Self Study Programme 607 For internal use onlyAudi 4.0l V8 TFSI engine with biturbo chargingAudi Service TrainingAudi has a new addition to its family of V engines. The 4.0l V8 TFSI is the first eight-cylinder petrol engine to feature twin exhaust turbocharging and FSI technology. The engine is based on the 4.2l V8 FSI naturally aspirated engine of the Audi A8 ’12. The basic engine derives largely from the 4.2l V8 FSI. To improve fuel economy, the displacement was reduced to 4.2 litres from 4.0 litres. Another "active" measure for reducing displacement is "cylinder on demand". This system allows the engine to operate more efficiently at partial load. Another key feature is the HSI (Hot Side Inside) configuration. For this purpose, both exhaust turbochargers are integrated in the inside V of the cylinder block. Even the charge air cooler is housed here. One of the major development challenges was finding space for the engine in the engine bay.Firstly, the heat generated under the bonnet by the HSI configuration had to be taken into consideration. On the other hand, the statutory regulations concerning pedestrian safety had to be met. The engine has a wide range of power outputs to accommodate various Audi models. Furthermore, other Group brands also use this unit in their models. The 4.0l V8 TFSI engine employs all the technologies from Audi’s modular efficiency platform. These range from the start-stop system and the recuperation system to a broad array of frictionreducing measures. The V8 is assembled at Audi’s Hungarian plant in Györ using high-end technologies such as "plate honing".607_006In this Self Study Programme you will learn about the technology of the 4.0l V8 TFSI engine. When you have worked your way through this Self Study Programme, you will be able to answer the following questions: • How is the basic engine designed? • How do the engine systems (e.g. air supply, oil supply, cooling) work?2• What does cylinder on demand do and how is this implemented? • What are the special features of the 2nd generation thermal management system? • What aspects of the engine management system have changed compared to the 4.2l V8 FSI engine? • What are the points to note when servicing the vehicle?ContentsIntroductionEight cylinders symbolised by four rings _________________________________________________________________________________________________________________ 4 Brief technical description _________________________________________________________________________________________________________________________________ 6 Specifications ________________________________________________________________________________________________________________________________________________ 8Engine mechanicalsCylinder block ______________________________________________________________________________________________________________________________________________ 12 Cranktrain ___________________________________________________________________________________________________________________________________________________ 16 Crankcase ventilation ______________________________________________________________________________________________________________________________________ 18 Activated charcoal filter (ACF) system ___________________________________________________________________________________________________________________ 23 Cylinder heads ______________________________________________________________________________________________________________________________________________ 24 Chain drive __________________________________________________________________________________________________________________________________________________ 26 Auxiliary units drive ________________________________________________________________________________________________________________________________________ 27Oil supplyOverview ____________________________________________________________________________________________________________________________________________________ 28 Oil pump ____________________________________________________________________________________________________________________________________________________ 30 Oil cooling __________________________________________________________________________________________________________________________________________________ 33 Oil filter _____________________________________________________________________________________________________________________________________________________ 34 Oil pressure monitoring ___________________________________________________________________________________________________________________________________ 36 Switchable piston cooling jets ____________________________________________________________________________________________________________________________ 38Cooling systemSystem overview ___________________________________________________________________________________________________________________________________________ 44 Engine circuit and cooling module _______________________________________________________________________________________________________________________ 48 Gear oil cooling/heating ___________________________________________________________________________________________________________________________________ 50 Charge air cooling __________________________________________________________________________________________________________________________________________ 53 Heating circuit ______________________________________________________________________________________________________________________________________________ 54 Radiator layout _____________________________________________________________________________________________________________________________________________ 54Air supply and chargingOverview ____________________________________________________________________________________________________________________________________________________ 56 Twin-scroll exhaust turbocharger ________________________________________________________________________________________________________________________ 58cylinder on demandIntroduction ________________________________________________________________________________________________________________________________________________ 62 Function _____________________________________________________________________________________________________________________________________________________ 64 Active engine mounting system __________________________________________________________________________________________________________________________ 68 Active noise cancelation (ANC) ___________________________________________________________________________________________________________________________ 72Fuel systemOverview ____________________________________________________________________________________________________________________________________________________ 76Exhaust systemOverview ____________________________________________________________________________________________________________________________________________________ 78 Exhaust valves ______________________________________________________________________________________________________________________________________________ 80 Secondary air system ______________________________________________________________________________________________________________________________________ 82Engine management systemSystem overview ___________________________________________________________________________________________________________________________________________ 84 MED 17.1.1. engine management system ______________________________________________________________________________________________________________ 86AnnexService _______________________________________________________________________________________________________________________________________________________ 88 Test your knowledge _______________________________________________________________________________________________________________________________________ 