Direct Petrol Injection System with Bosch Motronic MED 7 - Volkspage

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Fundamentals Stratified charge mode Among other things, several important conditions must be met before the engine management system can change over to stratified charge mode: - the engine is in the corresponding engine load and speed ranges - there are no exhaust emission faults in the system - the coolant temperature is above 50°C - the NOx sensor is ready, and - the temperature of the NOx storage catalyst is between 250°C and 500°C If the above conditions are met, the engine management system can change over to stratified charge mode. Intake process In stratified charge mode, the throttle valve is opened as wide as possible in order to minimise throttle losses. The intake manifold flap closes the lower duct in the cylinder head. The intake air flows at a faster rate and tumbles into the cylinders via the upper duct. Throttle valve Intake manifold flap Upper duct 253_037 The throttle valve cannot be opened completely as a certain vacuum must always be present due to the activated charcoal canister system and exhaust gas recirculation. Air flow In the cylinder, the tumble motion of the air is increased by the special shape of the piston crown. Tumble air Air flow Flow recess 10 253_038
<strong>Injection</strong> cycle Fuel is injected during the last third of the compression stroke. It begins approximately 60° before ignition TDC ends approximately 45° before ignition TDC. The injection point has a major role to play in the position of the atomised mixture in the area of the spark plugs. High-pressure Injector Fuel recess Flow recess 253_039 The fuel is injected in the direction of the fuel recess. The injector geometry is such that the atomised mixture disperses as required. 253_086 The fuel is transported towards the spark plugs by the fuel recess and the upward movement of the piston. This process is aided by the tumble motion of the air flow, which also transports the fuel to the spark plugs. The fuel mixes <strong>with</strong> the intake air on the way to the spark plugs. 253_086 11
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: Combustion process The term "combus
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 and 38: This is how it works Inlet with fin
Page 39 and 40: Activated charcoal canister system
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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