ECU then
adjusts the ignition to prevent damage
to the engine.

Lambda Sensor

Once the engine has reached operating
temperature this sensor measures the
oxygen content of the exhaust gas and
sends this information to the ECU which
then controls the air/fuel mixture. Lambda
sensors should be replaced according to
manufacturers instructions. For some
systems there are sensors at either
side of the catalytic converter.

Mechanical Injector

Sprays fuel onto the valves when a
predetermined pressure is reached. One
injector is used for each engine cylinder.

Mixture Controller Unit

Combines the work of the Air Flow Meter
and the Fuel Distributor. It measures the
amount of air flowing into the engine and
determines the quantity of fuel needed
for injection.

Pedal Sensor

This records the position of the accelerator
and sends the information to the ECU as an
electronic signal (as opposed to conventional
cables). The ECU uses this information to
control the air/fuel mixture.

Pressure Sensor (Altitude)

Measures the atmospheric pressure and
sends this information to the ECU as an
electronic signal.

Pressure Sensor (MAP)

Measures the pressure in the intake manifold
and sends this information to the ECU. The
ECU uses this information to control the
ignition timing and the air/fuel mixture.

Single Point Injector

This single injector supplies fuel to all the
engine cylinders. It sprays fuel into the inlet
manifold when triggered by the ECU.

Speed and Reference Mark Sensor

A speed and reference mark sensor
measures the engine speed and piston
position. This information is sent to the
ECU which calculates the air/fuel mixture
and ignition timing.

Thermo-Time Switch

Limits the amount of additional fuel injected
by the cold start valve into the intake
manifold during the start up.

Throttle Control Device

Uses information from the ECU to
electronically open and close the
throttle valve.

Throttle-Valve Switch

This measures the position of the
throttle-valve. The information is sent
to the ECU which can alter
air/fuel mixture.

Throttle-Valve Sensor

Measures the position of the throttle valve.
It sends this information to the ECU to
adjust the fuel/air mixture.

Throttle-Body Injection Unit

This is used on signal point injection
systems (only one injector). It includes
the injector, fuel pressure regulator,
throttle valve sensors and is known
as a Central Injection Unit.

Vacuum Limiter

Maintains a consistent pressure difference
either side of the throttle-valve. If the
pressure difference is exceeded,
additional air flows into the inlet manifold.

Warm up Regulator

Controls fuel quantity as the engine warms up.