90 Self Study Programmes ___________________________________________________________________________________________________________________________________ 91The Self Study Programme teaches a basic knowledge of the design and functions of new models, new automotive components or new technologies. It is not a Repair Manual! Figures are given for explanatory purposes only and refer to the data valid at the time of preparation of the SSP. For further information about maintenance and repair work, always refer to the current technical literature.NoteReference3IntroductionEight cylinders symbolised by four ringsHigh-performance eight cylinder engines have long been a staple of Audi's product portfolio. They reflect the brand’s premium status particularly in the segment of high-performance and sporty luxury-class saloons. However, V8 engines are also available as options in Audi’s sports cars and SUVs. The origins of eight-cylinder engines bearing the four-rings of the Audi badge go back much further. Development of the first eightcylinder engines began at Horch-Werke, a brand affiliated to Auto Union, which later became Audi AG.1927 – Germany's first eight-cylinderThe Horch 303 by Horch-Werke of Zwickau was the company’s first luxury-class straight-eight engine. Production began in January 1927, and it was the first successful German production car with an eight-cylinder engine. The straight-eight engine with double overhead camshafts was designed by Paul Daimler, son of Gottfried Daimler. Even the most basic version of this model, an open tourer, rated among the top luxury vehicles in Germany. An impressive 8490 units of this double-camshaft engine were produced before production ended in 1931. The Horch eight-cylinder was noted for its particularly smooth running. Apparently, the engine ran so smoothly, a coin would stay balanced on edge on it while it was running.607_1031933 – Horch launches its first V8 engineIn 1933, Auto Union presented a Horch with V8 engine for the first time at the Berlin Motor Show. It had a cubic capacity of 3 litres. Because of its number of cylinders and displacement, the "little" Horch was designated Type 830. Continuing the Horch V8 model series, the Horch 830 BL was launched in 1935 on a long- wheelbase chassis. In terms of numbers, this was one of the most successful products of the Horch factory. Fifty percent of the total of 6,124 units built were Pullman saloons (see illustration).607_104 41988 – Entry into the automotive luxury classThe Audi V8 was presented to the public at the 1988 Paris Motor Show. The vehicle was built at the Neckarsulm plant. The V8 was the only saloon vehicle in the luxury class to be able to boast permanent four-wheel drive. The V8 engine initially had a displacement of 3562 cm³ and developed 185 kW at 5800 rpm. It was followed by a version with a displacement of 4.2 litres, which was also used in the successor model, the Audi A8. The V8 marked Audi’s entry into the automotive luxury class. Production of the Audi A8 ended after six years early in the summer of 1994. In the early 1990's, Audi made a successful foray into the German Touring Car Championship with its V8, winning two championship titles. For more information, please refer to Self Study Programme 106 "Audi V8" and Self Study Programme 217 "The V8 5V engine".607_1052006 – FSI direct injectionTo utilise the potential of direct fuel injection for its V8 engines, Audi equipped the 4.2l V8 engine with FSI petrol direct injection. The engine was available in two versions - a comfort-oriented basic version (used for the first time in the Audi Q7) and a sporty highrevving version for the Audi RS4 ’06 (309 kW at 7800 rpm). The V8 was reconfigured for use on the Audi Q7 (257 kW at 6800 rpm). Characteristics of this new engine included a fuller torque curve up to maximum rated speed and immediate throttle response. The engine excelled not only with its dominant power output and high torque. The resultant driving performance was excellent, and stood up well against the tough competition. For further information, please refer to Self Study Programme 377 "Audi 4.2-litre V8 FSI engine".607_1062012 – Turbocharging and cylinder on demandThe 4.0l V8 TFSI is the first Audi eight-cylinder petrol engine to feature twin exhaust turbocharging and FSI technology. There are multiple versions of this engine, which are used in various models of the Audi C and D series. The main focus of development was on reducing fuel consumption - and this was achieved by a number of measures, such as cylinder on demand. You will find a detailed description of this engine in this self study programme.607_107 5Brief technical description• Eight cylinder V engine with 90° bank angle • FSI petrol direct injection • Cast aluminium cylinder block • Biturbo charging with twin-scroll exhaust turbochargers in the inside V of the cylinder block • Double air gap insulated exhaust manifold • Indirect charge air cooling • Cylinder management/cylinder on demand (COD) • 2nd generation thermal management system (ITM 2) • Crossflow cooling • MED 17 1.1 engine management system with p-N control • Recuperation system for energy recovery under braking • Start-stop system (model and country dependent, see table on page 7) • Active engine mounting system with oscillating coil actuatorsEngine on the Audi S7 Sportback, viewed from the rear607_0136VersionsThe 4.0l V8 TFSI engine is used on various Audi models. Depending on model series and the markets in which vehicles are available, the engines used have different characteristics. The following table provides an overview of the versions and types or adaptations. You will find further specifications on the following pages.Model lineC71)D42)ModelAudi S6 ’12 Audi S7 Sportback CEUC 309 (420) 550 Asia, USA, Canada, Korea, SAM3)Audi A8 ’12Audi S8 ’12Engine code Power output in kW (HP) Torque in Nm Markets without recuperation system and start-stop system Exhaust emission standardsCEUA 309 (420) 600 Asia, SAM3)CGTA 382 (520) 650 Asia, USA, Canada, Korea• • • • •EU 2 ddk ULEV 2 Tier 2 BR EU 5 EU 5 plus• • • • •EU 2 ddk ULEV 2 Tier 2 BR EU 5 EU 5 plus• ULEV 2 • Tier 2 BR • EU 5 plusEngine weight in kg Gearbox219 DL511-7Q219 AL551-8Q224 AL551-8QThe illustration shows the engine on the Audi S6 ’12. The illustration shows the engine on the Audi S8 ’12. 3) SAM = South American Market.1) 2)!Note The technical descriptions given in this self study programme are based on the engine type of the Audi S6 ’12 and Audi S7 Sportback (C7 series). Differences between this engine and other engine versions are highlighted in the descriptions of the individual modules.7SpecificationsAudi S6 ’12, S7 Sportback (C7 series)The 4.0l V8 TFSI engine is used on the C7 series in a single power rating. Key distinguishing features between the engines in the D4 series are: • One-sided air intake for both turbochargers • No power steering pump • Engine cover designFront view of engine in Audi S7 Sportback with air intake607_0148Torque/power curves4.0l V8 TFSI engine with engine code CEUCPower in kW Torque in NmEngine speed [rpm]607_002Engine code Type Displacement in cm3CEUC Eight cylinder V engine with 90° bank angle 3993 309 (420) at 5000 – 6400 550 at 1400 – 5200 4 1-5-4-8-6-3-7-2 84.5 89 10.1 : 1 Bosch MED 17 1.1 with p-N control Premium unleaded (sulphur-free) 95 RON EU 2 ddk, ULEV 2, Tier 2 BR, EU 5, EU 5 plus 225 S6 ’12, S7 SportbackPower output in kW (hp) at rpm Torque in Nm at rpm Number of valves per cylinder Firing order Bore in mm Stroke in mm Compression ratio Engine management Fuel Exhaust emission standards CO2 emission in g/km Model9Audi A8 ’12, Audi S8 ’12 (D4 series)The 4.0l V8 TFSI engine is used in the D4 series in two power ratings. Key distinguishing features between the engines in the C7 series are: • Double-sided air intake (in the Audi S8 ’12 only) • Additional power steering pump • Engine cover design • The secondary air pump motor has a different installation position (on the right-hand side of the engine compartment)Front