217 217 Service. The V8-5V Engine Construction Features and Functions Self-Study Programme 217 All rights reserved. Subject to technical modifications. AUDI AG Abteilung I/VK-5 D-85045 Ingolstadt Fax 0841/89-36367 940.2810.36.
AUDI has been producing advanced 8-cylinder engines since 1988. Their capacity has increased from 3.6 l to 4.2 l. The V8 engine in combination with Aluminium Space Frame technology was the technical basis for Audi's breakthrough into the luxury class. SSP217_048 Steps to enhance the value of the Audi A8 have included the redesign of the V8 engine. The new V8-5V engines are now also available for the Audi A6 model range.
Content Page Introduction Technical data ....................................................................... 5 Engine - Mechanics Crankgear .............................................................................. Engine mounting .................................................................. Engine lubrication ................................................................ Cooling circuit .......................................................................
Introduction V8-5V Engines SSP213_073 Major modifications were made to the V8 engines during the course of further development. Emphasis was placed on the following development objectives: – compliance with future exhaust-emission regulations – reduction of fuel consumption – increase in torque and power – improvement of comfort and convenience – reduction of engine weight – increased use of shared components for the AUDI engine series.
Technical data AQG AQF (A8) ARS (A6) 4172 cm3 Power output 191 kW 260 hp at 6000 rpm 228/220 kW 310/300 hp at 6000 rpm 51.6 kW/l 70.3 hp/l 54.6 kW/l 74.3 hp/l 350 Nm at 3200 rpm 410 Nm at 3000 rpm Specif. torque 94.7 Nm/l 98.3 Nm/l Bore 84.5 mm Compression ratio Weight Engine management Fuel 350 175 300 150 250 125 200 100 150 75 100 50 50 25 0 0 Speed (rpm) 500 250 450 225 400 200 350 175 300 150 250 125 200 100 150 75 100 50 50 25 84.5 mm 82.4 mm 93.
Engine - Mechanics Crankgear SSP217_054 The crankcase has been adapted to the modifications made to the oil supply system and cooling circuit. Cracked-steel conrods have been used for the 3.7 l engine since 1995 and are now also being used for the 4.2 l engine. The conrods are shared components used in both the 2.4 l and 2.8 l engine.
SSP217_055 Owing to the design of the valve recesses, the pistons are specifically intended for use in the appropriate cylinder bank only.
Engine - Mechanics Wide, milled ventilation recesses above the thrust bearings reduce pumping losses. Bolts are also inserted at the side of the two front crankshaft bearing caps to improve running smoothness (see SSP 198, page 6). SSP217_007 The locking mandrel (V.A.G 3242) used for the V6 engines is also used for locking the crankshaft.
Marking The central bolt does not have to be unscrewed for the vibration damper to be removed. The marking indicates the ignition TDC of the 5th cylinder. SSP217_050 Central bolt Engine mounting To enhance driving comfort, hydraulic engine mounts with electrical activation are used for the 8-cylinder engines. They function in the way as described in SSP 183/16. The mounts are activated by the engine control unit according to engine speed and vehicle speed.
Engine - Mechanics Engine lubrication Triple roller rocker Oil-level sensor A duocentric oil pump driven by the crankshaft via a chain replaces the previously used external gear oil pump. The duocentric oil pump extends deep into the oil sump. The low suction height means that the oil pressure can build up quickly, especially with cold-starts. SSP217_010 In the intake spindle shafts, there are 5 oil bores per triple roller rocker. Three oil bores each supply one hydraulic tappet.
Cylinder bank 1 Cylinder bank 2 B A A P Throttle B A A B Oil retention valves Throttle Spray jet valve Camshaft Oil filter module Filter element Oil pressure control valve Oil sump Oil cooler Bypass valves SSP217_011 Duocentric oil pump Slight modifications have been made to the oil circuit in the cylinder heads. The oil circuit for cylinder bank 2 shown in the illustration is the oil circuit that has been used since the introduction of the new model.
Engine - Mechanics Oil filter module (A8) Oil cooler bypass valve Coolant supply Alternator mount (part of oil module) Coolant return Oil return Oil pressure switch Oil supply SSP217_013 Filter bypass valve The oil filter module contains the oil filter and oil cooler. It is also used to hold the alternator. 12 Drain plug As was previously the case, the oil cooler is designed as a coolant-to-oil heat exchanger.
