Technical training. Product information. S55 Engine BMW Service BimmerFile.com General information Symbols used The following symbol is used in this document to facilitate better comprehension or to draw attention to very important information: A Contains important safety information and information that needs to be observed strictly in order to guarantee the smooth operation of the system. Information status and national-market versions BMW Group vehicles meet the requirements of the highest safety and quality standards. Changes in requirements for environmental protection, customer benefits and design render necessary continuous development of systems and components. Consequently, there may be discrepancies between the contents of this document and the vehicles available in the training course. This document basically relates to the European version of left-hand drive vehicles. Some operating elements or components are arranged differently in right-hand drive vehicles than shown in the graphics in this document. Further differences may arise as a result of the equipment specification in specific markets or countries. Additional sources of information Further information on the individual topics can be found in the following: • Owner's Handbook • Integrated Service Technical Application Contact: conceptinfo@bmw.de ©2014 BMW AG, Munich Reprints of this publication or its parts require the written approval of BMW AG, Munich The information contained in this document forms an integral part of the technical training of the BMW Group and is intended for the trainer and participants in the seminar. Refer to the latest relevant information systems of the BMW Group for any changes/additions to the technical data. Information status: March 2014 BV-72/Technical Training BimmerFile.com S55 Engine Contents 1. Introduction.1 1.1. Highlights.1 1.1.1. Technical data.2 1.1.2. Full load diagram.4 1.2. S55/N55 new features/changes.5 1.2.1. Overview.5 1.2.2. Comparison of the N55 engine/S55 engine.6 2. Engine History.10 2.1. Variants of the BMW M3 engines.10 3. Engine Identification.11 3.1. Engine designation and engine identification.11 3.1.1. Engine designation.11 4. Engine Mechanical.13 4.1. Engine housing.13 4.1.1. Engine block.13 4.1.2. Cylinder head.17 4.1.3. Cylinder head cover.18 4.1.4. Engine cover.24 4.1.5. Oil pan.25 4.2. Crankshaft.26 4.2.1. Crankshaft with bearings.26 4.2.2. Connecting rod with bearing.27 4.2.3. Piston and piston rings.31 4.3. Camshaft drive.33 5. Valvetrain.34 5.1. Design.34 5.1.1. Camshafts.35 5.1.2. Timing.36 5.1.3. Intake and exhaust valves.37 5.1.4. Valve springs.37 5.2. Valvetronic.38 5.2.1. VANOS.38 5.2.2. Valve lift control.40 6. Belt Drive & Auxiliary Components.46 6.1. Belt drive.46 6.1.1. Vibration damper.47 BimmerFile.com S55 Engine Contents 7. Oil Supply.48 7.1. Oil circuit.48 7.1.1. Oil passages.48 7.1.2. Oil return.52 7.1.3. Oil pump and pressure control.54 7.1.4. Suction pump.55 7.1.5. Oil filter and engine oil cooling.60 7.1.6. Oil spray nozzles.61 7.1.7. Engine oil pressure monitoring.61 8. Air Intake & Exhaust Emission Systems.62 8.1. Air intake system.62 8.1.1. Overview.62 8.1.2. Intake manifold.66 8.1.3. Tank ventilation system.67 8.2. Exhaust emission system.68 8.2.1. Overview.68 8.2.2. Exhaust manifold.70 8.2.3. Lightweight construction of heat shields for exhaust manifold.72 8.2.4. Exhaust turbocharger.73 8.2.5. Catalytic converter.75 9. Vacuum System.76 9.1. Design.76 9.1.1. Vacuum pump.77 10. Fuel System.78 10.1. Overview.78 10.1.1. Low pressure fuel sensor.79 10.1.2. High pressure fuel pumps.80 10.1.3. Fuel Injectors.82 11. Cooling System.87 11.1. Overview.87 11.2. Engine cooling.90 11.2.1. Coolant passages.92 11.2.2. Cooling circuit, exhaust turbochargers.93 11.3. Charge air cooling.95 12. Engine Electrical System.97 12.1. Electrical system connection.97 BimmerFile.com S55 Engine Contents 12.1.1. Overview.97 12.1.2. System wiring diagrams.98 12.1.3. Engine control unit.101 12.2. Functions.101 12.2.1. Fuel supply.101 12.2.2. Charging pressure control.101 12.3. Sensors.102 12.3.1. Crankshaft sensor.102 12.3.2. Ignition coil and spark plug.103 12.3.3. Oil pressure sensor.104 12.3.4. Oxygen sensors.104 12.3.5. Hot film air mass meter.106 12.4. Actuators.106 12.4.1. Valvetronic servomotor.106 12.4.2. Fligh-pressure fuel injection valve.108 13. Service Information.Ill 13.1. Engine mechanics.Ill 13.1.1. Engine housing.Ill 13.2. Fuel preparation.112 13.2.1. Overview.112 BimmerFile.com S55 Engine 1. Introduction 1.1. Highlights The S55 engine is the successor to the S65 engine. Similar to the engines in the X5M, X6M, Fix M5/ M6 and F06 M6 with S63 engine, the S55 is based on a production engine of BMW AG. As the engine identification highlights, the S55 engine is based on the N55 engine. In contrast to the previous model, with its V8 naturally aspirated engine, the new BMW M3 and M4 Coupe are driven by a 3.0 liter, 6 cylinder gasoline engine with M TwinPower turbo technology. Technical updates and M GmbH modifications make the engine suitable for motor racing. Thanks to turbocharging and the high-speed concept, the new M engine impresses with an unforeseen power development of 317 kW/425 HP and, in contrast to the S65, is readily available at considerably lower engine speeds. The maximum torque, a sign of the power development felt by the driver, increased by 37% from 400 Nm/295 Ib-ft to 550 Nm/406 Ib-ft, and is available across almost the entire usable engine speed range. Even though the S55 has increased power output, with the help of BMW EfficientDynamics measures, fuel consumption and CO 2 emissions were reduced by 28% and 26% respectively. As the S55 engine is based on the N55 engine, 75% of the engine components were adopted from the N55 production engine and the other 25% of the engine components are new developments. All the technical data is above that of the predecessor. The S55 engine also contributes to the overall concept of intelligent lightweight construction in the F80/F82. Through the intelligent use of material, the weight of the S55 engine was reduced by 3% in comparison to the S65 engine. 1 BimmerFile.com S55 Engine 1. Introduction 1.1.1. Technical data S55 engine, overall view Model Unit E92 M3*** F80/F82*** Engine S65B4000 S55B30T0 Design V8 R6 Displacement [cm 3 ] 3,999 2,979 Bore hole/Stroke [mm] 92/75.2 84.0/89.6 Power [kW/HP] 309/414 317/425 at speed [rpm] 8,300 5,500 - 7,300 Power output per liter [kW/l] 77.3 106.4 Torque [Nm/lb-ft] 400/295 550/406 at speed [rpm] 3,900 1,850-5,500 Compression ratio [e] 12:1 10.2: 1 Valves per cylinder 4 4 Fuel consumption [1/100 km] 11.2 8.8 C0 2 emissions [grams per kilometre] 263 204 2 BimmerFile.com S55 Engine 1. Introduction Model Unit E92 M3*** F80/F82*** Digital Engine Electronics MSS60 MEVD17.2.G Exhaust emissions legislation LEV II ULEV2 Engine weight [kg/lbs] 212/467 205/452 Maximum speed [km/h / mph] 250*/155* 250*/155* Acceleration 0-60 mph [s] 4.6 4.1 Vehicle curb weight US Vehicle [kg/lbs] 1,600/2527 1,675/3692 F80 1,606/3540** 1,631 /3595*** F82 1,601 /3529** 1,626/3584*** * = Electronically regulated ** = Manual gearbox *** = with M Double-clutch Transmission with Drivelogic (SA 2MK) 3 BimmerFile.com S55 Engine 1. Introduction 1.1.2. Full load diagram In comparison to the predecessor, the S55 engine features lower fuel consumption with higher power and torque output. [Nm] 700 650 ♦ 425 hp / 317 kW@> 7300 1/min [kW] 350 325 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 [1/min] O* . . 9 _ .......... <9 S55B30T0 S65B4000 Full load diagram E9x M3 with S65B40 engine in comparison to the F80/F82 M3/M4 Coupe with S55B30T0 engine 4 BimmerFile.com S55 Engine 1. Introduction 1.2. S55/N55 new features/changes 1.2.1. Overview 5 BimmerFile.com S55 Engine 1. Introduction Index Explanation 1 Cylinder head cover 2 Cylinder head 3 Cylinder head gasket 4 Crankcase 5 Crankshaft drive 6 Bedplate 7 Engine oil sump gasket 8 Oil supply 9 Oil pan 1.2.2. Comparison of the N55 engine/S55 engine Engine Mechanics Component New development Identical in concept Comment Cylinder head cover • Deletion of vacuum reservoir Crankcase ventilation same as N55 engine Cylinder head gasket • Revision of the cylinder head gasket, at water through-passages for higher coolant flow rate in the S55 engine Crankcase • Modified for bi-turbo Closed Deck design Cylinder walls are LDS-coated Weight saving of approx. 5 lbs Crankshaft with bearings • Weight saving of approx. 