view of engine in Audi S8 ’12 with air intake607_00710Torque/power curves4.0l V8 TFSI engine with engine code CEUA 4.0l V8 TFSI engine with engine code CGTAPower in kW Torque in NmPower in kW Torque in NmEngine speed [rpm]Engine speed [rpm]607_003607_004Engine code Type Displacement in cm3CEUA Eight cylinder V engine with 90° bank angle 3993 309 (420) at 5000 – 6000 600 at 1500 – 4500 4 1-5-4-8-6-3-7-2 84.5 89 10.1 : 1 Bosch MED 17 1.1 with p-N control Premium unleaded (sulphur-free) 95 RON EU 2 ddk, ULEV 2, Tier 2 BR, EU 5, EU 5 plus 219 A8 ’12CGTA Eight cylinder V engine with 90° bank angle 3993 382 (520) at 5800 – 6400 650 at 1700 – 5500 4 1-5-4-8-6-3-7-2 84,5 89 9.3 : 1 Bosch MED 17 1.1 with p-N control Premium unleaded (sulphur-free) 98 RON ULEV 2, Tier 2 BR, EU 5 plus 235 S8 ’12Power output in kW (hp) at rpm Torque in Nm at rpm Number of valves per cylinder Firing order Bore in mm Stroke in mm Compression ratio Engine management Fuel Exhaust emission standards CO2 emission in g/km Model11Engine mechanicalsCylinder blockThe crankcase derives from the 4.2l V8 FSI engine of the Audi A8 ’12. It is manufactured by low pressure chill casting from a hypereutectic Alusil alloy. The mechanical and thermal loads are higher than those of the 4.2l V8 FSI engine. To withstand these higher loads, a special heat treatment is used. However, heat treatment varies depending on engine version (there are various degrees of charging). The cylinder liners are mechanically stripped and their surfaces textured by plate honing. Switchable piston cooling jets designed to cool the pistons by means of oil spray are integrated in the cylinder block (see „Switchable piston cooling jets“ on page 38). Cylinder block dimensions Cylinder spacing in mm Bank angle Bore in mm Height in mm Length in mm 90 90° 84.5 228 460Cover module with oil supply connectionsCylinder blockSwitchable piston cooling jetBed plateWindage trayOil pan top sectionOil pan bottom section607_024 12Bed plateThe bed plate is a high pressure die casting made of aluminium alloy. The task of the bed plate is to provide a base for the crankcase and to absorb the loads exerted on the crankcase bearings. It makes a significant contribution to improving overall strength and engine acoustics. Five cast-in-place inserts (crankshaft bearing caps) made of nodular graphite cast iron are used to strengthen the bearing support. In addition, they are bolted to the bed plate at an angle of 45°. Coolant does not flow through the bed plates. However, the bed plate has oil holes and ports for routing the pressure oil. The bed plate is sealed off from the cylinder block using liquid sealant and moulded elastomer seals, -and from the oil pan top section using liquid sealant. The oil filter module is also integrated.Elastomer cylinder block sealsConnection for the oil filter moduleElastomer cylinder block sealCast-in-place insertsThe bed plate is sealed off from the oil pan top section using liquid sealantScrew connection of cast insert at an angle of 45° (on both sides)607_02513Oil module in inside VThere are numerous oil supply ports under the cover in the inside V of the engine block. The cover is bolted directly to the cylinder block, with a metal gasket sandwiched in between.Turbocharger oil feed Turbocharger oil return linePiston cooling jet control valve N522Oil pressure switch, stage 3 F447Crankcase breather Oil return line from fine oil separator of crankcase breather Oil return line from coarse oil separator of crankcase breather Cover of oil module in inside V Turbocharger oil return lineMesh filter in turbocharger oil feed Non-return valve for turbocharger oil supplyOil module in inside VMetal bead gasketOil return line from oil separator of crankcase breatherSealing screwDirection of travelPiston cooling jet switching valve607_026Windage trayThe windage tray closes off the cranktrain from the oil pan. The throws of the crankshaft do not immerse directly into the engine oil. This prevents foaming of the engine oil at high engine speeds. To reduce the weight of the engine, the windage tray is made of plastic.Windage trayReturn line to oil pan14607_027Oil pan top sectionThe oil pan top section is an integral part of the engine-gearbox unit and contributes to the overall strength of the assembly. In non-pressurised spaces, the oil pan top section is sealed off from the bed plate and the oil pan bottom section using liquid sealant. The pressurised spaces have elastomer seals. All oil ducts which transfer contaminated oil from the bed plate and clean oil to the bed plate are an integral part of the oil pan top section. The following components are also integrated in the oil pan top section. • Bypass valve • Oil cooler • Belt tensioner • Additional oil cooler thermostat1) (air-oil) • Coolant pump mounting • Dip stick mountings • Alternator support bracket • Oil return lines from turbochargers and cylinder heads • Oil return shut-off values of the crankcase ventilation system1)In Audi S8 ’12 only.Additional oil cooler thermostat1) (air-oil) Connection to oil filterOil return line shut-off valveMounting for dip stick guide tubeOil return line shut-off valve Oil coolerOil level and temperature sensor G266Oil pan top sectionOil drain screw Oil pan bottom sectionOil pan bottom sectionThe oil pan top section is sealed at the bottom by a bolted-on oil pan bottom section made from sheet aluminium. The oil drain screw as well as the oil level and oil temperature sensor G266 are integrated in the oil pan bottom section.607_02815CranktrainOverview607_020Trapezoidal conrod (cracked)Piston with different main shape, depending on engine versionCrankshaft with different main bearing diameters, depending on engine versionConrodThe conrods of all power output versions are designed as cracked conrods. The upper conrod eye has a trapezoid angle of 13°. The gudgeon pin has a diameter of 22 mm. The conrod bush is made of bronze.PistonCast pistons with a cast-in ring land for the compression ring are used in all engine versions. In the case of the pistons, too, a distinction is made between the 309 kW version and the higheroutput engine versions. The main difference is the shape of the piston crown, as illustrated below. The gudgeon pins have a fine, diamond-like carbon coating with the designation DLC (Diamond Like Carbon).Engine version developing 309 kWEngine versions developing 382 kW or higher607_021 16607_022CrankshaftThe forged steel crankshaft runs on five bearings. Blanks made of different materials are used, depending on engine version. Depending on the engine power rating, however, the finished part is finish-machined differently.Bearings and oil supplyLead-free three-material composite bearings are used as main bearings. Oil is supplied via two through-holes per bearing (crescent-shaped slot in cylinder block). Different bearing materials are used for the conrod bearings. The lower bearing shell is, like the main bearing, designed as a lead-free three-maerial bearing. Lead-free two-material bearings are used as the upper bearing shell. Note: A repair kit with oversize conrod bearings is available as a repair solution (see Electronic Parts Catalogue (ETKA)).Crankshaft dimensions Crank pin diameter in mm Main bearing diameter in mm 90 65 (309 kW) 67 (from 382 kW) Stroke in mm 89Oil intake from the main oil galleryCrescent-shaped slot for supplying the main bearings with two throughholes in the upper bearing shellOil supply duct for the conrod bearings607_010Vibration damperHousingBearing elements Flywheel ringSilicone oilCoverFunction The visco damper reduces rotary vibration produced by gas and mass forces in the internal combustion engine (intra-engine combustion, rotating and oscillating masses). The vibrations result in relative movement between the housing and flywheel ring. As a result, the silicone oil is subjected to shear load. These stresses act on the entire surface of the gap between the flywheel ring and the housing. The overall load is the resultant damping effect.17Crankcase ventilationThe crankcase is ventilated via both cylinder heads. The blow-by gases are channelled into the crankcase ventilation module through separate ports, which are routed to the intake manifolds and then to the charge air ducting module. The crankcase ventilation module is located in the inside V of the engine and performs several tasks: • Coarse oil separation • Fine oil separation • Pressure control via the pressure control valve • Positive crankcase ventilation (PCV)OverviewCharge air cooling module Positive crankcase ventilation moduleIntake of blow-by gases into the intake manifold (at full throttle)Flow of blow-by gases inside the air manifold housingIntake of blow-by gases into the intake manifold607_058Oil return duct from the fine oil separatorOil return line shut-off valve for the coarse oil separatorOil return duct from the coarse oil separator!18Note A leaky oil return line from the coarse oil separator can result in increased engine oil consumption or blue smoke in the exhaust. The oil return line shut-off valves are integrated in the oil pan upper section. They cannot be replaced separately.Coarse oil separationIn the first, high-volume chamber, the blow-by gas flow changes direction by approx. 