Direct Petrol Injection System with Bosch Motronic MED 7 - Volkspage

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Engine management Fuel metering valve (N290) It is located in the supply line leading to the highpressure fuel pump and the fuel pressure regulator. It is attached to the suspension strut tower. Fuel metering valve Task 253_049 During normal operation, the valve is open and releases the path to the fuel pressure regulator. A hot start occurs when the coolant temperature is higher than 110°C and the intake air temperature is higher than 50°C at engine startup. In this case, the valve is activated by the engine control unit for approx. 50 seconds and closes off the path to the fuel pressure regulator. As a result, the pressure in the low pressure fuel system rises to the maximum feed pressure of the electric fuel pump, which is limited to 5.8 bar by an internal pressure limiting valve. This pressure increase prevents vapour bubbles from forming on the suction side of the highpressure fuel pump and allows a high pressure to build up safely. <strong>Motronic</strong> control unit (J220) Intake air temperature sender (G42) Coolant temperature sender (G62) High-pressure fuel pump Electric fuel pump (G6) <strong>with</strong> pressure limiting valve Fuel metering valve (N290) Fuel pressure regulator (low pressure) 253_113 Failure strategies If the fuel metering valve fails, it is kept closed by a pressure spring. As a result, the pressure in the low pressure fuel system rises to 5.8 bar to prevent a vehicle breakdown during the hot start. 38
Activated charcoal canister system This is necessary in order to meet the statutory requirements relating to hydrocarbon emissions (HC). It prevents fuel vapour from escaping the fuel tank to the surrounding atmosphere. Fuel vapour is stored in the activated charcoal canister and burned off at periodic intervals. In homogeneous lean charge mode and in homogeneous charge mode, the ignitable mixture is evenly distributed inside the combustion chamber. So the combustion process takes place in the whole of the combustion chamber. The fuel discharged from the activated charcoal canister system is also burned. In stratified charge mode, the ignitable mixture is present only in the area of the spark plugs. However, a portion of the fuel from the activated charcoal canister system is located in the non-ignitable outer region. This can lead to incomplete combustion and an increase in HC emissions in the exhaust gas. For this reason, stratified charge mode is only allowed if a low activated charcoal canister load is calculated. The engine control unit calculates how much fuel may be fed from the activated charcoal canister system. Then the solenoid valve is activated, the injection quantity is adapted and the throttle valve is adjusted. N30 -33 N80 J220 G70/G42 G28 G39 As a result, the engine control unit requires the following information: J338 - the engine load from the hot-film air mass meter (G70) - the engine speed from the engine speed sender (G28) - the intake air temperature from the intake air temperature sender (G42), and - the load state of the activated charcoal canister from the lambda probe (G39) 253_077 39
Page 1 and 2: Service. Self-Study Programme 253 D
Page 3 and 4: Table of Contents Introduction . .
Page 5 and 6: Why has Volkswagen waited until now
Page 7 and 8: Homogeneous operation at high exhau
Page 9 and 10: Combustion process The term "combus
Page 11 and 12: Injection cycle Fuel is injected du
Page 13 and 14: Homogeneous lean charge mode This i
Page 15 and 16: Mixture formation process By inject
Page 17 and 18: Motronic control unit J220 Fuel pum
Page 19 and 20: Torque-based engine management syst
Page 21 and 22: Intake system In comparison with th
Page 23 and 24: This is how it works The driver inp
Page 25 and 26: Intake manifold flap actuated In st
Page 27 and 28: Air-mass flow meter G70 and intake
Page 29 and 30: This is how the exhaust gas recircu
Page 31 and 32: Fuel system The fuel system is divi
Page 33 and 34: This is how it works The fuel flows
Page 35 and 36: The fuel pressure regulating valve
Page 37: This is how it works Inlet with fin
Page 41 and 42: Exhaust system This was adapted to
Page 43 and 44: Broadband lambda probe (G39) The br
Page 45 and 46: Exhaust gas temperature sender (G23
Page 47 and 48: NOx sensor control unit (J583) This
Page 49 and 50: Function of the NOx sender The func
Page 51 and 52: Sulphur regeneration is a technical
Page 53 and 54: Variable valve timing Inner exhaust
Page 55 and 56: Positive terminal GND Input signal
Page 57 and 58: Notes 57 Solutions to questions on
Page 59 and 60: 5. What is the signal from the inta

Direct Petrol Injection System with Bosch Motronic MED 7 - Volkspage

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