Oil filter module (A8) Coolant return Oil duct Coolant supply (from engine) Oil cooler bypass valve Plastic connection Oil return (to engine) Oil cooler Oil supply (from engine) Oil cooler supply Engine oil Oil cooler return O-ring seal SSP217_014 Coolant supply Sealing surface (Oil cooler) Coolant Oil filter module (A6) Alternator holder Oil filter cartridge For space reasons, the A6 oil filter module is fitted with an oil filter cartridge.
Engine - Mechanics Duocentric oil pump External runner Internal gear Oil pressure control valve The pitch of the internal gear and the external runner has no functional significance and is determined by production engineering factors. To ensure that the assembly functions correctly, the narrow gears must not run together on the same plane.
Notes 15
Engine - Mechanics Cooling circuit (Example: A8) Heat exchanger / valve unit Coolant temperature sender G2 and G62 Coolant pipe (return for heater, oil cooler and expansion tank) Breather pipe Return from oil cooler New coolant pipe to cylinder head (small cooling circuit) Radiator fan thermo switch F18/F54 SSP217_015 The flow direction of the coolant has been changed in the new V8 5-valve engines.
The new coolant pipe alters the coolant flow in the „small“ cooling circuit.
Engine - Mechanics Previous design: The coolant thermostat is connected to the “small coolant circuit“ via two holes in the cylinder crankcase (see Fig. 217_017). The holes are directly connected to the cylinder-head water jacket (1st cylinder) and the water jacket of the cylinder crankcase. The heated coolant flows from the 1st cylinder to the coolant thermostat.
Cylinder head Five-valve technology SSP217_020 Five-valve technology is now also being used in the V8 engines. Roller rockers are being used for the first time in the enhanced five-valve cylinder head. This considerably reduces frictional losses in the valvegear which, in turn, significantly improves efficiency. The rockers are made of die-cast aluminium in order to keep inertia forces as low as possible. As a result, the valvegear is able to function reliably at engine speeds of up to 7200 rpm.
Engine - Mechanics Roller rocker Exhaust valve Single cam Twin roller rocker SSP217_023 Roller located between rocker arms Spindle shaft, also used to supply oil Oil spray hole Exhaust valve 20.2˚ Every valve has a hydraulic valve lifter which is integrated in the rocker. The rockers are supported by a spindle shaft which is also used to supply oil to the bearings and the hydraulic valve lifters. The individual hydraulic valve lifters can be replaced without the rockers needing to be removed.
Inlet valve Double cam Hydraulic valve lifter with slide pad (hydraulic valve tappet) Spindle shaft Triple roller rocker SSP217_025 Oil duct Inlet valve 2 14.9˚ The three inlet valves are actuated via a triple roller rocker. A double cam actuates the rocker by means of two rollers between the rocker arms. Inlet valve 1 and 3 21.
Engine - Mechanics Camshaft adjuster (cylinder bank 1) Tensioning piston Chain tensioner slide pad Oil reservoir Hydraulic cylinder with switching piston Camshaft adjustment valve N205 Locking pins for starting phase Adjuster piston Slide pad adjuster The camshaft adjustment system, a feature incorporated in Audi's current range of engines, is also used in the new generation of V8-5V engines.
Lubrication and breather hole Engine off: Oil supply If there is no oil pressure, a spring-loaded locking pin is pushed into the detent slot of the adjusting piston. The adjusting piston is then locked. Locking pin A Oil return Oil reservoir B Adjusting piston B Engine start: The adjusting piston is locked until sufficient oil pressure has built up. This prevents vibrations in the chain drive and, therefore, noise generation.
Engine - Mechanics Toothed-belt drive The toothed-belt drive is identical to that of the V6-5V engine. The V8-5V engine is also fitted with a stabilising roller. The components are largely identical to those of the V6-5V engine. Stabilising roller Eccentric roller SSP217_038 Cylinder-head seal The new V8-5V engines have a multi-layer metallic cylinder-head seal already used in the 4 and 6-cylinder engines. This seal replaces the soft seal used in previous models.
Cylinder-head cover seal Seal Decoupling element (long) Cylinder head cover Spacer sleeve Profiled rubber grommet Seal cylinder head cover SSP217_040 Decoupling element (short) The thin-wall cylinder head covers are made of a die-cast magnesium alloy. A seal concept, which decouples the cylinder head cover from the cylinder head, improves the acoustics of the engine. The bolted connections of the cylinder head cover have decoupling elements.
Engine - Mechanics Exhaust manifold Manifold flange (left-hand cyl. bank) Connection for front exhaust pipe Outer shell Individual pipes reshaped for internal high pressure Cloverleaf arrangement The pipe sections and assembly of the airgap-insulated exhaust manifold have been modified. The exhaust pipes of the individual cylinders are assembled in a cloverleaf configuration for each cylinder bank (4 in 1 arrangement).