4 lbs in comparison to the N55B3000 (M235i) steel crankshaft Modification of main bearings and crankshaft to the high-speed concept Connecting rod • Connecting rod bore hole in small connecting rod eye Lead-free connecting rod bearing shells Common part N20-N55 engine Piston and wrist pin • Modifying of the piston and wrist pin to the high-speed concept 6 BimmerFile.com S55 Engine 1. Introduction Valve Gear Component New development Identical in concept Comment Intake valves and exhaust valves • Material change VANOS • Solenoid valves with integrated non¬ return valve and 3 strainers Increased adjustment speed and reduced susceptibility to dirt Fully variable valve lift adjustment • Integrated in the cylinder head and revised Brushless servomotor (3rd generation) Position sensor for eccentric shaft integrated in the servomotor Optimization of work curve for the valve opening, modified to the high-speed concept Belt Drive and Auxiliary Components Component New development Identical in concept Comment Belt drive • Vibration damper for adaptation to the high-speed concept Modified for the powertrain, mechanical coolant pump Additional belt tensioner between crankshaft and a/c compressor Oil Supply Component New development Identical in concept Comment Oil supply • Magnesium oil pan, weight saving of approx. 2.2 lbs Additional internal oil pan cover Oil pump with tandem output Additional oil extraction at front with 2nd oil pump Additional oil extraction, exhaust turbocharger Oil filter module 7 BimmerFile.com S55 Engine 1. Introduction Air Intake and Exhaust Emission systems Component New development Identical in concept Comment Exhaust turbocharger • Bi-exhaust turbocharger with electrical wastegate valve Mono-scroll concept Two exhaust manifolds and two exhaust turbochargers, each bank has its own unit (manifold/turbocharger). Air intake duct • New air intake duct for use of indirect charge air cooling New clean air ducts Modified intake silencer Exhaust system • Optimized for minimal exhaust gas pressure Electrical exhaust flaps Active Sound Design (ASD) in the passenger compartment Heat shields Upstream catalytic converter • Heat shields made from AIMg3 Weight saving of approx. 3.3 lbs Vacuum System Component New development Identical in concept Comment Vacuum pump • Revised, similar to N55 engine Single-stage vacuum pump Fixture for high pressure pumps Fuel System Component New development Identical in concept Comment Injectors • Solenoid valve injectors adapted to ULEV2 Injectors for CVO support for ULEV2 High pressure pump • Double high pressure pump 8 BimmerFile.com S55 Engine 1. Introduction Cooling System Component New development Identical in concept Comment High-temperature circuit for engine cooling • Revised for high-performance operation without power restriction Mechanical coolant pump Additional electric coolant pump for exhaust turbochargers Map thermostat Low-temperature circuit for charge air cooling • Indirect charge air cooling with 2 heat exchangers Separate cooling water circuit Electric coolant pump Engine Electrical System Component New development Identical in concept Comment Digital Engine Electronics (DME) • MEVD 17.2.G with CVO function Secured at the intake air system and cooled via the intake air Software adaptation to S55 engine Hot film air mass meter • Hot film air mass meter 7 Oxygen sensor • Adopted from the N55 engine (LSU ADV) Monitoring sensor LSF XF0UR/ULEV2 Spark plugs • New spark plug for S55 engine 9 BimmerFile.com S55 Engine 2. Engine History 2.1. Variants of the BMW M3 engines Engine Version Series Displacement in cm 3 Stroke/ Bore hole in mm Power in kW/HP at Torque in Nm at S14B23 US E30 2,302 84.0/93.4 143/192 6,750 230 4,750 S50B30 US E36 2,990 85.8/ 86.06 177/240 6,000 305 4,250 S52B32 US E36 3,152 89.6/86.4 177/240 6,000 320 3,800 S54B32 US E46 3,246 91.0/87.0 248/333 7,900 355 4,900 S65B40 US E9x 3,999 75.2/92.0 309/414 8,300 400 3,900 10 BimmerFile.com S55 Engine 3. Engine Identification 3.1. Engine designation and engine identification 3.1.1. Engine designation In the technical documentation, the engine designation is used to ensure distinct identification of the engine. The technical documentation also contains the short form of the engine designation S55, which only indicates the engine type. Position Meaning Index/Explanation 1 Engine developer M, N = BMW Group P = BMW M Sport S = BMW M GmbH W = External developer 2 Engine type 1 = R4 (e.g. N12) 4 = R4 (e.g. N43) 5 = R6 (e.g. N53) 6 = V8 (e.g. N63) 7 = V12 (e.g. N73) 8 = V10 (e.g. S85) 3 Change to the basic engine concept 0 = Basic design 1 to 9 = Modifications, e.g. to combustion process 4 Working method or fuel type and possibly installation position B = gasoline, longitudinal installation D = Diesel, longitudinal installation H = Hydrogen 5 Displacement in liters 1 = 1 liter + 6 Displacement in 1/10 liter 8 = 0.8 liters = 1.8 liters 7 Performance class K = Lowest U = Lower M = Medium 0 = Upper (standard) T = Top S = Super 8 Revision relevant to approval 0 = New design 1-9 = Revision 11 BimmerFile.com S55 Engine 3. Engine Identification Breakdown of the S55 engine designation Index Explanation S BMW M GmbH development 5 6-cylinder in-line engine 5 Engine with direct fuel injection, Valvetronic and exhaust turbocharger B gasoline engine, longitudinal installation 30 3.0 liter displacement T TOP performance class 0 New development 12 BimmerFile.com S55 Engine 4. Engine Mechanical 4.1. Engine housing The engine housing includes the engine block (crankcase and bedplate), cylinder head, cylinder head cover, oil sump, and gaskets. 4.1.1. Engine block The engine block is made from die-cast aluminum alloy (AlSi 7Cu0.5Mg) and consists of a crankcase and bedplate. Crankcase and bedplate The crankcase of the S55 engine is designed as a Closed Deck crankcase, while the N55 is an open deck design. It does not have moulded cylinder liners made from cast iron like the N55 engine, but LDS-coated aluminium cylinder liners. For more information on electric arc wire spraying (LDS) please refer to the "ST 1111 N20 Engine" Technical Reference Manual. This material combination lightened the S55 engine block by 2.2kg/4.85lbs in comparison to the production engine (N55). This weight savings benefits the intelligent lightweight construction of the F80/F82-M3/M4 Coupe. With a closed deck crankcase design, the openings for the crankcase cover plate are reduced and result in the increase of overall crankcase rigidity. As a mechanical coolant pump is used in the S55 engine, the coolant ducts and the fixture for the coolant pump are inserted in the crankcase. In addition, the mounting points for the S55 engine-specific auxiliary components have been adapted to the crankcase. 13 BimmerFile.com S55 Engine 4. Engine Mechanical S55 engine, Closed Deck crankcase Index Explanation 1 Fixture, engine coolant pump 2 Engine oil return, exhaust side 3 Engine oil return, intake side 4 Coolant ducts 5 Cylinder liners, LDS-coated 14 BimmerFile.com S55 Engine 4. Engine Mechanical S55 engine, ventilation holes in the crankcase The crankcase has longitudinal ventilation holes bored between the lower chambers of the cylinders. These ventilation holes improve the pressure equalization of the oscillating air columns created by the up and down strokes of the pistons. 15 BimmerFile.com S55 Engine 4. Engine Mechanical S55 engine, bedplate from above 9 V o The crankcase and bedplate also have the necessary connections for the two exhaust turbocharger coolant and oil supply/return lines. 