Audi 4.2-litre V8 FSI Service Training Download Page 35 | Manualshive

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The basic engine in Q7 and the high-revving engine
in RS4 have different fitting locations for the
secondary air system. In the Q7 the secondary air
system is fitted at the engine front end on the input
side of the ribbed vee belt, while in the RS4 it is
fitted at the output end of the engine.

377_074

Reference

For an exact description of the operating
mode this system, please refer to
SSP 217 - The V8 5V Engine.

Operating mode in the RS4

The secondary air system operates in much the
same way as that in the Q7 engine. The difference
here lies in the way the combination valves open
and close.

The air path from the secondary air pump to the
secondary air duct in the cylinder head is opened by
means of a vacuum unit on the combination valve.
The vacuum unit is controlled by the secondary air
inlet valve N112 via the engine control unit.

Air filter

Secondary air pump

Combination valve with vacuum unit
(vacuum controlled)

Secondary air
injection valve N112

Secondary air system RS4

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Summary of Contents for 4.2-litre V8 FSI

Page 1: ...Audi 4 2 litre V8 FSI engine Self Study Programme 377 Service Training ...

Page 2: ......

Page 3: ...rsion for the new RS4 A V10 engine with 5 2 litres of displacement will also be available Like the RS4 engine the V8 in the Q7 has FSI direct injection which following five victories in the Audi R8 Le Mans racing car is now being introduced in a production eight cylinder model The V8 was retuned for use in the Audi Q7 A fuller torque curve up to nominal speed and spontaneous response these are the...

Page 4: ...n 12 Chain drive 14 Drive ancillary units 15 Cylinder head 16 Design 18 Oil pump and oil filter module 19 Oil pan Audi RS4 20 Oil circuit 21 Cooling system in Audi Q7 22 Cooling system in Audi RS4 23 Air intake 24 Intake manifold flaps 24 Vacuum hoses in the Audi RS4 26 Vacuum hoses in the Audi Q7 28 Introduction 6 Specifications 8 ...

Page 5: ... programme teaches the basics of the design and function of new models new automotive components or new technologies The self study programme is not a Repair Manual All values given are intended as a guideline only and refer to the software version valid at the time of publication of the SSP For maintenance and repair work always refer to the current technical literature Note Reference Exhaust sys...

Page 6: ...et for the development of the Q7 engine High specific engine power 257 kW 350 bhp out of 4 2 litres 15 bhp more than MPI engines High torque 440 Nm out of 4 2 litres Reduction of fuel consumption by approx 5 360 g kWh at 2000 rpm and 2 bar Short and compact design Modular engine concept based on V6 FSI engine for V8 and V10 FSI synergy High idling quality High standard of comfort with regard to ac...

Page 7: ...ium variable inlet manifold with integrated tumble flap not fitted in RS4 Drive by wire throttle control for compliance with exhaust emission standards EU IV LEV II The main technical differences between the base engine and the high revving engine lie in the following modules Cranktrain Timing gear Cylinder head Oil supply Engine cooling Intake path Exhaust system Engine management For an exact de...

Page 8: ... engine V8 90 vee angle 4V FSI Displacement in cm3 4163 Max power output in kW bhp 257 350 at 6800 rpm 309 420 at 7800 rpm Max torque in Nm 440 at 3500 rpm 430 at 5500 rpm Number of valves per cylinder 4 Bore in mm 84 5 Stroke in mm 92 8 Compression ratio 12 5 0 4 1 Firing order 1 5 4 8 6 3 7 2 Engine weight in kg approx 198 approx 212 Engine management Bosch MED 9 1 1 Bosch 2x MED 9 1 Fuel grade ...

Page 9: ...n alloy is hypereutectic and has a silicon content of 17 AlSi17Cu4Mg The cylinder crankcase underwent special heat treatment in order to increase its strength The cylinder liners are mechanically stripped The cylinder crankcase of the high revving engine was machined to higher specifications due to the higher stresses in this component To minimise warping of the cylinder manifolds the crankcase is...

Page 10: ...end bearing Ø 54 mm Big end bearing width 15 25 mm Modifications to high revving engine At the very high engine speeds axial vibration occurs due to the unbalance in the single mass damper This can cause the crankshaft to break To avoid this vibration a dual mass damper without unbalance is employed in the high revving engine To compensate for unwanted engine vibration heavy metal inserts are inte...