180°. The larger oil droplets bounce off the walls because they have more inertia and flow into the collecting chamber at the bottom of the coarse oil separator. Here, there is a drainage outlet which is connected to the cover of the oil module in the inside V. The outgoing oil flows back into the oil pan through an oil return duct below the oil level in the cylinder block. An oil return shut-off valve closes automatically when the engine is running, due to pressure differential in the crankcase and oil mist separator. This prevents untreated blow-by gases from bypassing the fine oil mist separator.Cover of oil module in inside VCoarse oil separatorLarger oil droplets are separated by changing the direction of the blow-by gas flow Oil return line shut-off valve for the fine oil separator Oil return duct from the coarse oil separator into the oil pan607_059Oil return line shut-off valvesTwo oil return line shut-off valves are built into the oil return ducts. They prevent the intake of untreated blow-by gases from the crankcase. The valves in question are spring-loaded ball valves. They are clipped into the top section of the oil pan.Oil return from the coarse or fine oil separatorOil return into the oil pan607_120 19Fine oil separationThe blow-by gas flows out of the coarse oil separator, through the fine oil separator and into the second chamber. The impactor, the pressure control valve, the blow-by valves and the PCV valve are all located here. Initially, the blow-by gas is treated in the fine oil separator. This works on the same principle as an impactor. It also uses a pressure limiting valve, which opens at high blow-by volumetric flow rates and thus limits pressure loss throughout the entire system. Like the coarse oil, the separated fine oil is returned to the oil pan through a separate connection in the inside V of the engine block. A non-return valve is also fitted here. A treated blow-by gas flows through the single-stage pressure control valve. Depending on the pressure conditions in the air supply system, the blow-by gas is admitted to the combustion chamber through the blow-by valves integrated in the air charging module or positive crankcase ventilation module.OverviewIntake of blow-by gasesImpactor with flutter valveFine oil separation via an impactor with flutter valveCoarse oil separatorPressure control valveCover oil oil module in inside VAdmission of separated oil into the oil module in the inside VOil return duct into the oil pan607_060Reference For more information on the design and functional principle of an impactor, please refer to Self Study Programme 490 "Audi 6.3l W12 FSI engine".20Inflow of treated blow-by gasesIdle and partial-throttle operation Vacuum is present in the air supply at idle and at partial load. The treated blow-by gases are admitted into the charge air cooling module. In the process, the blow-by valve for idle and partial load is opened by the suction effect.Charge air cooling Charge air cooling Admission of blow-by gases at idle and at partial loadBlow-by valve (open)Pressure control valve Positive crankcase ventilation moduleBlow-by valve (closed)Treated blow-by gases from the coarse and fine oil separators607_061Full throttle operation If vacuum is present in the charge air line when the engine is in charging mode, the blow-by valve in the charge air module which is operating at partial load closes. The treated blow-by gas is now admitted upstream of the turbocharger by the blow-by valve integrated in the positive crankcase ventilation module.Intake air from air filterConnecting socket for intake of blow-by gasesIntake air to the turbochargers607_062 21Positive crankcase ventilation (PCV)Fresh air is admitted into the crankcase via the positive crankcase ventilation module. The crankcase is ventilated at idle and at partial load only. The fresh air flows into the positive crankcase ventilation module through the "full throttle" blow-by connection. A defined amount of fresh air is admitted into the crankcase via a connection on the cover of the inside V via a plate valve and a bore in the positive crankcase ventilation module. If the engine is in charging mode, the plate valve closes due to pressure differences.Air routingIntake air from air filterBlow-by connection "full throttle"Intake air to the turbochargersConnecting socket for intake of blow-by gasesPlate valve 2Blow-by valve (closed)Positive crankcase ventilation moduleVentilation hole in cylinder blockPCV settling chamber in the oil module in the inside V607_06322Activated charcoal filter (ACF) systemThe ACF system has been adapted to the new system conditions. This applies in particular to the admission of fuel vapours for combustion. In previous systems with charged petrol engines, fuel vapours were admitted at two points. Firstly, fuel vapours were admitted downstream of the throttle valve at idle and at low partial load due to the vacuum present in the air intake. Secondly, fuel vapours were admitted upstream of the turbine during the phase in which charge pressure is present in the system. Fuel vapour admission was controlled by a mechanical valve system. The engine management system of the 4.0l V8 TFSI engine is configured such that the air supply is largely unrestricted at full throttle. As a result of this, the pressure differential is too small to flush the ACF canister. For this reason, the ACF system is designed in such a way that the fuel vapours are admitted at idle and at low partial load only. For this purpose, the activated charcoal canister solenoid valve N80 is activated on the basis of a characteristic map.Admission of fuel vapours into the charge air cooling module Non-return valve Activated charcoal canister on fuel tank Intake manifold valve vacuum cellIntake manifold valve vacuum cellIntake manifold valve valve N316Activated charcoal canister solenoid valve 1 N80607_121Activation of the intake manifold valvesThe intake manifold valves are integrated in the intake manifolds (see Fig.607_051 on page 56). When actuated, they shut off the lower air duct in the cylinder head. The induces a tumbling type of movement in the air flowing into the combustion chambers. The ports in the cylinder head are separated by dividers. All intake manifold valves in a cylinder bank are mounted on a common shaft. The shaft is driven by a spring-loaded vacuum cell. Both intake manifold valve vacuum cells are commonly actuated by the intake manifold valve valve N316. N316 is positioned in the area of cylinder 4 on the intake manifold adjacent to the intake manifold valve potentiometer G336 (see Fig. 607_121). A vacuum line is routed around the engine in order to supply the vacuum cell on cylinder bank 2 with vacuum from N316. The engine control unit receives feedback on the position of the intake flaps from intake manifold potentiometers G336 and G512. Both potentiometers are positioned