16 BimmerFile.com S55 Engine 4. Engine Mechanical 4.1.2. Cylinder head The cylinder head of the S55 engine has been modified to motor racing requirements. The basic structure of the cylinder head is similar to that of the N55 engine. The S55 6-cylinder engine also uses direct fuel injection with exhaust turbocharging and Valvetronic. The cylinder head is very compact and is equipped with the 3rd generation Valvetronic. A The combination of exhaust turbocharger, Valvetronic and direct fuel injection is known as Turbo Valvetronic Direct Injection (TVDI). TVDI technology reduces C0 2 emission and fuel consumption by 3-6%. The connections for the VANOS non-return valves were removed like in the N55 engine, as they have been integrated in the solenoid valves. The cylinder head also features coolant passages around the injectors for indirect cooling. S55 engine, cylinder head 17 BimmerFile.com S55 Engine 4. Engine Mechanical 4.1.3. Cylinder head cover Design The cylinder head cover is a modified part from the N55 engine. Unlike the N55 cylinder head cover, the S55 cylinder head cover no longer has a built in accumulator for the vacuum system. The general operating principle of the crankcase ventilation in the cylinder head cover has not changed from a technical viewpoint. All the components for crankcase ventilation and the blow-by ducts are integrated in the cylinder head cover. The integrated non-return valves ensure that the blow-by gases are reliably supplied to the intake air in both engine modes (NA and Boost). The S55 engine is equipped with a vacuum-controlled crankcase ventilation system. A vacuum of approximately 38 mbar is regulated. S55 engine, cylinder head cover with crankcase ventilation 18 BimmerFile.com S55 Engine 4. Engine Mechanical Index Explanation 1 Housing without vacuum reservoir 2 Connection, Valvetronic servomotor 3 Blow-by gas duct with settling chamber, impact plate, pressure control valve and non-return valves 4 Pressure control valve 5 Oil filling lid opening 6 Housing, chain drive 7 Crankcase ventilation line A The crankcase ventilation line cannot be replaced individually, only together with the cylinder head cover. The blow-by gases reach a settling chamber in the cylinder head cover through an opening in the rear of the cover. The blow-by gases are then directed through holes on an impact plate which the oil hits, at a high flow rate, and drains down. The blow-by gases, cleaned of oil, now flow via the pressure control valve through the non return valves (depending on the operating mode) to the charge air intake pipe before the exhaust turbocharger or to the intake manifold before the intake valves. The separated oil is directed via return duct to the oil sump. Function Naturally Aspirated Mode The standard function can only be utilized while there is a vacuum in the intake manifold, i.e. in naturally aspirated mode. In naturally aspirated mode, the non-return valves in the blow-by duct of the cylinder head cover are opened by the vacuum in the intake plenum and the blow-by gases are drawn off via the pressure control valve. The vacuum simultaneously closes the second non-return valve in the duct to the charge-air intake line. Blow-by gases are routed directly into the cylinder head intake ports via the distribution rail integrated in the cylinder head cover. 19 BimmerFile.com S55 Engine 4. Engine Mechanical S55 engine, crankcase ventilation, naturally aspirated mode Index Explanation A Ambient pressure B Vacuum C Exhaust gas D Oil E Blow-by gas 1 Air cleaner 2 Intake manifold 20 BimmerFile.com S55 Engine 4. Engine Mechanical Index Explanation 3 Perforated plates 4 Oil return duct 5 Crank chamber 6 Oil sump 7 Oil return duct 8 Exhaust turbocharger 9 Oil drainage valve 10 Charge-air intake line 11 Hose for charge-air intake line 12 Non-return valve 13 Pressure control valve 14 Throttle valve 15 Non-return valve 16 Duct in cylinder head and cylinder head cover Boost Mode Once the pressure in the intake manifold rises, it is no longer possible for the blow-by gases to be introduced via passages in the cylinder head. Otherwise, this would create the risk of the charging pressure being introduced into the crankcase. A non-return valve in the blow-by duct of the cylinder head cover closes the duct to the intake plenum and thereby protects the crankcase against excess pressure. The now increased demand for fresh air generates a vacuum in the clean air pipe between the exhaust turbocharger and the intake silencer. This vacuum is sufficient to open the non-return valve and to extract the blow-by gases via the pressure control valve. 21 BimmerFile.com S55 Engine 4. Engine Mechanical S55 engine, crankcase ventilation, turbocharged mode Index Explanation A High pressure B Vacuum C Exhaust gas D Oil E Blow-by gas 1 Air cleaner 2 Intake manifold 22 BimmerFile.com S55 Engine 4. Engine Mechanical Index Explanation 3 Perforated plates 4 Oil return duct 5 Crank chamber 6 Oil sump 7 Oil return duct 8 Exhaust turbocharger 9 Oil drainage valve 10 Charge-air intake line 11 Hose for charge-air intake line 12 Non-return valve 13 Pressure control valve 14 Throttle valve 15 Non-return valve 16 Duct in cylinder head and cylinder head cover A If there is a complaint of high oil consumption and oil is found in the turbocharger, it should not be immediately concluded that the turbocharger is faulty. If oil is present in the fresh air pipe before the turbochargers, then the entire engine must be checked for leaks. The cause of an excessive blow- by gas flow rate may be faulty gaskets or crankshaft seals. Loose crankshaft seals may generate oil consumption of up to 31/1000 km (3.2qt/621miles). 23 BimmerFile.com S55 Engine 4. Engine Mechanical 4.1.4. Engine cover The engine cover was modified to the S55 engine. The engine cover consists of two independent components: • the ignition coil cover • the corrosion protection cover With this design, the engine cover weighs 960 grams (2.1 lbs) less than the N55 engine cover. 9 S55 engine, engine cover 5 Index Explanation 1 Corrosion protection cover 2 Ignition coil cover 24 BimmerFile.com S55 Engine 4. Engine Mechanical 4.1.5. Oil pan The oil pan of the S55 engine is made from magnesium and results in a weight savings of approximately 1000 grams (2.2lbs) in comparison to the aluminium oil pan in the N55 engine. An additional cover in the oil pan restricts the oil movements during longitudinal and lateral acceleration. S55 engine, oil pan Index Explanation A Oil pan, inner B Oil pan from the outside 1 Additional oil pan lid 2 Oil separator The sealing of the oil pan with the crankcase is done with a metal gasket with rubber inserts and aluminium screws. Due to the electrochemical corrosion between aluminium and magnesium the same operations and repair instructions must be observed as for other engines with these material combinations. A cover plate is installed between the crankcase/oil pan and transmission to protect against corrosion. A_ Do not reuse aluminium screws. They must be replaced after single use. 25 BimmerFile.com S55 Engine 4. Engine Mechanical 4.2. Crankshaft 4.2.1. Crankshaft with bearings Crankshaft While maintaining a lightweight construction, the forged steel crankshaft was adapted to the high¬ speed concept and increased power. At 21.1 kg (46.5 lbs), the crankshaft of the S55 engine is approximately 1.8 kg (4 lbs) lighter than the steel crankshaft of the N5530B0 (M235i) engine and 1 kg (2.2 lbs) heavier than the cast iron crankshaft of the N55B30M0 (standard) engine. The crankshaft is made from a steel alloy (42CrMoS4 Mod) and is then nitrocarburized (hardened). The counterweight arrangement is symmetrical, while the cast iron N55 engine crankshaft counterweight arrangement is asymmetrical. There is no increment wheel installed on the crankshaft, similar to the N55 engine. The crankshaft speed is determined by a magnetic wheel and crankshaft speed sensor, based on the hall principle. The timing chains are connected by a M18 central bolt. S55 engine, crankshaft Index Explanation 1 Connecting rod bearing 2 Counterweights 3 Main bearing 26 BimmerFile.com S55 Engine 4. Engine Mechanical Crankshaft main bearing The crankshaft main bearings were modified, from the N55 engine, in order to satisfy the high¬ speed concept requirements. The bearings are lead-free. A three-material (Kolbenschmidt S703C) electroplated bearing is used for the lower bearing shells. For the upper bearing shells, a two-material bearing made from aluminium (Kolbenschmidt R25) is used. The thrust bearing is located at the fourth bearing position. 4.2.2. Connecting rod with bearing The connecting rod of the S55 engine has an inside diameter of 144.35 mm. Like in the N20-N55 engines, the small end of the connecting rod has a specially shaped bore. It is machined wider on the lower edges. This design evenly distributes the force acting on the wrist pin over the entire surface of the rod bushing and reduces the load on the edges, as the piston moves downward, during the power stroke. S55 engine, small connecting rod end Index Explanation 1 Bushing 2 Connecting rod 27 BimmerFile.com S55 Engine 4. Engine Mechanical The following graphic shows surface load on a standard connecting rod without a shaped bore. Due to the pressure on the piston during combustion, most of the force is transferred by the wrist pin to the edges of the small connecting rod bushing. S55 engine, small connecting rod end without shaped bore Index Explanation A Low surface load B High surface load The graphic below illustrates the small connecting rod end with the shaped bore. The force is distributed across a larger surface area and the load on the edge of the bushing is reduced considerably. 