Page 11: ...t con rods in the RS4 engine are made of 34CrNiMo8 for strength In addition the geometry of the con rods was reduced for the high revving engine and the toler ances were reduced Bearing journals Ø 54 mm Bearing bushings 1 4 mm thick 15 25 mm wide Length of bushing Ø 20 mm rolled Con rod length 154 mm Cracking During the cracking process the con rod is split at a predetermined breaking point using ...

Page 12: ...This inlet point is integrated in the coolant circula tion system and heated This prevents the crankcase breather from freezing up Engine mechanicals Crankcase ventilation The crankcase is ventilated through both cylinder heads The valve hoods incorporate a large settling space This space acts as a gravity type oil separator A fine oil separator is connected to the valve hoods by means of plastic ...

Page 13: ...untreated but the remainder is optimally treated by the cyclones The separated oil is collected in an oil reservoir beneath the cyclones The oil cannot drain out of the reservoir until the oil drain valve is opened The oil drain valve is closed as long as the pressure in the crankcase i e below the valves is higher than in the oil separator The valve opens auto matically due to gravity only at ver...

Page 14: ...d the reduction ratios in drives A B and C The load on the roller chains was reduced in the basic engine version by selecting a higher number of teeth Illustration shows the Q7 engine Q7 The camshafts in the basic engine are driven by 3 8 simplex roller chains Due to their acoustic advantages the chains were developed to meet the high comfort requirements In this case the idler gears have 40 and 2...

Page 15: ...ump and the compressor are driven by chain drive D The chain is driven directly by the crankshaft deflected by an idler gear and drives the chain sprocket seated on the gear module Chain drive D Power steering pump Coolant pump Gear module Air conditioner compressor Oil pump ...

Page 16: ... revving engine To match the higher engine power output and RPM the following cylinder head components were modified Intake ports are charge optimised based on larger cross sections Intake valves are chrome plated hollow stem valves for weight reduction Valve springs are made of a material with higher tensile strength and also have higher spring force To meet the higher fuel requirements the injec...

Page 17: ...17 377_015 377_080 High pressure fuel pump with fuel metering valve Crankcase breather Valve hood Hall sensor Assembled camshafts Exhaust adjuster with return spring Intake adjuster ...

Page 18: ... improve fuel economy The baffle plate is designed such that it not only prevents the crankshaft churning the oil in the sump but also strengthens the main bearing walls In the basic engine the oil is cooled by an oil water heat exchanger In the more highly stressed high revving engine an additional oil air heat exchanger is used to mini mise the oil temperature even at high engine load This addit...

Page 19: ... side Oil filter module The oil filter module is designed as a full flow filter For easy maintenance it is accommodated in the inner vee of the engine The filter element can be easily replaced without the need for special tooling It is made of a polymer based nonwoven material Return line from the engine Bottom filter on intake side Polymer based nonwoven filter element Sealing cap from the pressu...

Page 20: ...axis of vehicle are arranged inside a housing Each of the flaps opens towards the inside of the intake end of the oil pump Function When the vehicle is cornering the oil flows inside the sump towards the outside of the corner The two flaps facing the outside of the corner close and hold the oil in the sump intake At the same time the two flaps facing the inside of the corner open to allow addition...

Page 21: ...21 Oil circulation system 377_059 Pressurised oil downstream of filter Pressurised oil upstream of filter ...

Page 22: ...n the basic engine When operating at full throttle the coolant tempera ture is reduced to 90 C via an electrically heated thermostat to avoiding increasing the tendency of the engine to knock When operating at part throttle which is not critical with regard to knock the coolant temperature is increased to 105 C The thermodynamic advantages and the reduced friction result in a fuel saving of approx...

Page 23: ... used Coolant flows continuously through one of the additional coolers The second additional cooler is opened via a cool ant thermostat To avoid excessive heating up after shutting off the hot engine the coolant run on pump is activated a preset period of time after the engine is shut off The pump run on time and the need for additional activation of both radiator fans are determined on the basis ...

