Electronic Fuel Injection

ELECTRONIC PETROL INJECTION

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

Injector is switched off Intake manifold Inlet valve

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

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.

FUEL PUMP + - 10 11 1 2 3 4 5 6 7 8 9 PLEASE NAME THE PARTS OF THE FUEL PUMP

FUEL PUMP + - Fuel pump switched off

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.

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

FUEL PUMP + - Pump has now been switch off.

INJECTION SYSTEM WIRING LAYOUT Please complete the following wires into your work book, along with component names. Fuel pump Fuse Control relay 87 87b ECU M 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

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.

Fuel pressure gauge Reading now with 2 1 3 4 Fuel pressure gauge Reading now with Reading.............bar Vacuum pipe removed ........................bar

FUEL PUMP DELIVERY RATE 2 1 3 4 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

6. Record the reading for 15 seconds...................... 2 1 3 4 6. Record the reading for 15 seconds...................... EXAMPLE 540 cm 0.5 Ltr 19 fl oz

VIBRATION DAMPER

Please identify the following parts 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.

FUEL FILTER

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.

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

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.

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 ON THE NEXT SCREEN

To fuel tank From fuel rail Valve Diaphragm Spring Vacuum 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

To fuel tank From fuel rail Diaphragm Spring Valve Vacuum

Purpose of the vacuum connection To fuel tank From fuel rail Valve 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

To fuel tank From fuel rail Valve Diaphragm Spring High Vacuum 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

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

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

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 [ ]

FUEL INJECTOR

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.

FUEL INJECTOR Injector in the off position

FUEL INJECTOR Injector is switch on 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.

FUEL INJECTOR Injector has now been switched off

INJECTION SYSTEM WIRING LAYOUT Please complete the following wires into your work book, along with component names. Fuel pump Fuse Control relay 87 87b ECU M 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

INJECTOR TEST Injector OHMS

FUEL INJECTOR

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+ 12+

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

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.

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.

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.

FUEL INJECTOR WIRING TEST USING A TEST LAMP

COLD START INJECTOR

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.