28 BimmerFile.com S55 Engine 4. Engine Mechanical S55 engine, small connecting rod end with shaped bore Index Explanation A Low surface load B High surface load Lead-free connecting rod bearing shells, like in the N20-N55 engine, are used for the large connecting rod ends. The rod side material G-488 is used and on the cap side the material G-444 is used. The bolts for the S55, N55 and N54 engine connecting rods are the same (M9 x 47). 29 BimmerFile.com S55 Engine 4. Engine Mechanical S55 engine, connecting rod bearing Index Explanation 1 Piston 2 Connecting rod 3 Crankshaft 4 Connecting rod bearing 30 BimmerFile.com S55 Engine 4. Engine Mechanical 4.2.3. Piston and piston rings The piston was modified in its styling and material properties to the higher requirements of the high¬ speed concept in the S55 engine. A full slipper skirt piston manufactured by the Mahle company is used. The piston is made from an aluminium alloy (AISi12Cu4Ni2Mg). This alloy is particularly suitable for high-performance gasoline engines. The piston skirt is Grafal-coated. This is necessary due to the LDS-coated cylinder liners. The piston diameter is 84 mm. The first piston ring is a nitride plain rectangular compression ring. The second piston ring is a taper-faced piston ring. The oil scraper ring is a nitride ES oil scraper ring. S55 engine, piston with wrist pin and piston rings Index Explanation 1 Plain compression ring 2 Taper-faced piston ring 3 ES oil scraper ring 31 BimmerFile.com S55 Engine 4. Engine Mechanical Wrist pin The wrist pin was revised accordingly to the higher requirements in the S55 engine. The material and the strength was upgraded to satisfy the high-speed concept. A wrist pin with restricted volume change and a 22 mm diameter is used. This wrist pin is made from a steel alloy (16MnCr5) and then case-hardened. Combustion chamber geometry The following graphic shows the arrangement of the individual components around the combustion chamber. From the graphic, one can see that the BMW high precision injection (HPI) is not used, but rather a Bosch solenoid valve fuel injector with a multi-hole nozzle. This fuel injector is specially adapted to the combination of turbocharging and Valvetronic III. For a clearer overview, a set of valves has been removed in the graphic. © @ © ® ® S55 engine, combustion chamber with components 32 BimmerFile.com S55 Engine 4. Engine Mechanical Index Explanation 1 Valve seat, exhaust valve 2 Exhaust valve 3 Spark plug 4 Injector 5 Intake valve 6 Valve seat, intake valve 7 Piston 4.3. Camshaft drive The camshaft drive corresponds to the camshaft drive of the N55 engine. 33 BimmerFile.com S55 Engine 5. Valvetrain 5.1. Design The following graphic shows the design of the cylinder head on the S55 engine with Valvetronic III and direct fuel injection. S55 engine, overview of valve gear Index Explanation 1 VANOS unit, exhaust camshaft 2 Injector shaft 3 Spark plug shaft 4 Exhaust-bearing strip 5 Valvetronic servomotor 6 Torsion spring 7 Gate 34 BimmerFile.com TO 14-0200 S55 Engine 5. Valvetrain Index Explanation 8 Eccentric shaft 9 Intermediate lever 10 Roller cam follower 11 Valve spring 12 Intake camshaft 13 Oil spray nozzle 14 Passage for introduction of blow-by gas 15 VANOS unit, intake camshaft 5.1.1. Camshafts In the N54 engine, cast or lightweight construction camshafts have been used simultaneously. In a N54 engine the use of lightweight construction camshafts and cast camshafts or a mixed installation is possible. In the S55 engine, similar to the N55 engine, only lightweight construction camshafts are used. The lightweight construction camshafts for the S55 engine are manufactured by hydroforming. The exhaust camshaft has bearing races and is enclosed in a camshaft housing. Oil foaming during operation is reduced by the camshaft housing. S55 engine, camshaft made from hydroforming Index Explanation A Intake camshaft B Exhaust camshaft 1 Corrugated tubing 2 Cam in shell shape 35 BimmerFile.com S55 Engine 5. Valvetrain 5.1.2. Timing mm S55 engine, timing diagram N55B30M0 S55B30T0 Intake valve diameter [mm] 32 32 Exhaust valve diameter [mm] 28 28 Maximum valve lift, intake/exhaust valve [mm] 9.9/9.7 9.9/9.7 Steering axis inclination, intake camshaft (VANOS adjustment range) [crankshaft degrees] 70 70 Steering axis inclination, exhaust camshaft (VANOS adjustment range) [crankshaft degrees] 55 55 Camshaft adjustment, intake [crankshaft degrees] 120-50 120-50 Camshaft adjustment, exhaust [crankshaft degrees] 115-60 115-60 Opening period Intake camshaft [crankshaft degrees] 255 255 Opening period Exhaust camshaft [crankshaft degrees] 261 261 36 BimmerFile.com S55 Engine 5. Valvetrain 5.1.3. Intake and exhaust valves The valve stem of the intake valves has a diameter of 5 mm and the exhaust valves have a diameter of 6 mm. The reason for the larger diameter is that the exhaust valve is hollow and is filled with sodium, which improves heat transfer. In addition, the valve seat of the exhaust valve is reinforced. 5.1.4. Valve springs Due to the different shaft diameters between the intake and exhaust valves, the valve springs are different. 37 BimmerFile.com S55 Engine 5. Valvetrain 5.2. Valvetronic 5.2.1. VANOS Overview The VANOS of the S55 engine corresponds in its design and function to that of the N55 engine. In the N55 engine the VANOS was optimized in comparison to the N54 engine. This optimization now provides for even faster VANOS unit adjustment speeds. The modification has also further reduced the system's susceptibility to fouling. S55 engine, VANOS with oil supply 38 BimmerFile.com S55 Engine 5. Valvetrain Index Explanation 1 Main oil duct 2 VANOS solenoid valve, intake side 3 VANOS solenoid valve, exhaust side 4 Chain tensioner 5 VANOS unit, exhaust side 6 VANOS unit, intake side The camshaft sensor wheels are now pure sheet metal “deep-drawn” parts and are no longer made from two parts. This measure increases the manufacturing accuracy and reduces the manufacturing costs. S55 engine, camshaft sensor wheel Index Explanation A General view of rear side B General view of front VANOS solenoid valves The VANOS solenoid valves used in the N55 engine are identical to those in the S55 engine. Three strainers at each VANOS solenoid valve ensure trouble-free functioning and reliably prevent the VANOS solenoid valves from jamming due to dirt particles. 39 BimmerFile.com S55 Engine 5. Valvetrain 5.2.2. Valve lift control Overview As can be seen from the following graphic, the installation location of the servomotor has not changed in comparison to the N55 engine. Another special feature is that the eccentric shaft sensor no longer sits at the eccentric shaft, but has been integrated in the servomotor. Due to the higher engine speeds of up to 7,600 rpm, the work curve of the eccentric shaft has been modified. S55 engine, valve lift control Index Explanation 1 Valvetronic servomotor 2 Oil spray nozzle 3 Eccentric shaft 4 Minimum limit position 5 Maximum limit position 40 BimmerFile.com S55 Engine 5. Valvetrain Valvetronic III is used. The differences between Valvetronic III and Valvetronic II are in the arrangement of the Valvetronic servomotor and the Valvetronic sensor. As in Valvetronic II, the turbulence level is increased at the end of the compression cycle for the purpose of optimizing the mixture formation with the use of phasing and masking measures. This movement of the cylinder charge improves the combustion during partial load operation and in catalytic converter heating mode. The quench areas also contribute to the mixture formation. Phasing Phasing results in a lift difference between both intake valves of up to 1.8 mm in the lower partial load range. The fresh air drawn in is thus distributed unequally. Masking Masking refers to the styling of the valve seat area. This styling ensures that the incoming fresh air is aligned so that the desired cylinder charging movement is achieved. The advantage of these measures is that the combustion delay (retardation) is reduced by approximately 10° of crankshaft rotation. The combustion process is quicker and a larger valve overlap can be realized. The NO x emissions can thus be reduced significantly. 