ELECTRONIC PETROL INJ

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Electronic Fuel Injection

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ELECTRONIC PETROL INJECTION
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ELECTRONIC PETROL INJECTION The motor industry is
trying to continue to reduce fuel emissions with
no loss in performance. This had become more and
more difficult with carburettors, they had become
very complex and expensive. The alternative has
been petrol injection, petrol injection will
deliver the exact amount of fuel for all engine
speeds and loads. Fuel is injected directly onto
the inlet valve,(multi-point systems) therefore
only air will flow in the inlet manifold and fuel
pressure is kept low making component cost less
than those found with diesel injection.
TYPES
OF SYSTEMS Based on Bosch K JETRONIC
Mechanical continuous injection KE
JETRONIC Electronic mechanical
continuous injection The following systems
operate their injectors intermittently all at
once D JETRONIC Pressure
sensing Druck (pressure) L,LE,LU,L3 JETRONIC
Air flow sensing Luft (air) LH JETRONIC
Hot wire measurement of air
mass MOTRONIC Fuel and
ignition management MONO JETRONIC
Single point injection SEQUENTIAL FUEL INJECTION
Injectors operate in the firing order
4
Injector is switched off
Injector
Intake manifold
Inlet valve
5
Injector switched on
Fuel is being delivered on top of the inlet valve.
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FUEL PUMP


The roller cell pump is driven
by a permanently
magnetic electric
motor. The periphery of the

rotating eccentric rotor plate has pocket shaped

openings, in each of which there
is a metal roller.
Centrifugal
force will move the rollers out, so that

they function as a circulating seal . The
pumping action is introduced by periodically
increasing the volume of the fuel feed and/or by
reducing the volume of the output. A safety
valve will connect the pressure and suction ends
when there is an abnormal increase in pressure.
A check valve in the pressure connection
provides the necessary supply pressure for when
the engine is restarted from hot. The valve will
close when the engine is turned off.
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FUEL PUMP
10
11
1 2 3 4
5 6 7 8
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PLEASE NAME THE PARTS OF THE FUEL PUMP
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FUEL PUMP

Fuel pump switched off
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FUEL PUMP
Check valve open

Fuel pump is now operating, fuel is passing
through the pump causing the check valve to open
thus allowing fuel pressure into the system.
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FUEL PUMP
System Restriction

Please note, if there is a restriction in the
system, a safety valve at the suction end of
the pump will open, thus causing a pressure
drop in the pump.
Safety valve has opened
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FUEL PUMP

Pump has now been switch off.
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INJECTION SYSTEM WIRING LAYOUT
Please complete the following wires into your
work book, along with component names.
Control relay
Fuel pump Fuse
87 87b
M
ECU
50 31 1 15 30
1 4
-
1 15
Ignition module
Ignition switch
COOLANT AIR THROTTLE AIR FLOW
COLD START THERMO-TIME
INJECTORS BATTERY SENSOR
VALVE SWITCH FLOW METER
VALVE SWITCH
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FUEL PRESSURE TEST
1. Disconnect the fuel supply to the fuel
rail. 2. Connect pressure gauge to high pressure
fuel line. 3. Start the engine and note the
reading in bar. 2 to 3 bar multi-point injection
systems 1 to 1.5 bar single point injection
systems 4. Disconnect the vacuum pipe to the
pressure and record the reading in bar.
Note! this does not apply to systems with fuel
fuel pressure regulators not fitted with
vacuum pipes.
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Fuel pressure gauge Reading now
with Reading.............bar Vacuum pipe
removed
........................bar
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FUEL PUMP DELIVERY RATE
1. Disconnect fuel return pipe from the fuel
pressure regulator. 2. Connect in its place a
pipe and direct the pipe into a measuring
vessel. 3. Remove the fuel pump relay. 4.
Connect across terms 30/88 and 87 a jump
wire. 5. Switch on the ignition and operate the
fuel pump for 15 seconds
pto
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6. Record the reading for 15 seconds............
.......... EXAMPLE 540 cm 0.5
Ltr 19 fl
oz
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VIBRATION DAMPER
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VIBRATION DAMPER
Please identify the following parts
2
1 3 4 5 6
1
Because of pressure variations in the fuel
system, a pulsation damper is fitted into
the fuel line between the fuel pump and the fuel
filter. This reduces noise resulting in pressure
variations created by the injectors and pressure
regulator.
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FUEL FILTER
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FUEL FILTER
The filter has an arrow on it,s body, this
indicates the way it is fitted to the fuel
system. The arrow shows direction of flow
from the fuel tank.
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FUEL FILTER
Please identify parts of the filter.
1 2 3
Paper cartridge with a seperation mesh of 8 to 10
Micron and a surface area of 3000cm
squared. The direction of flow is shown by the
arrows
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FUEL PRESSURE REGULATOR
The fuel pressure regulator keeps the fuel
pressure constant, regardless of the delivery and
ejected volume of fuel. The excessive fuel will
flow back to the tank via a return line, so that
there will be cool and vapor lock free fuel for
the injection valves.
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FUEL PRESSURE REGULATOR
To fuel tank
Rest position
From fuel rail Diaphragm Spring
Valve
Vacuum
The spring will control the pressure of the
system, when the fuel pressure increases the it
will exert a downward force on the diaphragm,
thus opening the return valve to the tank. AS
SEEN ONTHE NEXT SCREEN
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Regulator has opened due to an increase in
pressure. The regulator will continue to open and
close, to regulate system pressure
To fuel tank
From fuel rail Diaphragm Spring
Valve
Vacuum
25
To fuel tank
From fuel rail Diaphragm Spring
Valve
Vacuum
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Purpose of the vacuum connection
To fuel tank
From fuel rail Diaphragm Spring
Valve
Vacuum
The spring chamber of the pressure regulator is
connected with the Plenum chamber by way of a
hose. In this manner the fuel pressure 2.5 or
- 0.2 bar will be influenced to a degree
depending on the intake manifold depression. The
difference between injection pressure and intake
pressure will always remain constant and the
volume of fuel injected from the injection
valves will only depend on opening period.
NOTE THE OPERATION ON THE NEXT SCREENS
27
The engine is at idle producing a high manifold
depression.
To fuel tank
From fuel rail Diaphragm Spring
Valve
High Vacuum
AIR SUPPLY TO THE ENGINE
MANIFOLD DEPRESSION
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Throttle has been opened and the manifold
depression has reduced
To fuel tank
From fuel rail Diaphragm Spring
Valve
Low Vacuum
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FUEL PRESSURE REGULATOR TEST
1. Disconnect vacuum pipe from pressure
regulator. 2. Remove fuel pump relay and fit by
pass cable. 3. Record fuel pressure...............
bar
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FUEL PRESSURE REGULATOR TEST
vacuum pump
4. Connect a vacuum pump to the pressure
regulator. 5. Apply a vacuum of 0.5 bar. 6.
Record fuel pressure.................bar NOTE
Pressure should drop by about 0.5 bar. 7. turn
off the fuel pump, pressure should hold. TICK
BOX Yes No
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FUEL INJECTOR
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FUEL INJECTOR
7 6 5
4 3 2 1
An electro magnetic injection valve (or fuel
injector) is located in the intake port
immediately in front of the intake valve of
each cylinder. These injection valves are
connected parallel and inject fuel
simultaneously once for each turn of the
crankshaft.
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FUEL INJECTOR
Injector in the off position