opposite the vacuum cell. This allows the shafts to be tested for proper functioning.23Cylinder headsThe cylinder heads of the 4.0l V8 TFSI engine have been redesigned. The challenge facing the engineers was to meet the higher mechanical and thermal demands compared to the cylinder heads of the 4.0l V8 FSI engines. The cylinder heads of all power output versions of the engine are identical in terms of their design. The only distinction is that the engine versions with power outputs of higher than 309 kW have different camshaft timings (camshaft event durations). The key difference is the reverse layout of the intake and exhaust ends (Hot Side Inside – HSI). This layout makes for compact design, improved thermodynamics and short gas flow paths with a minimum of flow losses. The 4.0l V8 TFSI engine responds crisply to accelerator pedal inputs. A sophisticated system of insulating hot components, particularly the manifold, ensures that thermal conditions in the inside V are stable. The fresh air intake system is located on the outside of the cylinder banks. Switchable flaps in the intake ducts induce a tumbling type of movement in the incoming air. This swirling fuel-air mixture cools the combustion chambers, allowing a high compression ratio to be achieved during charging without causing combustion knock.Technical features• • • • • • • • • • Aluminium cylinder head with twin composite camshafts Four valves per cylinder Cylinder head covers with ladder frame Variable intake and exhaust valve timing Pulse sender (Hall sensors) for camshaft position monitoring Crossflow cooling Cooled intake and exhaust valve bridge cylinder on demand via AVS, see page 60 Three-layer cylinder head gasket The cylinder head gaskets are sealed with liquid sealant • Intake ports with divider • Central layout of the spark plugs (in the centre of the valve stem) • Lateral layout of the injectors • The high-pressure fuel pumps are driven by the exhaust camshafts (triple lobe cam) • The mechanical vacuum pump is driven by the intake camshaft of cylinder bank 1 • Non-return valves prevent engine oil from flowing back (evacuation of the pressure ports) • Oil mesh filter for protection against contaminationValve gearThe valves are actuated by roller cam followers. They have a different geometry to allow for cylinder on demand. The roller cam followers with wide rollers are assigned to the cylinders without cylinder on demand. The roller cam followers with narrow rollers are assigned to the cylinders with cylinder on demand. Other features: • Static hydraulic valve lash adjustment • Sodium-filled exhaust valves with reinforced seats for cooling • Solid-stem intake valves with reinforced seats • Sintered lead steel exhaust valve guides • Brass intake valve guides • Simple valve springs with relatively low tension • Valve lift: 11 mmVariable valve timingThe intake and exhaust valve timings are continuously variable. Each of the valves has an adjustment range of 42° crank angle. The position of the camshaft is monitored by a Hall sender. After shutting off the engine (the oil pressure drops), the camshaft adjusters are locked by a spring-loaded locking pin. The variable valve timing (VVT) allows the internal recirculation of exhaust gases by means of valve overlap. Exhaust gases are recirculated both in 8 cylinder mode and in 4 cylinder mode.Legend of figure on page 25:1 2 3 4 5 6 7 8 9 10 11 VVT actuators Hall sender G40 High-pressure fuel pump Intake camshaft timing adjustment valve N205 Exhaust camshaft timing adjustment valve 1 N318 Hall sender 2 G163 Cylinder head cover Intake camshaft Movable cam member Roller cam follower with support element Valve spring retainer 12 13 14 15 16 17 18 19 20 21 22 23 Valve stem seal Valve cotters Valve spring Intake manifold Non-return valve with vacuum pump connection Intake manifold valve potentiometer G336 Port dividers in cylinder head Fuel rail Fuel injectors Exhaust camshaft Exhaust valve Cylinder head 124Design41 5 26 3798 1011 12 13 14 1615 2122 17181920Direction of travel23607_029 25Chain driveThe engine is controlled by a chain drive with four chains in a biplanar configuration. The chain drive is located on the power output side of the engine. Hydraulic tensioners with a non-return valve are used as a tensioning system. All chain drives use roller chains. Chain drive A distributes power from the crankshaft to the idler gears. Chain drives B and C act as a cylinder head drive train transferring power from the idlers to each of the camshafts. Chain drive D acts as a spur gear drive. The valve timing is set and checked using the new locking tool T40264/1-3. The cylinder head covers do not have to be removed in order to lock the camshafts.Cylinder bank 2Chain drive ACylinder bank 1Chain drive BChain drive C607_008Spur gear driveChain drive DAuxiliary drive gear moduleChain drive D drives a gear module, which in turn drives nearly all auxiliary units (see „Other auxiliary units“ on page 27). The alternator is the only exception („Alternator“ on page 27).!26Note The chain gears of the camshaft adjusters are designed as trioval chain gears. The special instructions given in the ELSA system must be observed during installation work.Auxiliary units driveAlternatorThe alternator is driven by a five-rib poly-V belt. An automatic belt tensioner with a damping function provides the correct amount of pre-tensioning.Alternator Belt tensioner Vibration damperOther auxiliary unitsThe other auxiliary units are driven by the crankshaft through chain drive D, a spur gear drive, a gear module and splines.607_009A/C compressorCoolant pumpOil pumpChain drive D Thermostat for mapped engine cooling F265Power steering pumpGear module607_011Power steering pumpThe power steering pump on the Audi A8 ’12 is driven by the engine. The power steering pump is driven by the crankshaft through chain drive D, a spur gear drive and a gear module. C7 series vehicles no longer have a power steering pump drive. An electro-mechanical steering system is used here (see SSP 480).27Oil supplyOverviewThe 4.0l V8 TFSI engine has a wet sump lubrication system. For the first time, activatable piston cooling jets are used in an 8-cylinder petrol engine.Cylinder bank 1Oil ports for supplying the camshafts and the support elements on the roller cam followersOil module in inside VMain oil galleryOil filterRiser line to main oil galleryEngine oil cooler supply from cooling circuitEngine oil cooler return to cooling circuit28Cylinder bank 2Turbocharger oil supplyChain tensionerCamshaft adjusterSwitchable piston cooling jetsOil pump with intake from oil pan607_03529Oil pumpThe 4.0l V8 TFSI engine has a regulable oil pump, which is designed in such a way that it can operate in two pressure stages. In addition, engine oil demand is continuously adapted by regulating the volumetric flow of the pump (in both pressure stages). Use of this pump has improved fuel economy. For this purpose, the pump is operated in the lower pressure stage at low engine speeds (low drive output). The low pressure level is at a relative pressure of approx. 2 bar. The high pressure level is at approx. 4.5 bar. The pressure relief valve in the pump opens at approx. 