41 BimmerFile.com S55 Engine 5. Valvetrain S55 engine, combustion chamber roof Index Explanation 1 Crushing area 2 Exhaust valve 3 Spark plug 4 Injector 5 Intake valve 6 Masking 7 Crushing area The following graphic shows the effect of the previously described measures. An improved and quicker combustion process is enabled with these measures, in the red area. Technically, this is known as "turbulent kinetic energy". 42 BimmerFile.com S55 Engine 5. Valvetrain Influence of phasing and masking on the flow in the combustion chamber Index Explanation A Valvetronic 1 B Valvetronic II + III with advance and masking TKE Turbulent kinetic energy Engine response characteristics can be improved with the combination of Valvetronic III, direct fuel injection and turbocharging. The response characteristics up to the naturally aspirated engine full load are shortened, as with the naturally aspirated engine with Valvetronic, as the filling procedure of the intake manifold is deleted. The subsequent torque build-up as the turbocharger starts up can be accelerated at low engine speeds with a partial lift adjustment. The flushing of the residual gas leads to a quicker build-up of the torque. 43 BimmerFile.com S55 Engine 5. Valvetrain Valvetronic A brushless direct current motor is used, as in the N55 engine. The Valvetronic servomotor has the following special features: • Open concept (engine oil is supplied directly to the motor) • The eccentric shaft angle is determined by angle increments from the integrated sensor system • Power consumption reduced by approximately 50% • Higher actuating dynamics (e.g. cylinder-specific adjustment, idle speed control, etc.) • Lightweight design - approximately 600 grams The third generation of the Valvetronic servomotor also includes the sensor for identifying the position of the eccentric shaft. Another special feature is that engine oil flows through and around the Valvetronic servomotor. An oil spray nozzle ensures that the worm gear is lubricated for the eccentric shaft connection. S55 engine, structure of Valvetronic 44 BimmerFile.com S55 Engine 5. Valvetrain Index Explanation 1 Oil spray nozzle 2 Eccentric shaft 3 Torsion spring 4 Gate 5 Intake camshaft 6 Intermediate lever 7 Roller cam follower 8 Hydraulic valve adjuster 9 Valve spring 10 Intake valve 11 Valvetronic servomotor 12 Exhaust valve 13 Valve spring 14 Hydraulic valve adjuster 15 Roller cam follower 16 Exhaust camshaft 17 Sealing cup 18 Socket 45 BimmerFile.com S55 Engine 6. Belt Drive & Auxiliary Components 6.1. Belt drive The belt drive had to be modified due to the use of a mechanical coolant pump and deletion of the hydraulic power steering pump. An additional tensioning pulley is used between the vibration damper and the air conditioning compressor, which compensates for the deletion of the hydraulic power steering pump. The additional tensioning pulley suppresses possible oscillations of the drive belt between the vibration damper and air conditioning compressor. S55 engine, belt drive Index Explanation Belt pulley, alternator Additional tensioning pulley Drive belt Drive belt Mechanical belt tensioner Belt pulley, A/C compressor Deflecting element Vibration damper with double belt pulley Coolant pump belt pulley The diameter of the belt pulley for the alternator was increased in comparison to the one on the N55 engine. This was necessary as the alternator would generate excessive speeds due to the higher engine speeds of the S55 engine. With the addition of a mechanical coolant pump, a pulley and drive belt are added to the drive belt system, unlike the N55 which only has one drive belt. 46 BimmerFile.com S55 Engine 6. Belt Drive & Auxiliary Components 6.1.1. Vibration damper The S55 engine uses a single-mass vibration damper. The belt pulley for the auxiliary components sits behind the damper. The drive pulley for the coolant pump sits on the front side of the vibration damper. ® ® © S55 engine, vibration damper Index Explanation 1 Coolant pump belt pulley 2 Vibration damper 3 Belt pulley, auxiliary components 47 BimmerFile.com S55 Engine 7. Oil Supply 7.1. Oil circuit 7.1.1. Oil passages The following graphic provides an overview of the oil circuit of the S55 engine. S55 engine, oil passages (rearview) Index Explanation 1 Oil filter 2 Main oil passage (filtered oil) 3 VANOS unit, intake side 4 VANOS solenoid valve, intake side 5 VANOS unit, exhaust side 48 BimmerFile.com T014-0204 S55 Engine 7. Oil Supply Index Explanation 6 Oil passage for the intake camshaft lubrication and eccentric shaft lubrication 7 Oil passage for the exhaust camshaft lubrication 8 Hydraulic valve clearance compensation 9 VANOS solenoid valve, exhaust side 10 Chain tensioner 11 Oil pressure control valve 12 Exhaust turbocharger 13 Connection for the oil spray nozzles and connection for the exhaust turbocharger lubrication 14 Crankshaft bearings 15 Intake pipe 16 Suction pump 17 Oil pump 18 Oil passage for the oil-pressure control 19 Oil passage for the vacuum pump lubrication 20 Oil passage for the oil-pressure control 21 Vacuum pump 22 Unfiltered oil passage 49 BimmerFile.com S55 Engine 7. Oil Supply S55 engine, oil passages (front view) Index Explanation 1 Oil filter 2 Main oil passage (clean oil) 3 VANOS unit, intake side 4 VANOS solenoid valve, intake side 5 VANOS unit, exhaust side 6 Oil passage for the intake camshaft lubrication and eccentric shaft lubrication 8 Hydraulic valve clearance compensation 9 VANOS solenoid valve, exhaust side 10 Chain tensioner 11 Oil pressure control valve 12 Exhaust turbocharger 50 BimmerFile.com T014-0 S55 Engine 7. Oil Supply Index Explanation 13 Connection for the oil spray nozzles and connection for the exhaust turbocharger lubrication 14 Crankshaft bearings 15 Intake pipe 16 Suction pump 17 Oil pump 18 Oil passage for the oil-pressure control 19 Oil passage for the vacuum pump lubrication 20 Oil passage for the oil-pressure control 21 Vacuum pump 22 Raw oil passage 51 BimmerFile.com S55 Engine 7. Oil Supply 7.1.2. Oil return The following graphic shows the integrated oil deflector. The following components have been combined: • Oil deflector (5) • Intake snorkel (3) The integrated oil deflector gives rise to the largest possible cavity sealing between the oil pan and crankshaft drive. Additional oil scraper edges are fitted at the bedplate which direct oil spray from the crankshaft. The oil flowing back from the cylinder head is directed under the oil deflector. This way, even at high lateral acceleration, no returning oil can reach the crankshaft and cause churning losses. Index Explanation S55 engine, bedplate with oil pump, suction pump and oil deflector Oil pump 2 Bedplate 3 Intake pipe with oil strainer 4 Oil return passages, intake side 5 Oil deflector 6 Oil return passages, exhaust side 52 BimmerFile.com S55 Engine 7. Oil Supply S55 engine, oil return passages Index Explanation 1 Engine oil return, exhaust side 2 Cooling passage 5 Engine oil return, intake side 53 BimmerFile.com S55 Engine 7. Oil Supply 7.1.3. Oil pump and pressure control Passages were integrated for the oil supply of the vacuum pump, it is lubricated by filtered oil like in the N55 engine. Also, the oil pressure control valve was retained for the map-controlled oil pump, like the N55 engine. Index Explanation 1 Oil pressure control valve 2 Oil pump A modified version of the pendulum slide oil pump, known from the N55 engine, is used. The flow cross-sections within the oil pump have been optimized in the S55 engine for less loss; as a result, the delivery rate of the pump has improved by 18%. The shaft of the oil pump has an additional hexagon socket for the drive of the suction pump. The function of the oil pump can be found in the Technical Reference Manual "ST1209 N63TU Engine". The function of the pressure regulation is described in the Training Reference Manual "ST916 N55 Engine". 54 BimmerFile.com S55 Engine 7. Oil Supply S55 engine, oil pump Index Explanation 1 Control oil chamber 2 Pressure-limiting valve 3 Rotor 4 Vane 5 Pendulum slide 6 Inner rotor 7 Housing 8 Bore hole for pressure control valve 9 Damping oil chamber 10 Compression spring (2x) 11 Rotational axis The structure of the oil pump was revised in order to guarantee the function and durability of the pendulum slide made from thermosetting plastics. 