Page 24: ...t manifold the intake mani fold flaps in both engine variants are controlled according to a characteristic map In both engines the intake manifold flaps are activated in the lower engine load and RPM ranges They are brought into abutment with the port baffles in the cylinder head and thereby seal the lower part of the intake port The aspirated air mass now flows through the upper section of the in...

Page 25: ...ened and closed by a vacuum actuator which is map controlled by the engine control unit via the variable intake manifold change over valve N335 The sand cast aluminium intake manifold was designed specially to match the sporty characteris tic of the engine In contrast to the basic engine maximum torque is produced at higher engine RPM At this engine speed the intake manifold change over valve woul...

Page 26: ...turn valve Air filter Filter housing flap B A Brake servo relay J569 This means that connecting a vacuum line down stream of the throttle valve would offer little pros pect of success because in many engine operating situations the wide open throttle valve would result in low mass flow rates and vacuum in the intake manifold being Vacuum hoses in the Audi RS4 Vacuum reservoir Brake servo Suction j...

Page 27: ...tion jet pump An extreme case is that of cold starting For example when the catalytic converter is heating up the throttle valve is wide open Engine control unit master J623 Engine control unit 2 slave J624 B A Exhaust flap In this case the vacuum produced by the suction jet pump is not enough to sufficiently evacuate the brake servo The brake servo pressure sensor G294 is connected to the line to...

Page 28: ...condary air pump Brake servo Air filter Brake servo relay J569 Vacuum pump for brakes V192 Evaporator casing extraction valve Brake servo pressure sensor G294 Combination valve Suction jet pump entrainment pump with non return valve Engine control unit J623 A ...

Page 29: ...29 377_068 Note The illustrations show the vacuum hoses The fitting locations may deviate from those shown here Secondary air pump relay J299 Evaporator casing from fuel tank ...

Page 30: ...stem is that it has high pressure pumps Fuel system Fuel system in the Audi Q7 RS4 Leakage line Fuel filter Fuel pressure sender low pressure G410 Fuel metering valve N290 High pressure fuel pump 2 Fuel metering valve 2 N402 High pressure fuel pump 1 Low pressure system in the Audi RS4 High pressure Low pressure depressurised Low pressure system in the Audi Q7 ...

Page 31: ...ibutor rail 1 to the injectors of cylinders 5 8 N83 N86 Injectors cylinders 1 4 N30 N33 Fuel pressure sender high pressure G247 Fuel distributor rail 2 Return line Fuel pump control unit J538 Fuel tank Fuel pump pre supply pump G6 Pressure limiting valve 136 bar ...

Page 32: ...and right exhaust pipes are clearly separated Likewise the rear silencer is an absorption type silencer Exhaust system Audi RS4 To enhance the sporty character of the RS4 engine a fan type manifold is used in the RS4 Good separation of the exhaust pulses is ensured by keeping the individual exhaust pipes apart until they merge into one These fan type manifolds are also attached by means of the cla...

Page 33: ...on The exhaust gas flaps are closed at idle low engine load and at low engine RPM Function The exhaust flaps are switched by a vacuum actuator Both vacuum units are switched by an electrically activated solenoid valve The exhaust flaps are switched according to a characteristic map The factors of engine load engine RPM gear selected and the shift signal from the Sport button are used to plot the c...

Page 34: ...that the catalytic converter heats up more quickly and is available sooner after a cold start Principle Due to the richer air fuel mixture in the cold start and warm up phases a higher concentration of unburned hydrocarbons occurs in the exhaust gas Post oxidation in the manifold and headpipe is promoted by secondary air injection The heat dissipated during this process heats the catalytic convert...

Page 35: ...SP 217 The V8 5V Engine Operating mode in the RS4 The secondary air system operates in much the same way as that in the Q7 engine The difference here lies in the way the combination valves open and close The air path from the secondary air pump to the secondary air duct in the cylinder head is opened by means of a vacuum unit on the combination valve The vacuum unit is controlled by the secondary ...

Page 36: ...valve module J338 Throttle valve drive angle senders 1 and 2 electric power control G187 G188 Lambda probe G39 Lambda probe 2 G108 Lambda probe after catalytic converter G130 Lambda probe after catalytic converter 2 G131 Coolant temperature sender radiator outlet G83 Brake light switch F Brake pedal switch F47 Brake servo pressure sensor G294 Additional signals Cruise control system on off from st...