11 bar (cold start valve). The oil pump is bolted to the bed plate. It is driven by the spur gear drive (chain drive D) via a spline. The spur gear drive of the oil pump also drives the engine coolant pump (see fig. on page 26).Drive spline607_032DesignIn design terms, the pump is a vane cell pump with an excentrically mounted adjusting ring which is an integral part of the pump interior. Rotating the adjusting ring changes the volume of the pump interior and hence the delivery rate or, after change-over, the pressure inside the system. A specially shaped intake manifold with mesh filter and rubber base ensures that engine oil is taken in safely from the oil pan and in a manner favourable to flow in the pump, even under high transverse vehicle acceleration.Oil pump coverOil pump in oil pan top sectionControl springs607_031Ball valve Adjustment ringVane cellsDrive shaftAdjustment device The adjustment ring rotates when oil pressure acts on the control faces, whereby the inflow to control face 2 can be controlled by the oil pressure control valve. The counterforce is generated by two control springs. They push against control face 2 of the adjusting ring. The springs have special characteristic curves. This ensures that the flow rate is always correct in both the low and high pressure stages.Oil pump housingIntake manifold with mesh filter30Volumetric flow control function (identical for both pressure stages)Increased delivery rate At rising engine speed, a pressure drop occurs within the system due to the increased oil requirements of systems. As a result, the control springs displace the adjusting ring in such a way as to enlarge the space inside the pump, thereby increasing the delivery rate of the pump. Reduced delivery rate At decreasing engine speed, the engine requires less oil and the pressure increases. The higher pressure acts on the control face(s) of the adjusting ring and displaces the ring in such a way that the space inside the pump decreases, thereby reducing the delivery rate of the pump.Control face 1Adjustment ringDelivery chamberSupport bracket607_033607_034Vane cellsControl springsControl face 2Schematic diagram of the oil pressure control systemE Dto systemsF G Volumetric flow control (control face 1) C A Pressure control (control face 2) B N428607_030Key: A B C D1)Oil screen Control valve Oil pump Water-oil coolerE F G N428Oil filter Thermostat1) Air-oil heat exchanger1) Oil pressure control valveOnly in engine versions with power outputs of higher than 309 kW.31Oil pressure regulation functionLow pressure level The oil pressure regulation valve N428 is actuated by the engine control unit, thereby opening the port to control face 2. The oil pressure generated by the pump now acts on both control faces and increases the rotation of the adjusting ring. The pump space decreases in size, with the result that less oil is conveyed. The oil pressure drops. The oil pump runs at a lower drive output, providing better fuel efficiency.Oil pressure control valve N428 activatedControl face 2607_040High pressure level The high pressure stage is selected at an engine speed of 4000 rpm. The oil pressure regulation valve N428 is deactivated for this purpose. The oil flow to control face 2 of the adjusting ring is interrupted as a result. The control springs now push back the adjusting ring, thereby decreasing the space inside the pump. The delivery rate of the pump increases and the oil pressure is adjusted to the high pressure level. The oil pushed back by control face 2 is diverted into the oil pan via N428 (see Fig. 607_030 on page 31). The lower pressure level is selected when the engine speed drops below 3500 rpm.Oil pressure control valve N428 deactivatedControl springsAdjusting ring is set to maximum delivery607_04132Oil coolingThe oil conveyed by the oil pump is initially admitted to an oil ducting system in the top section of the oil pan. To this end, it must pass a non-return valve. This ensures that the oil circuit does not run dry. The oil then flows through the oil cooler, which is designed as a water-oil cooler and thus is integrated in the engine cooling circuit (see „Cooling system“ on page 44). The water-oil cooler is bolted to the top section of the oil pan below the vibration damper. The oil from the oil cooler flows back into the oil ports of the oil pan top section, and from there to the bed plate. An additional bypass valve is fitted in order to protect the oil cooler. It opens at a pressure of 2.5 bar (relative) and diverts oil into the oil cooler return line.OverviewBypass valve Additional oil cooler (air-oil) Oil pump Non-return valve Coolant return line Oil cooler feed lineOil cooler (coolant-oil)Oil cooler return lineCoolant feedAdditional air cooler thermostat607_042Additional oil coolerAn additional oil cooler is available for the engine version in the Audi S8 ’12. It is an air-oil cooler and is cooled by the airstream at the front end of the vehicle. Unlike the oil cooler, oil does not continuously flow through this cooler. Oil flow through the additional oil cooler is enabled by a thermostat (see „Schematic diagram of the oil pressure control system“ on page 31). The thermostat is located in the oil port of the oil pan top section and opens at an oil temperature of 110 °C. The additional oil cooler vents itself automatically. The additional oil cooler does not run dry when changing the engine oil.!Note The additional oil cooler thermostat cannot be replaced separately. The oil pan top section must be replaced, if necessary.33Oil filterThe oil coming from the oil pan top section (oil cooler) flows into the cylinder block, where the mounting for the oil filter is located. The oil filter consists of a polymer filter cartridge and is supported by a plastic cap. The plastic cap is bolted to the bed plate when replacing the filter. The filter is mounted in suspension in an easy-to-service position in the engine. To simplify oil filter replacement, there is a drain screw on the plastic cap.607_043Oil pressure switches F22 and F378Above the oil filter there are two oil pressure switches which monitor both pressure stages (see „Oil pressure monitoring“ on page 36). A third oil pressure switch is used for monitoring the oil pressure for the piston cooling jets (see „Oil pressure switch, stage 3 F447“ on page 42).Oil pressure switch F22Oil pressure switch for reduced oil pressure F378607_04434Oil consumersThe treated oil flows from the oil filter into the main oil gallery. From here, all oil consumers are supplied with engine oil:Main oil gallery• • • • • • •Crankshaft Piston cooling jets (switchable) Chain drive (chain tensioner) Cylinder heads (valvegear, variable valve timing) Oil pump (oil pressure regulation) Exhaust turbocharger Vacuum pumpOil filter607_045Additional oil temperature measurementThe oil temperature is measured en route to the main oil gallery. For this purpose, oil temperature sensor 2 G664 (NTC) is bolted into the riser line. If the engine oil temperature exceeds 125 °C, engine power output is reduced by the engine control unit. This serves to protect the lead-free bearing shells in the cranktrain (see „Cranktrain“ on page 16). Engine power output is also reduced if the engine control unit receives an implausible signal or no signal from the sensor. A diagnostic trouble code is stored in the engine control unit. A fault indicator lamp is not activated.Riser line to main oil gallery Oil temperature sender 2 G664607_04635Oil pressure monitoringBasically, the oil pressure is monitored by two oil pressure switches. This is necessary, because two oil pressures are produced.Signal flowDisplay and operation CAN busPowertrain CAN bus607_038Key: 1 2 3 4 5 Warning bit ("red oil can") 2 text bits Change-over bit = 1 Signal from oil pressure switch F22 Signal from oil pressure switch fo rreduced oil pressure F378 F22 F378 J285 J533 J623 Oil pressure switch Oil pressure switch for reduced oil pressure Control unit in instrument cluster Data bus diagnostic interface Engine control unitFunction and signals of the oil pressure switchesThe two oil pressure switches are used for monitoring the oil pressure. The oil pressure switch for reduced oil pressure F378 checks for the presence of oil pressure. Oil pressure switch F22 monitors the high pressure level of the regulated oil pump if the latter is operating in the high pressure stage.Signals from the oil pressure switches The oil pressure switch is evaluated in the engine control unit J623 (in previous concepts involving the use of a single-stage oil pump, the oil pressure switch was read in and evaluated by the control unit in the instrument cluster J285). The oil pressure switches are NO contacts which connect to ground as soon as the required oil pressure is present. Both oil pressure switches are connected directly to the engine control unit J623.36Oil pressure monitoring process The oil pressure switches are monitored in