7.1.4. Suction pump In order to adapt the oil supply to motor racing requirements, a second oil pump was installed as a backup. The second oil pump, also called a suction pump, supports the return flow of oil from the exhaust turbochargers and the front areas of the oil pan back to the rear of the oil pan. 55 BimmerFile.com S55 Engine 7. Oil Supply © S55 engine, oil pump connected to suction pump © ('j O Index Explanation A Oil pump unit with oil deflector and intake snorkel from below B Oil pump unit without oil deflector and intake snorkel from above 1 Oil pump 2 Link 3 Intake pipe, left, oil sump, front 4 Suction pump 5 Return flow 6 Oil deflector with intake pipe 7 Intake pipe, exhaust turbocharger, cylinders 4-6 8 Twin-flow intake pipe, oil sump, front right and exhaust turbocharger, cylinders 1-3 56 BimmerFile.com S55 Engine 7. Oil Supply With these changes the oil supply can be guaranteed up to a longitudinal acceleration of 0.61 g and down to -1.2 g in the case of deceleration. Also with lateral acceleration, for example during cornering, this oil supply system enables a secure oil supply up to a constant 1.2 g. © ® © ® S55 engine, engine oil level Index Explanation A Negative longitudinal acceleration (braking) B Lateral acceleration (dynamic cornering) 1 Engine oil level during braking and cornering 2 Oil pan With the intake pipes (2,4,8), the suction pump draws oil from the front of the oil pan during longitudinal acceleration and from the sides of the oil pan during lateral acceleration. The oil drawn in is delivered by the return flow (6) back to the rear part of the oil pan. There the oil pump can re-absorb the oil via the oil deflector with intake pipe (7) and deliver it to the engine lubrication points. The bearings of the exhaust turbochargers may collect engine oil due to the centrifugal force during lateral acceleration conditions. This prevents a normal backflow to the oil pan and thus a supply of fresh cool engine oil to the bearings. To counteract this effect, the bearings of the exhaust turbochargers have engine oil continuously drawn in by the suction pump and delivered to the oil pan. 57 BimmerFile.com S55 Engine 7. Oil Supply S55, oil suction, exhaust turbocharger Index Explanation 1 Oil pump 2 Intake pipe, left, oil sump, front 3 Link 4 Twin-flow intake pipe, oil sump, front right and exhaust turbocharger, cylinders 1-3 5 Suction pump 6 Return flow 7 Oil deflector with intake pipe 8 Intake pipe, exhaust turbocharger, cylinders 4-6 9 Oil return lines, exhaust turbocharger The suction pump is a twin-flow gear pump. The outer chambers of the gear pump serve as suction chambers. At the suction chambers the intake pipes are connected which consist of the oil return lines from the exhaust turbochargers and the intake pipes at the front oil pan. The inner chamber is a pressure chamber. The pressure chamber delivers the engine oil back to the rear of the oil pan via the return flow. Engine oil in the rear of the oil pan is thus available again to the oil pump via the intake pipe. 58 BimmerFile.com S55 Engine 7. Oil Supply S55 engine, suction pump Index Explanation A Suction pump, rear part B Suction pump, front part 1 Intake pipe, exhaust turbocharger, cylinders 4-6 2 Gear pump 3 Return flow 4 Intake pipe, left, oil sump, front 5 Twin-flow intake pipe, oil sump, front right and exhaust turbocharger, cylinders 1-3 59 BimmerFile.com S55 Engine 7. Oil Supply 7.1.5. Oil filter and engine oil cooling The oil filter housing is made from aluminium. For the engine oil cooling an upstream engine oil cooler is used which is installed in a horizontal position in front of the radiator package. Depending on the engine oil temperature, a thermostat at the oil filter housing enables the oil flow to the engine oil cooler. Due to the higher engine performance, a large heat quantity must be dissipated by the engine oil cooler. The opening range of the thermostat is therefore earlier than in the N55 engine. S55, engine oil cooling Index Explanation 1 Engine oil cooler 2 Engine oil pipe, return 3 Engine oil pipe, supply 4 Thermostat 5 Oil filter 60 BimmerFile.com S55 Engine 7. Oil Supply 7.1.6. Oil spray nozzles The S55 engine has oil spray nozzles for the piston crown cooling. They are common parts to the N55 engine. A special tool is required for the positioning of the oil spray nozzles. 7.1.7. Engine oil pressure monitoring Oil pressure Since the S55 engine has a electronic volume controlled oil pump, it is necessary to record the oil pressure precisely. This is why a new sensor (Puls2) is used. The advantages of the new sensor are: • Measurement of the absolute pressure (previous sensor measured relative pressure) • Characteristic map control possible at every engine speed. Oil level The familiar oil-level sensor is used for the oil level measurement. 61 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems 8.1. Air intake system 8.1.1. Overview For the S55 engine, the air intake system had to be completely revamped. The following are the components that were revamped: • Air intake duct up to the intake silencer • Clean air duct, due to new exhaust turbochargers, completely new • Crankcase venting components • Indirect charge air cooling • Recirculation air system deleted • Tank ventilation system adapted As can be seen from the graphic, the structure of the intake air system is more comprehensive, as two exhaust turbochargers are installed and indirect charge air cooling is used. S55 engine, intake air system 62 BimmerFile.com TO14-021 S55 Engine 8. Air Intake & Exhaust Emission Systems Index Explanation 1 Hot film air mass meter, cylinders 4-6 2 Charge air pipe, cylinders 1-3 3 Charge air pipe, cylinders 4-6 4 Intake plenum 5 Indirect charge air cooler 6 Throttle valve 7 Charge air pipe 8 Charge air pressure-temperature sensor 9 Lid, intake silencer, cylinders 1-3 10 Intake silencer, cylinders 1-3 11 Unfiltered air line, cylinders 1-3 12 Intake snorkel, cylinders 1-3 13 Hot film air mass meter, cylinders 1-3 14 Connection, crankcase ventilation 15 Exhaust turbocharger, cylinders 4-6 16 Exhaust turbocharger, cylinders 1-3 17 Intake snorkel, cylinders 4-6 18 Unfiltered air line, cylinders 4-6 19 Intake silencer, cylinders 4-6 20 Lid, intake silencer, cylinders 4-6 63 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems S55 engine, intake air system from above Index Explanation A Fresh air B Clean air C Heated charge air D Cooled charge air 1 Intake snorkel, cylinders 4-6 2 Unfiltered air line, cylinders 4-6 3 Intake silencer, cylinders 4-6 4 Lid, intake silencer, cylinders 4-6 5 Hot film air mass meter, cylinders 4-6 6 Charge air pipe, cylinders 1-3 7 Charge air pipe, cylinders 4-6 8 Indirect charge air cooler 64 BimmerFile.com T014-0216 S55 Engine 8. Air Intake & Exhaust Emission Systems Index Explanation 9 Charge air pressure-temperature sensor 10 Intake snorkel, cylinders 1-3 11 Unfiltered air line, cylinders 1-3 12 Intake silencer, cylinders 1-3 13 Lid, intake silencer, cylinders 1-3 14 Hot film air mass meter, cylinders 1-3 15 Connection, crankcase ventilation 16 Intake plenum 17 Exhaust turbocharger, cylinders 4-6 18 Exhaust turbocharger, cylinders 1-3 A blow-off valve is no longer required due to the modified engine control. Similar to the S63 top (S63TU) engine, the undesired spikes in charging pressure, which may arise in the event of quick throttle valve closure, are reduced . The electrical wastegate valves also play an important role in terms of the engine acoustics and contribute to the component protection of the turbochargers. 