Page 37: ...iming adjustment valves 1 2 N205 N208 Exhaust camshaft timing adjustment valves 1 2 N318 N319 Lambda probe heater Z19 Lambda probe 2 heater Z28 Lambda probe 1 heating after catalytic converter Z29 Lambda probe 2 heating after catalytic converter Z30 Variable inlet manifold motor V183 Intake manifold flap motor V157 Continued coolant circulation relay J151 Coolant run on pump V51 Additional signals...

Page 38: ...e light switch F Brake pedal switch F47 Hall sender 2 G163 Hall sender 4 G301 Knock sensors 1 2 G61 G66 Coolant temperature sender G62 Intake manifold flap potentiometer G336 Additional signals Cruise control system on off Terminal 50 Door contact wake up from convenience system central control unit J393 Lambda probe 2 G108 Lambda probe after catalytic converter 2 G131 Intake manifold flap potenti...

Page 39: ...le J338 Electro hydraulic engine mounting solenoid valve right N145 Inlet camshaft timing adjustment valve 1 N205 Exhaust camshaft timing adjustment valve 1 N318 Continued coolant circulation relay J151 Coolant run on pump V51 Lambda probe 1 heater Z19 Lambda probe 1 heating after catalytic converter Z29 Variable intake manifold change over valve N335 Brake servo relay J569 Vacuum pump for brakes ...

Page 40: ...r is used in the RS4 engine with master slave concept The signal from the Hall sender can unlike the signal from the inductive sender be split with the result that it can be utilised by both engine control units Applying the signal directly to both engine control units ensures that the control units are absolutely in sync Throttle valve module The Bosch throttle valve module used in the Q7 is the ...

Page 41: ...plied to the encoding pin the control unit is the master Control unit 1 master Control unit 2 slave Private bus CAN data bus Operating modes Start high pressure stratified charge start Injection of the metered fuel mass begins during the compression stroke phase and ends shortly before the firing point After start HOSP homogeneous split Application Heating the primary catalytic converters to 300 C...

Page 42: ...ation Brake pedal switch CCS switch positions CCS set speed SET ACTUAL idle speed Throttle valve angle Intake air temperature Drive by wire throttle lamp OBD2 lamp Hot warning lamp Power reduction or air conditioner compressor load shedding Fuel consumption Radiator fan activation Oil temperature Fault memory entry Activation of electrical brake servo pump Automatic gearbox control unit J217 Trans...

Page 43: ... Engine torque Engine speed Coolant temperature Brake light switch information CCS status Throttle valve angle Intake air temperature OBD2 lamp Hot warning lamp Air conditioner compressor OFF or power reduction Starter control automatic start Oil temperature Steering angle sender G85 Steering wheel angle and steering wheel angle speed utilised for idle pre control and engine torque calculation bas...

Page 44: ...pedal has left its rest position and opens The F194 is actuated i e closed when the clutch is fully depressed Because one switch opens and the other closes the engine control unit can verify the redundancy of both switches The cruise control system also utilises the signal from the F36 When a repeat attempt is made to start the e g stalled engine the ignition key does not have to be turned back Th...

Page 45: ... S 377_076 G28 Engine speed sender J53 Starter motor relay J623 Engine control unit master J624 Engine control unit 2 slave J695 Starter motor relay 2 Legend of function diagram B Starter D Ignition switch E378 Starter button F36 Clutch pedal switch F194 Clutch pedal switch for engine start ...

Page 46: ...e is deactivated when the ignition is turned off Accelerator position When the Sport program button is pressed the following in vehicle functions are activated more direct accelerator pedal response improved lateral support function of the driver s seat more sporty exhaust system set up Normal operation Sport mode Requested torque in Accelerator pedal function throttle progression When Sport mode ...

Page 47: ...are deflated approx two sec The sport seat function can be deactivated by the driver as necessary The procedure is described in the vehicle s Owner s Manual Exhaust flap control After the Sport mode is activated unlike in normal operation the exhaust flaps in the rear silencer are opened when the engine is idling This emphasises the sporty sound of the RS4 engine After the engine speed is increase...

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