the engine control unit at engine ON and checked for plausibility at engine OFF.Plausibility check at engine OFF When the engine is turned OFF, no signal from a connected oil pressure switch may be present. Otherwise, an electrical fault must be assumed. At terminal 15 ON, a warning is displayed in the instrument cluster ("red oil can" together with fault text "Switch off engine and check coolant level").Switch off engine and check coolant levelD8607_039Warning at engine ON Depending on the oil temperature, the oil pressure switches are monitored upwards of a defined engine speed threshold. Oil pressure switch F22 (high pressure stage): The oil pressure switch F22 is monitored as soon as the regulated oil pump is operating in the high pressure stage and the engine speed exceeds a value computed in the characteristic map (this is dependent on the oil temperature). If it is determined that the switch is not closed, the engine electronics warning lamp K149 is activated. In addition, the engine speed is limited. The limited engine speed is indicated by a text message in the instrument cluster and by a yellow speed symbol.Oil pressure switch F378 (low pressure stage): The oil pressure switch is generally monitored when the engine is cold (up to 60 °C), i.e. at idle. When the engine is at operating temperature, the oil pressure switch is not monitored until high engine speeds are reached. If the switch is not closed, the "red oil can" warning is displayed in the instrument cluster together with the fault text "Switch off engine and check coolant level".Fault analysis options Diagnostics can be carried out in the engine control unit using the oil pressure monitoring function.37Switchable piston cooling jetsIn principle, it is not necessary to cool the piston crowns with oil spray in every engine operating situation. If the piston cooling jets are deactivated, the oil pump has less oil to convey (volumetric flow control), which, in turn, saves a small amount of fuel. The piston cooling jets are activated and deactivated by the piston cooling jet control valve N522. This valve is located in the inside V of the cylinder block. A switching valve which controls the oil flow to the piston cooling jets is actuated hydraulically by N522.Overview of system componentsCover of oil module in inside VPiston cooling jet control valve N522Oil pressure switch, stage 3 F447Main oil gallerySwitching valve, self-opening (spring force)Oil intake from the oil pumpSwitchable piston cooling jetCentral oil distributor rail for all piston cooling jets607_04738FunctionPiston cooling jets activated If the piston cooling jet control valve N522 is not activated by the engine control unit, the port to the piston cooling jets is open. The piston crowns are sprayed with oil spray. This ensures that the piston crowns are cooled in the event of the following faults: • Faulty cable, loose connector, sticking electrical control valve • Sticking hydraulic switching valve • Faulty activationPiston cooling jet control valve N522 − not activatedUnpressurised System pressureMain oil galleryOil intake from the oil pumpOil pressure switch, stage 3 F447 Switching valve, self-opening (spring force) − opens at approx. 0.9 barPiston cooling jets spray the oil onto the piston crowns607_01539Piston cooling jets deactivated The deactivation of the piston cooling jets is controlled. A characteristic map is stored in the engine control unit for this purpose (see figure on page 43). The piston cooling jets can only be switched off when current is present. Port A is opened when the piston cooling jet control valve N522 is activated. Oil flows from the main oil gallery onto the control piston of the switching valve. Since oil pressure is now present from both sides of the piston, the force of the spring in the switching valve is predominant and closes the inlet to the piston cooling jets.Piston cooling jet control valve N522 − activatedUnpressurised System pressureMain oil galleryAOil intake from the oil pumpOil pressure switch, stage 3 F447 – not switched Switching valve, closed (spring force)Piston cooling jets do not spray any oil onto the piston crowns607_01640Ventilation function The inflow to the second piston face of the switching valve is interrupted by the deactivation of the piston cooling jet control valve N522. At the same time, a port in the piston cooling jet control valve N522 opens. This allows the oil to drain off the second piston face of the switching valve in an unpressurised state. The diverted oil flows into the oil return port of the exhaust turbocharger.Piston cooling jet control valve N522 − not activatedUnpressurised System pressureMain oil galleryThe switching valve is ventilated into the unpressurised oil space via the control valve N522Oil intake from the oil pumpOil pressure switch, stage 3 F447 – switched Switching valve, open (spring force)Piston cooling jets spray oil onto the piston crowns607_01741Oil pressure switch, stage 3 F447This oil pressure switch is bolted to the cover in the inside V. It measures the oil pressure between the switching valve and the piston cooling jets. If the piston cooling jets are activated, the oil pressure switch, stage 3 F447 is closed. Its switching range is between 0.3 and 0.6 bar. If the piston cooling jet control valve N522 is not activated by the engine control unit, then the port to the piston cooling jets is open (F447 closed). This ensures that the piston crowns are cooled in the event of a fault in the activation circuit or in the wiring.Oil pressure switch, stage 3 F447 Cover in inside VA sticking piston cooling jet control valve N522 in the "piston cooling jet OFF position" can be detected using the diagnostics. Engine power output is reduced, because no piston cooling is provided in this case.Piston cooling jet control valve N522The piston cooling jet control valve N522 is located in the cover of the oil module in the inside V of the cylinder block. It is supplied with oil pressure through a connection to the main oil gallery.Oil pressure from the main oil galleryOil flow from energised control valve to switching valve, piston cooling jets OFFOil flow from the switching valve via the deenergised control valve into the turbocharger oil return chamber (switching valve ventilation) Piston cooling jets ON607_04942Functional ranges of the piston cooling jetsThe operating point and the "on" time of the piston cooling jets are defined by a characteristic map. In this case, engine torque and engine speed are used as calculation variables. The area indicated red in the diagram shows when the piston cooling jets are deactivated. The piston cooling jets are activated when the engine speed exceeds 2500 rpm and when a preset torque is exceeded in dependence on engine speed.Operating pointsEngine torque [Nm]Piston cooling jets activated, i.e. pistons are cooled with oil sprayPiston cooling jets deactivated, i.e. no piston coolingEngine speed [rpm]607_04843Cooling systemSystem overviewDepending on engine and vehicle version, different cooling systems are used, e.g. with different radiator configurations.Coolant circulation pump 2 V178 (ATL assistance run-on)Water-cooled exhaust turbochargerWater-cooled alternatorOil cooler (coolant-oil) Switching valve for static coolant Mechanical coolant pumpThermostat for mapped engine cooling F265607_091Legend of figure on page 45: F265 G62 G83 G694 N279 N489 N509 V7 V50 V51 V55 V177 V178 V18844Thermostat for mapped engine cooling F265 Coolant temperature sensor Coolant temperature sensor at radiator outlet Temperature sensor for engine temperature control Heater coolant shut-off valve Cylinder head coolant valve Gear oil cooling valve Radiator fan Coolant circulation pump Coolant run-on pump Circulation pump Radiator fan 2 Coolant circulation pump 2 Charge air cooling pump1 2 3 4 5 6 7 8 9 10 11 12 13Heater heat exchanger Vent screw ATF heat exchanger Alternator 2x exhaust turbocharger Coolant expansion tank Engine oil cooler Coolant pump Charge air cooler Radiator Auxiliary radiator Radiator for charge air cooling