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FUEL INJECTOR
Injector is switch on
If the magnet is excited and the nozzle needle is
lifted off of its seat by approx. 0.15mm, the
fuel can be let out through the calibrated
annular gap at the existing pressure. The fine
atomization is caused by a ground spraying
pintle at the front end of the nozzle needle. The
lifting and dropping times of the valve are less
than 1ms the opening time between 2 and 10ms.
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FUEL INJECTOR
Injector has now been switched off
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INJECTION SYSTEM WIRING LAYOUT
Please complete the following wires into your
work book, along with component names.
Control relay
Fuel pump Fuse
87 87b
M
ECU
50 31 1 15 30
1 4
-
1 15
12 13
Ignition module
Ignition switch
COOLANT AIR THROTTLE AIR FLOW
COLD START THERMO-TIME
INJECTORS BATTERY SENSOR
VALVE SWITCH FLOW METER
VALVE SWITCH
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INJECTOR TEST
Injector
OHMS
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FUEL INJECTOR
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FUEL INJECTOR PULSE TIMES
ENGINE COLD ms
Degrees Cranking 4
6.66 3.99 Idle
4 6.66
3.99 ENGINE WARM Cranking
2.2 3.74 2.25 Idle
2.5 3.74
2.24 1000 rpm 2.4
4 2.40 2000 rpm
2.3 7.66 4.59 3000
rpm 2.2 11.00
6.60 Snap open throttle 6 20
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INJECTOR SCOPE PATTERN
A B C
Please can you identify what is happening to the
injector at A, B, and C
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FUEL INJECTOR DELIVERY TEST
Position the injection valves over a suitable
containers . Briefly operate the starter motor
and check that an even cone shaped spray is
delivered from each injector.
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FUEL INJECTOR DELIVERY TEST
A B C D
A, B, and D are correct C is not acceptable as it
is more than 10 greater in delivery.
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FUEL INJECTOR LEAK RATE TEST
With the injector valves positioned over the
containers. Turn on the ignition for 5 seconds.
No more than 2 drops of fuel per minute should
leak from each injector.
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FUEL INJECTOR WIRING TEST USING A TEST LAMP
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COLD START INJECTOR
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COLD START INJECTOR CIRCUIT
Only operates during cranking when the engine is
cold for a period of up to 8 seconds.
The injector gets it,s earth through the thermal
time- switch. Inside of the switch is a bi-metal
strip and heater coil. When the injector is
operated during cranking the heater coil heats
the bi-metal strip which will bend and break the
earth of the cold start valve.