Engine - Motronic Subsystems Variable intake manifold Intake module Intake manifold flap, stage 3 Intake air (inlet) tle ot r h E-t tem s m y Fro lve s va Vacuum unit Intake manifold flap, stage 3 Holders for injectors Intake manifold flap, stage 2 (open) Vacuum unit Intake manifold flap, stage 2 Resonance tube, cyl. 5 (inlet side) SSP217_031 Increasing torque by means of variable intake manifolds is a tradition at Audi.
Engine - Motronic Subsystems Stage 1 Lower speed range Intake manifold flap Stage 3 Intake manifold flap Stage 2 When the engine is switched off, both flaps are open. SSP217_032 Stage 2 Middle speed range If the engine is idling, the two vacuum units are evacuated by the appropriate intake manifold changeover solenoid valves. The intake manifold flaps are, therefore, closed between the idling speed and the switching speed.
Effect of variable intake manifold on torque Torque 500 400 300 200 0 1500 3000 3360 4500 6000 7500 5200 Speed SSP217_035 Lower full throttle (stage 1) Middle full throttle (stage 2) Upper full throttle (stage 3) Since the maximum torque across the speed range depends primarily on the length and cross section of the intake manifold, the new three-stage variable intake manifold comes closest to producing the optimum characteristic torque curve across the speed range.
Engine - Motronic Subsystems The vacuum required to control the variable intake manifold and the secondary air system is provided by two vacuum reservoirs. If a vacuum exists in the intake manifold, the reservoirs are evacuated via a non-return valve.
Secondary air inlet valve N112 Vacuum unit, stage 3 From vacuum reservoir SSP217_052 Non-return valve Intake manifold changeover solenoid valve N261, stage 2 From vacuum reservoir Intake manifold changeover solenoid valve N156, stage 2 Vacuum unit, stage 2 31
Engine - Motronic Subsystems Secondary air system J220 N112 A G108 G62 G70 G39 B Energised Not energised V101 J299 SSP217_042 Owing to the high mixture enrichment during the cold-start and warm-up phase, an increased proportion of unburnt hydrocarbons exists in the exhaust gas during this time. The catalytic converter cannot process this high proportion of hydrocarbons because: 1. the required operating temperature of the catalytic converter has not yet been reached and 2.
Secondary air inlet valve N112 SSP217_001 Combination valve Cylinder bank 2 Connection for fresh air from secondary air pump V101 Combination valve Cylinder bank 1 Vacuum from engine Control line (vacuum or atmospheric pressure from secondary air inlet valve N112) Fresh air from secondary air pump V101 33
Engine - Motronic Subsystems Secondary air inlet valve N112 The secondary air inlet valve is an electropneumatic valve. It is activated by the Motronic control unit and controls the combination valve. It releases the vacuum stored in the reservoir to open the combination valve. Atmospheric pressure is released to close the combination valve.
Secondary air pump V101 To combination valve The secondary air pump relay J299 activated by the Motronic control unit connects the power supply for the secondary air pump motor V101. The fresh air mixed with the exhaust gas is drawn from the air filter housing by the secondary air pump and released by the combination valve. Air filter box The secondary air pump in the Audi A8 has its own air filter. The pump is integrated in the air filter housing where it draws in unfiltered air.
Engine Management System overview Altitude sender F96 (integrated in control unit) Motronic ME 7.
Active components Fuel pump relay J17 and fuel pump G6 Injectors N30, N31, N32, N33 (bank 1) Injectors N83, N84, N85, N86 (bank 2) Ignition coil N (1st cyl.), N128 (2nd cyl.), N158 (3rd cyl.), N163 (4th cyl.) Ignition coil N164 (5th cyl.), N189 (6th cyl.), N190 (7th cyl.), N191 (8th cyl.
Engine Management Function diagram 4.2/3.
30 15 X 30 15 X J17 4 X S1 S2 S3 D ST4 S117 S116 S ST3 S6 S130 ST2 S9 Y Z E45 * F36 J299 N156 N30 ST4 S10 N32 N31 N33 N83 N84 N85 N261 N112 N205 N208 N80 F47 1 F 2 CAN - BUS H S204 X 15 CAN - BUS L 30 3 N145 N144 M9 N86 M V101 M10 31 + J220 A - - + - - Y N N128 N158 N163 N164 N189 N190 - + + - - + Z G3 N191 λ M + λ + M ml G70 G6 P Q 31 P Q P Q P Q P Q P Q P Q G39 Z19 G108 Z28 G79 G185 G188 G187 G186 G163 G40 G28 G66 G
Engine Management Quick-start functions Camshaft position sensor G40 and G163 As with the V6-5V engines, the new V8-5V engines also have two sensors for determining the position of the camshaft (G40 and G163). The sender system with “quick-start rotor ring“ already used in the 4- cylinder 5-valve engines is implemented. The quick-start rotor ring has two wide and two narrow stops (two small and two large windows). If a stop is in the Hall sensor, the level at the signal output sensor is high.