65 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems 8.1.2. Intake manifold The engine control unit is mounted to the intake manifold. Intake air is used to cool the engine control unit. With this arrangement, the engine comes down the production line completely assembled with the control unit, sensors, and actuators already connected. S55 engine, intake air system with DME control unit Index Explanation 1 Connecting flange for cooling the engine control unit 2 Connecting flange for the throttle valve 3 Intake manifold 4 Engine control unit 5 Cooling fins 66 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems 8.1.3. Tank ventilation system The S55 engine has a tank ventilation system that is similar to that of the N55 engine. Fuel vapors are stored in the charcoal canister and then fed via the tank vent valve to the combustion process. Index Explanation S55 engine, tank ventilation system Connection after throttle valve 2 Tank vent valve 3 Connection before throttle valve 4 Connection to the tank ventilation line from the carbon canister Connection before turbocharger 67 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems 8.2. Exhaust emission system 8.2.1. Overview The S55 engine has a different exhaust system structure than in the N55 engine. It uses two mono¬ scroll turbochargers instead of the single twin-scroll turbocharger of the N55. The exhaust system is a twin-pipe system in relation to the cylinder banks 1 and 2. In addition to the two catalytic converters (3/5) located close to the engine, two underbody catalytic converters (7/8) with a twin-pipe center silencer (9) and a rear silencer (10) are also installed. The exhaust system was designed for minimum exhaust back pressure. The gas exchange efficiency was further optimized by sport tuning and intelligent lightweight construction. The weight was able to be reduced through selective wall thickness reduction. S55 engine, exhaust system Index Explanation 1 Exhaust manifold, cylinders 1-3 2 Exhaust manifold, cylinders 4-6 3 Catalytic converter, cylinders 4-6 4 Exhaust turbocharger, cylinders 4-6 5 Catalytic converter, cylinders 1-3 6 Exhaust turbocharger, cylinders 1-3 7 Underbody catalytic converters, cylinders 4-6 68 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems Index Explanation 8 Underbody catalytic converters, cylinders 1 -3 9 Center silencer 10 Rear silencer 11 Exhaust tailpipes The rear silencer has the typical M chrome-plated 4 exhaust tailpipes. The pneumatic exhaust flaps were replaced, in the S55 engine, with electrical exhaust flaps. This simplifies the vacuum system and the vacuum reservoir in the cylinder head cover could therefore be deleted. The electrical exhaust flaps are activated directly by the DME by a pulse-width modulated signal. Index Explanation 1 Bypass pipe, left 2 Bypass pipe, right 3 Electrical exhaust flap actuator (EAKS), right 4 Rear silencer 5 Twin tailpipe 6 Electrical exhaust flap actuator (EAKS), left 69 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems The exhaust flap can be opened by a pulse-width modulated (PWM) signal of 10% and closed with a signal of 90% . The end positions are the mechanical limit positions of the exhaust flap. Intermediate settings are not intended. The exhaust flap can be moved to the service position for installation by a PWM signal of 50%. To guarantee the desired position, in the case of extended non-operation of the electrical exhaust flap actuator, every 320 s (+/-10%) a current is applied, which works in the direction of the limit position (duration of current feed: 50 ms +/- 5 ms). Functional input variables for the calculation of the exhaust flap setting are: • Vehicle speed • Accelerator pedal angle • Engine temperature • Transmission version • Gear mode There is always a flow through the two tailpipe pairs by the bypass pipe (1+2) regardless of the flap position. Therefore, no varying blackening of the two tailpipe pairs occurs, which is typical of vehicles with exhaust flaps. Furthermore, the exhaust flaps are not visible at the tailpipes. Together with the Active Sound Design (ASD) and the electrical exhaust flaps, an optimal sound setting can be generated in every operating condition of the S55 engine, in the new M3/M4 Coupe. This results in a dominant, recognizable sound typical of BMW M vehicles. The character of the sound can vary depending on what mode the driver selects via the engine dynamics button. The three modes of the engine dynamics are Normal, Sport, and Sport+. 8.2.2. Exhaust manifold The exhaust manifold is made from high-alloyed cast steel. One exhaust manifold is used for each bank, similar to the N54 engine. The condensing of the three exhaust ducts into a single exhaust duct results in an optimal flow to the turbine of the turbocharger. The exhaust manifold and turbine housing of the turbocharger are cast together, forming one component/unit. S55 engine, connection of exhaust turbochargers at the engine housing 70 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems Index Explanation 1 Exhaust manifold, cylinders 4-6 2 Connection for the charge air cooler, cylinders 4-6 3 Exhaust manifold, cylinders 1-3 4 Connection for the charge air cooler, cylinders 1 -3 5 Electrical wastegate valve actuator, cylinders 1-3 6 Oil return 7 Coolant connections 8 Wastegate valve, control rod, cylinders 1-3 9 Connection for the exhaust system 10 Electrical wastegate valve actuator, cylinders 4-6 11 Oil return 12 Coolant connections 13 Wastegate valve, control rod, cylinders 4-6 14 Connection for the exhaust system 71 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems 8.2.3. Lightweight construction of heat shields for exhaust manifold New weight-optimized heat shields are used in order to guarantee heat insulation, of the new cast steel manifold, and to support the intelligent lightweight construction concept of the S55 engine. S55, lightweight construction heat shields Index Explanation 1 Heat shield, exhaust turbocharger, cylinders 4-6 2 Heat shield, support 3 Heat shield, exhaust turbocharger, cylinders 1-3 4 Heat shield, engine oil pipe The heat shields are made from aluminum (AIMg3). A weight savings of 1,450 grams (3.2lbs) is achieved compared to the same heat shields made from sheet steel, which is used on standard engines. 72 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems 8.2.4. Exhaust turbocharger The S55 engine has two mono-scroll exhaust turbochargers, like the N54 engine. Even though there are two turbocharger units, this design still contributes to the intelligent lightweight construction of the S55 engine. The weight of the two mono-scroll turbochargers in the S55 engine was able to be retained at the weight of the one twin-scroll turbocharger in the N55 engine. For comparison: The twin-scroll turbocharger unit in the N55 weighs 14.1 kg (31.1 lbs), the mono-scroll turbocharger units in the S55 engine weigh 14.2 kg (31.3 lbs). S55 engine, mono-scroll turbocharger unit, front view (bank 1/cyl 1-3) Index Explanation 1 Exhaust ports bank 1 (cylinders 1-3) 2 Output for charge air cooler 3 Electrical wastegate valve actuator 4 Input, clean air 5 Oil return 6 Coolant connections 7 Wastegate valve control rod 8 Connection for the exhaust system 73 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems S55 engine, mono-scroll turbocharger unit, rearview (bank 1/cyl 1-3) Index Explanation 1 Electrical wastegate valve actuator 2 Output for charge air cooler 3 Exhaust ports bank 1 (cylinders 1-3) 4 Connection for the exhaust system 5 Oil supply 6 Input, clean air Electrical wastegate valve The S55 engine is equipped with electrical wastegate valves, unlike the N54 which has the pneumatic design. The function of the electrical wastegate valves in the S55 engine is the same as in other BMW engines equipped with these valves. One important function is to satisfy ULEV2 emission standards. The main advantages of the electrical wastegate valve compared to the pneumatic wastegate valve are: • High adjustment speed • Precise boost pressure control • High closing force, thus less leakage and quicker build-up of boost pressure • Complete opening of the wastegate valve possible (This supports quick heating of catalytic converter upon cold start) • Lower exhaust emissions • Fuel economy The electrical wastegate valve is activated directly via the DME by a pulse-width modulated signal. 74 BimmerFile.com S55 Engine 8. Air Intake & Exhaust Emission Systems 8.2.5. Catalytic converter The S55 engine has two catalytic converters per bank. One main catalytic converter is installed close to the engine of each bank. The secondary catalytic converter is located in the underbody area after the transmission. Index Explanation 1 Oxygen sensor before the main catalytic converter, cylinders 1-3 2 Main catalytic converter, cylinders 1-3 3 Oxygen sensor after the main catalytic converter, cylinders 1-3 4 Oxygen sensor before the main catalytic converter, cylinders 4-6 5 Main catalytic converter, cylinders 4-6 6 Oxygen sensor after the main catalytic converter, cylinders 4-6 7 Secondary catalytic converter, cylinders 4-6 8 Secondary catalytic converter, cylinders 1 -3 75 BimmerFile.com S55 Engine 9. Vacuum System 9.1. Design The S55 engine is equipped with a vacuum pump for generating the vacuum required by the brake booster. © Index Explanation 1 Vacuum pump 2 Non-return valve 3 Non-return valve 4 Brake booster 76 BimmerFile.com S55 Engine 9. Vacuum System 9.1.1. Vacuum pump The vacuum pump is similar to the one used in the N55 engine. However, unlike the vacuum pump in the N55 engine, it is designed as a single-stage pump and only has one connection. The one connection is for the brake booster. Index Explanation 1 Connection opening for the brake booster 2 Non-return valve for the brake booster 3 Housing of the vacuum pump 4 Vane A vacuum reservoir was deleted as all pneumatic functions which were supplied via vacuum on the N55 engine have been electrified on the S55 engine. For example, the wastegate valves and exhaust flaps are now electrical on the S55 engine. 