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Presentation on theme: "Electronic Fuel Injection. ELECTRONIC PETROL INJECTION."— Presentation transcript:

1 Electronic Fuel Injection


3 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 Intake manifold Injector Inlet valve

5 Injector switched on Fuel is being delivered on top of the inlet valve.

6 + - 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.


8 + - FUEL PUMP Fuel pump switched off

9 + - FUEL PUMP Fuel pump is now operating, fuel is passing through the pump causing the check valve to open thus allowing fuel pressure into the system. Check valve open

10 + - FUEL PUMP 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 System Restriction

11 + - FUEL PUMP Pump has now been switch off.

12 COOLANT AIR THROTTLE AIR FLOW COLD START THERMO-TIME INJECTORS BATTERY SENSOR VALVE SWITCH FLOW METER VALVE SWITCH M b Control relay Ignition module Ignition switch ECU Fuel pump Fuse INJECTION SYSTEM WIRING LAYOUT Please complete the following wires into your work book, along with component names.

13 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.

14 Fuel pressure gauge Reading now with Reading bar Vacuum pipe removed bar

15 FUEL PUMP DELIVERY RATE 1. Disconnect fuel return pipe from the fuel pressure regulator. 2. Connect in it’s 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

16 Record the reading for 15 seconds EXAMPLE 540 cm 0.5 Ltr 19 fl oz


18 Please identify the following parts 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.


20 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.

21 FUEL FILTER 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 Please identify parts of the filter.

22 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.

23 To fuel tank From fuel rail Diaphragm Spring Valve Vacuum FUEL PRESSURE REGULATOR Rest position 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 ON THE NEXT SCREEN

24 To fuel tank From fuel rail Diaphragm Spring Valve Vacuum Regulator has opened due to an increase in pressure. The regulator will continue to open and close, to regulate system pressure

25 To fuel tank From fuel rail Diaphragm Spring Valve Vacuum

26 To fuel tank From fuel rail Diaphragm Spring Valve Vacuum Purpose of the vacuum connection The spring chamber of the pressure regulator is connected with the Plenum chamber by way of a hose. In this manner the fuel pressure or 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 To fuel tank From fuel rail Diaphragm Spring Valve High Vacuum The engine is at idle producing a high manifold depression. AIR SUPPLY TO THE ENGINE MANIFOLD DEPRESSION

28 To fuel tank From fuel rail Diaphragm Spring Valve Low Vacuum Throttle has been opened and the manifold depression has reduced

29 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

30 FUEL PRESSURE REGULATOR TEST 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 [ ] vacuum pump


32 FUEL INJECTOR 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.

33 FUEL INJECTOR Injector in the off position

34 FUEL INJECTOR If the magnet is excited and the nozzle needle is lifted off of it’s 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. Injector is switch on

35 FUEL INJECTOR Injector has now been switched off

36 COOLANT AIR THROTTLE AIR FLOW COLD START THERMO-TIME INJECTORS BATTERY SENSOR VALVE SWITCH FLOW METER VALVE SWITCH M b Control relay Ignition module Ignition switch ECU Fuel pump Fuse INJECTION SYSTEM WIRING LAYOUT Please complete the following wires into your work book, along with component names



39 FUEL INJECTOR PULSE TIMES ENGINE COLD ms % Degrees Cranking Idle ENGINE WARM Cranking Idle rpm rpm rpm Snap open throttle

40 INJECTOR SCOPE PATTERN A B C Please can you identify what is happening to the injector at A, B, and C

41 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.

42 FUEL INJECTOR DELIVERY TEST A, B, and D are correct C is not acceptable as it is more than 10% greater in delivery. A B C D

43 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.



46 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.

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