Chapter 9: Fuel injection systems

Returnless fuel injection systems

do not use fuel return line between the engine and the tank

diesel fuel injection

similar to gasoline injection, but requires higher injection pressure

cold start valve

to add extra fuel to the intake manifold when starting a cold engine

intake air heaters

to aid in igniting the compressed air-fuel mix during cold starting

manifold vacuum sensor

engine load is transmitted to the computer by means of an intake

turbine wheel

connected to the compressor wheel by a shaft

supercharger

consists of a drive belt and driven gears, and a centrifugal compressor wheel

engine control computer

constructed using many different electronic circuits and components

Intake manifold

part of the air induction system

Throttle body

part of the air induction system

control rack

plunger is connected, by means of a flange, to the toothed control sleeve that meshes

waste gate

controls the engine exhaust gas flow

Air cleaner assembly

part of the air induction system

Sensors

various engine functions and feed this information to the computer

Mechanical fuel injection

were the first and many years the only type of fuel injection

auxiliary air regulator

admits additional air into the intake manifold to increase the idle speed

Stoichiometric

air-fuel mixture will burn very cleanly with a minimum of pollutants

glow plugs

an electrically operated device that protrudes into the pre- combustion chamber

prechamber

at the precise time the piston has completed the compression stroke diesel fuel is sprayed into the combustion chamber

Non-timed fuel injections

at the same time or on an alternating basis

cetane number

comparing the burning characteristics

Spring pressure

forces the needle closed

delivery advance mechanism

fuel automatic

Continuous fuel injection

fuel pressure is controlled by an electronic control device or by an airflow metering valve

outward opening injectors

injector nozzle

inward opening injectors

injector nozzle heavy spring

Fuel rail

installed in the intake manifold and connected to the fuel system

Electronic fuel injection

made possible by the introduction of compact, durable, and inexpensive electronic components and computers for automotive use

Cone shaped pattern

maximum distribution and atomization

barometric pressure

measures the pressure of the outside air

engine speed sensor

monitors engine RPM

Oxygen sensors

monitors the amount of oxygen in the engine's exhaust gases

diesel injection pump

must be capable of producing high pressures

Sealing pintle

needle

Timed fuel injection

opened for only several milliseconds and is carefully timed to each cylinder

boost pressure

pressure delivered to the intake manifold controlled by the waste gate

fuel distributor

provides a constant pressure drop through the fuel distributor metering slots, a pressure regulating valve

octane

rating of gasoline

Pulse width

refers to the amount of time during which the injector electronic solenoid is energized, causing the injector to open

Water trap

removes any water from the fuel

viscosity compensator valve

tends to keep the injector pump functioning the same with either light or heavy fuels

airflow sensor

the amount of air entering the engine

compressor wheel

the belt drives the gear

Filter

the fuel delivery system

Nozzle

the fuel moves down through the injector until stopped

Pulse fuel injection

the injector may be opened and closed by electrical signals

Fuel injection

the process of spraying fuel directly into the engine

Atomizes

the spraying action of the injectors

throttle position sensor

throttle position is relayed to the computer

distributor injection pump

two types single and double

Direct fuel injection

used in diesel engines and few older gasoline engines

Indirect fuel injection

used in modern gasoline injection systems

fuel shutoff

used on diesel engines to stop the engine

speed density

uses a combination of the other sensors to determine air flow

incline injection pump

uses a separate cylinder plunger-cam for each cylinder

Throttle body fuel injections

uses an assembly containing one or two fuel injectors

turbocharger

uses the exhaust gases to drive a turbine wheel

Solenoid winding

when the injector is energized by the computer

Multiport fuel injection

when the system uses one injector per cylinder, the individual injector nozzles are located inside the intake manifold or in the cylinder head, close to the intake valve

Pressure Regulator

where the injection system pressure is controlled by

Throttle valve

which is opened and closed by the driver to control the amount of air entering the intake manifold

water in fuel sensor

will alert drivers to the fact that water is present in the fuel