Auxiliary heaterAudi S6 ’12, S7 Sportback (C7 series) with and without auxiliary heaterN279 Cooled coolant Hot coolant ATF1 2V5513607_0691 2 V503 N509V178V515G624 N489 6 G6948F2657G839V7V1771011V188 12607_065 45Audi A8 ’12, Audi S8 ’12 (D4 series) without auxiliary heater The cooling systems of both vehicle types are identical apart from one exception. This applies to the cooling and heating of the ATF (see „Gear oil cooling/heating“ on page 50). The version here shows the cooling system of the Audi A8 ’12.123 4 V50V178V515G626 N489 N509 G694 N48889F2657 G83 10V7V17712 111314V18815607_06646Audi A8 ’12, S8 ’12 (D4 series) with auxiliary heater12N279 3V55 V50 16607_070Cooled coolant Hot coolant ATFKey: F265 G62 G83 G694 N279 N488 N489 N509 V7 V50 V51 V55 V177 V178 V188 Thermostat for mapped engine cooling F265 Coolant temperature sensor Coolant temperature sensor at radiator outlet Temperature sensor for engine temperature control Heater coolant shut-off valve Gearbox coolant valve (A8 ’12 only) Cylinder head coolant valve Gear oil cooling valve Radiator fan Coolant circulation pump Coolant run-on pump Circulation pump Radiator fan 2 Coolant circulation pump 2 Charge air cooling pump 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Front heater heat exchanger Rear heater heat exchanger Vent screw ATF heat exchanger 2x exhaust turbocharger Alternator Engine oil cooler Coolant expansion tank Coolant pump Charge air cooler Auxiliary radiator (A8 ’12 only) Radiator Auxiliary radiator 2 Auxiliary radiator (hot-climate countries and S8 ’12 only) Radiator for charge air cooling Auxiliary heater47Engine circuit and cooling moduleMechanical coolant pumpThe engine circuit is driven by the main coolant pump. It provides the required volumetric flow for: • cooling the engine and the exhaust turbocharger • circulation through the engine oil cooler The coolant pump is designed as a mechanically driven coolant pump on the basis of the pump used in the 4.2l V8 FSI engine. The pump is located at the front left bottom section of the engine, as viewed in the direction of travel. The pump is driven via an input shaft by the engine, which is coupled to the crankshaft via a rigid oil pump reduction gear. The pump rotates clockwise, as viewed in the direction of travel. The thermostat required for controlling the coolant temperature is flange-mounted to the coolant pump on the intake side.Switching valve for static coolant (ITM)The Innovative Thermal Management system utilises a ball valve. When the valve is closed, it shuts off the coolant flow. The coolant remains static throughout the engine, the oil heats up to operating temperature quickly and the phase of increased friction losses is shortened. The coolant flow stops whenever the engine is started at coolant temperature of below 80 °C. The switching valve is flange-mounted between the vibration damper and the air intake on the cylinder block. It is integrated in the coolant tube on the pressure side between the coolant pump and cylinder block. The valve is actuated pneumatically by a vacuum cell. The vacuum is provided by the vacuum pump and controlled by an electrical change-over valve (cylinder head coolant valve N489). The switching valve, vacuum cell and electrical change-over valve form an assembly unit. All switching operations are defined by a characteristic map. The ball valve is activated for the "closed" switch position. No intermediate positions are implemented. When the engine is at operating temperature, the coolant flow is phased in again. This avoids a sudden drop in coolant temperature in the cylinder-engine block due to sudden inflow of coolant. The switching valve can be activated by the actuator diagnostics for diagnostic purposes. Testing can also be done manually or using a manually operated vacuum pump.Switching valve closedSwitching valve openVacuum cell Ball valveCylinder head coolant valve N489from the mechanical coolant pump to the engine607_084 48 607_085Thermostat for mapped engine cooling F265The thermostat is positioned on the intake side of the coolant pump and is opened in a temperature-controlled manner by a wax filled element. The opening temperature can also be reduced using a heating element. The thermostat is activated by the engine management system, in which a characteristic map is stored. The control unit utilises the input variables of air temperature, engine load, speed and coolant temperature for calculation purposes. It calculates from these variables the continuously variable electrical heating of the expanding element. The thermostat mechanism is identical to that of a sleeve valve thermostat. It is identical in design and functional principle to that of the 6.3l FSI W12 engine which is described in Self Study Programme 490.Switching valve for static coolantOperating temperatures Operating range Thermostat opens at (deenergised) Thermostat opens at (energised)1)- 40 to + 135 °C 97 ° ± 2 °C1)Dependent on current feed and ambient temperature (map)607_080Mechanical coolant pump Thermostat for mapped engine cooling F265Thermostat closed (bypass open)From the bypass From the exhaust turbochargers, gearbox cooling system and equalising tankThermostat open (bypass closed)To the coolant pump From the exhaust turbochargers, gearbox cooling system and equalising tank From the main radiator607_082607_081Bypass thermostat plate (small plate)Thermostat valve (ring sleeve)Reference For further information about the electronic coolant control system, please refer to Self Study Programmes 222 "Electronically controlled cooling system" and 267 "The 6.0 l W12 engine in the Audi A8 - Part 1".49Gear oil cooling/heatingAnother function of the Innovative Thermal Management (ITM) system is that of cooling and heating the gear oil (ATF). Depending on vehicle type and engine version, there are differences in the system. This is why there are two versions of this cooling subsystem: • System 1: Audi S6 ’12, S7 Sportback, S8 ’12 • System 2: Audi A8 ’12 (engine version developing 309 kW)System 1 in the Audi S6 ’12, S7 Sportback and S8 ’12Only a gearbox cooling system is used. A solenoid valve (gearbox cooling valve N509) and a pump (coolant run-on pump V51) are built into the ATF cooling circuit for this purpose. The gearbox cooling valve N509 and the coolant run-on pump V51 are activated by the engine control unit J623. The coolant run-on pump V51 is activated by the engine control unit when the gear oil temperature exceeds 96 °C. The gearbox cooling valve N509 opens at  92 °C and closes again at  80 °C.Coolant run-on pump V51607_071Key: 1 N488 N509 V51 V178 ATF heat exchanger Gearbox coolant valve Gearbox oil cooling valve Coolant run-on pump Coolant circulation pump 21N509V178V51The illustration shows the Audi A8 ’12.Cooled coolant Hot coolant ATF607_06850System 2 in Audi A8 ’12 (engine version developing 309 kW)The Audi A8 ’12 developing 309 kW has a "gear oil cooling" function and a "gear oil heating" function. For this purpose, a second solenoid valve is integrated in the tubing (gearbox coolant valve N488). It is integrated in the coolant flow between the auxiliary water cooler and the gear oil cooler. N488 is activated by the gearbox control unit. N488 and the AFT cooling circuit are open when deenergised (ignition OFF).Function If the engine is cold and the ignition is turned on, N488 is activated, and thus closed, by the gearbox control unit. The gear oil cooling valve N509, which is activated by the engine control unit, also remains closed. Rapid engine warm-up is achieved by means of "static" coolant. If the engine has reached its operating temperature, the command "heat gear oil" is received from the "theromanager software" in the engine control unit. N509 is activated by the gearbox control unit. Hot coolant from the engine now flows through the gearbox ATF cooler and heats the gear oil. Pumps V51 and V178 (see page 52) do not run. If the optimal temperature for the gearbox of 85 °C is reached, N509 is closed again (both valves are shut). N488 is opened when the gear oil temperature