* The software reference mark is the point from which the control unit commences its calculations to determine the ignition point. It is about one tooth after the hardware reference mark, which is approximately 66˚ - 67˚ cr./shaft before ignition TDC of the 1st cylinder. Signal trace of engine speed sender G28, and Hall sender G40 and G163 10 V/Div. Automatic mode 20 ms/Div G163 G40 5 V/Div.
Engine Management The ME 7.1 engine management system has to a large extent been described in SSP 198. The new functions and features of the system used in the V8-5V engine are dealt with below. Electronic throttle function Apart the following features, the electronic throttle functions are identical to those described in SSP 198. Accelerator pedal Kickdown switch The pedal sender is used in the Audi A8 and the accelerator pedal module in the Audi A6 to determine the requirements of the driver.
Accelerator pedal module (Audi A6) No separate switch is used to provide kickdown information. In the case of automaticgearbox vehicles, the accelerator pedal stop is replaced by a pressure element. The pressure element generates a “mechanical pressure point“ which gives the driver the “kickdown feeling“. If the driver activates the kickdown, the fullthrottle voltage of the accelerator pedal position senders is exceeded.
Engine Management CAN bus interfaces Engine control unit Intake air temperature Brake light switch Brake pedal switch Throttle valve angle Electronic throttle warning lamp info Driver torque range Emergency running programmes (info via self-diagnosis) Accelerator pedal position CCS switch positions CCS target speed Altitude information Kickdown information Switch off compressor Compressor ON/OFF (check-back signal from bidirectional interface) Fuel consumption Coolant temperature Clutch pedal switch Idle d
In the Audi A8, data between the engine control unit and the other control units is, with the exception of a few interfaces, exchanged via the CAN system. The system overview shows the information which is provided by the engine control unit via the CAN bus, and received and used by the connected control units. Detailed information concerning the CAN data bus can be found in SSP 186. The following two examples simplify the complexity of the CAN bus network.
Engine Management Additional signals/ interfaces In the Audi A8, the following interfaces also exist for data exchange via CAN bus: Pin 67 Pin 43 Pin 41 Pin 40 Crash signal K-line/diagnostic connection Compressor ON/OFF Air conditioner requirement signal Most of the interfaces and additional signals of the ME 7.1 are described in SSP 198. Only the new interfaces and additional signals are dealt with below.
Crash signal Signal traces for crash signal using oscilloscope function of VAS 5051 5 V/Div. Automatic mode 0,1 s/Div. T Standard signal Crash triggering SSP217_058 In the event of a crash where the belt tensioners/airbags are triggered, the engine control unit deactivates actuation of the fuel pump relay. This prevents excessive quantities of fuel escaping if the fuel system is damaged. In the event of a crash, the signal ratio is inverted for a defined period of time.
Engine Management Self-diagnosis The crash signal is checked with respect to the plausibility of the crash signal and voltage. The fuel shut-off system will not be incorporated in the Audi A6 and A8 until model year 2000. Effect of fault If the “crash shut-off“ fault is stored in the engine control unit and is not erased, the fuel pump is not primed with fuel when the ignition is switched on (no precompression is generated in the fuel system). This may result in delayed starting of the engine.
Service A number of new special tools are required by the Service department for repairing the V8-5V engine. Thrust pad for crankshaft oil seal Order No.T40007 SSP213_007 Tensioning roller spanner Order No.T40009 SSP213_008 Camshaft retainer Order No.
Notes 50
Dear Reader, This self-study programme has allowed you to familiarise yourself with the new technical features of the V8-5V engine. Our aim is to make the content of the self-study programme material as interesting as possible. This is why we want to give you the opportunity to tell us your opinions and suggestions for future self-study programmes. The following questionnaire is intended to assist you in doing this. Send your comments and suggestions to the fax number 0049/841 89 36 36 7.
217 217 Service. The V8-5V Engine Construction Features and Functions Self-Study Programme 217 All rights reserved. Subject to technical modifications. AUDI AG Abteilung I/VK-5 D-85045 Ingolstadt Fax 0841/89-36367 940.2810.36.