77 BimmerFile.com S55 Engine 10. Fuel System 10.1. Overview The S55 engine uses the high-pressure fuel injection system (HDE), similar to the N55 engine. Instead of the high precision injectors (HPI) known from the N54 and N63 engines, solenoid valve fuel injectors with multi-hole nozzles are used in the S55 engine. The following overview shows the entire fuel injection system. The fuel preparation of the S55 engine is closely related to the fuel preparation of the N55 engine. In the S55 engine, a new double¬ piston high pressure fuel pump is used, whereas the N55 engine has a single-piston high pressure pump. This is necessary in order to provide for the higher fuel demand needed with the increased performance and engine speeds of the S55 engine. The high pressure fuel injection valves meet the exhaust emission standards ULEV2. The S55 uses high pressure fuel injection valves from Bosch with the designation HDEV5.2, which also support the Controlled Valve Operation (CVO) function. S55 engine, high-pressure fuel injection system Index Explanation 1 High pressure line, high pressure pump 2 2 High pressure line, high pressure pump 1 3 High pressure line for injectors 4 Solenoid valve fuel injector 5 Rail pressure sensor 6 Rail 7 Fuel feed line 78 BimmerFile.com S55 Engine 10. Fuel System Index Explanation 8 Quantity control valve, high pressure pump 2 9 Fuel pressure sensor 10 High pressure pump element 2 11 Position sensor 12 Vacuum pump 13 High pressure pump element 1 10.1.1. Low pressure fuel sensor The fuel is supplied to the high pressure fuel pumps by the in tank electric fuel pump through a feed line at a primary pressure of 5 bar. The primary pressure is monitored via the low pressure fuel sensor. This low pressure fuel sensor is known from the N55, N54, and N63 engines. In the event of a failed low pressure fuel sensor, the electric fuel pump continues to operate at 100% delivery rate with terminal 15 ON. S55 engine, high pressure pump assembly Index Explanation 1 Vacuum pump 2 Non-return valve, brake servo 3 Connection for high pressure line, high pressure pump 1 4 Quantity control valve, high pressure pump 1 5 Connection for high pressure line, high pressure pump 2 79 BimmerFile.com S55 Engine 10. Fuel System Index Explanation 6 Fuel delivery line 7 Quantity control valve, high pressure pump 2 8 Low pressure fuel sensor 9 Position sensor 10.1.2. High pressure fuel pumps The high pressure fuel pumps, known from the N20 and N63 engines, are bolted into the vacuum pump housing. The vacuum pump drive shaft runs the entire length of the vacuum pump housing and acts as a camshaft with two three-point lobes (triple lobes) to drive the high pressure fuel pumps. Each point of the three-point lobes is offset by 120° degrees. The two three-point lobes, which drive the two high pressure pumps, are arranged so that there is a delivery every 60° degrees. The high pressure fuel pump, HDP 5, is used and has the same function as the high pressure pump in the N55 engine. However, for the S55 engine, two high pressure pumps are installed in parallel and the fuel lines are arranged differently. Below approx. 3,000 rpm only one high pressure pump is activated, at engine speeds above approx. 3,000 rpm both high pressure pumps are active. This was necessary in order to satisfy the higher volume of fuel needed at high engine speeds and loads. Regulation is carried out by the quantity control valve of the second high pressure pump. The quantity control valves, of the high pressure pumps, are controlled by a pulse-width-modulated signal from the DME. S55 engine, vacuum pump with high pressure pump elements 80 BimmerFile.com S55 Engine 10. Fuel System Index Explanation A Vacuum pump with high pressure pump drive B Pump elements 1 Non-return valve for the brake servo 2 Connections, high pressure pump element 3 Position sensor 4 Vacuum pump with drive for high pressure pump element 5 Drive 6 Fuel feed 7 Fuel quantity control valve 8 Mounting plate 9 Pump tappet 10 Connection, high pressure line An additional sensor detects the position of the camshaft that drives the high pressure fuel pumps. The position of the camshaft in the high pressure pump is required in order to optimize the pump control by the quantity control valves. The position sensor works according to the hall effect principle. It tracks the sensor gear electronically and sends the signal to the DME which in turn activates the quantity control valves for the fuel quantity control. The double three-point lobe camshaft is permanently driven by the vacuum pump. The fuel is pressurized by the high pressure fuel pumps and delivered to the fuel rail via the two high pressure lines. The fuel stored under pressure in the fuel rail is distributed via the high pressure lines to the high-pressure fuel injection valves. The required fuel pressure is determined by the DME according to the engine load and speed. The fuel pressure is registered by the rail pressure sensor and sent to the DME. The fuel is regulated by the quantity control valve, on high pressure pump 2, based on a target/ actual value comparison of the rail pressure. The fuel pressure is adjusted to achieve smooth running properties with the best possible fuel consumption. The maximum pressure of 200 bar is only required at a high load and low speed. 81 BimmerFile.com S55 Engine 10. Fuel System Index Explanation m Load n Engine speed P Pressure ACHTUNG! Offnen d«i KraftslofHy«Umt Mi KuhlmilMMmpcratur uMf <0 C nett lulaug G«*«tt von KoeporvonaUung R«p*r»ur»rt*«imQ Macttan CAUTION I Do not open tho fuel jyrtem rf im cooUnt temperature* above 40 'C/104 F - n*k of mfjry' Conujtt He rape* manual ATTENTION I II nl vyerot tfouvnr la sy«eme tfaumentaoon an carburant longue la temperature du Irqiade de retrordistement est iupanaure a 40 C Risque de bfesaure Respecter las instructions du Manuel de reparation IATENCION' Prottbido abnr el sistema da combustible cuando la lemperatura del liqudo rofngerante supare to* 40 C Pebgro de lesionas Consutar N manual de reparaoones 3* I iWSftSgaTeOUKlIimitnJfiK**^. »74i7 Warning for working on the high-pressure fuel system 10.1.3. Fuel Injectors The Bosch HDEV5.2 solenoid valve fuel injectors are used in the S55, like in the N20 and N55 engines. The solenoid valve fuel injectors are designed as inward-opening multi-hole valves with highly variable spay angle and spray pattern. They are designed for system pressure of up to 200 bar. The high-pressure fuel injection valves help satisfy ULEV2 emission standards. The high-pressure fuel injection valves have different diameters of the laser-manufactured bore holes in the nozzles. The fuel quantity of the two spray jets in the exhaust direction is reduced by 20%, which increases the other spray jets by 10% respectively. 82 BimmerFile.com S55 Engine 10. Fuel System Index Explanation 1 High-pressure connection 2 Electrical connection 3 Six-hole nozzle 4 ULEV1, injection pattern 5 ULEV2, injection pattern 83 BimmerFile.com S55 Engine 10. Fuel System High-pressure fuel injection valves with solenoid coils do not have a linear behavior pattern across the entire service life, mainly in the area of minimal quantity fuel injection. This means over time the fuel injection rates vary from one injector to another injector. The high-pressure fuel injection valves are adapted during start-up by the injection quantity compensation in the DME, in order to compensate possible manufacturing tolerances and adjust all injectors to each other. However, this only happens once during start-up (injection quantity compensation). The parameters for the activation of the injectors such as current and activation duration are the same for all injectors during the entire operating time and cannot be individually adapted. During the operating time, this would lead to transgressions from the strict exhaust gas emissions legislation such as ULEV2. - ® - © -® Index Explanation A Injector adaptation, start-up B Injector distribution during the operating time 1 Injector, cylinder 1 2 Injector, cylinder 2 3 Injector, cylinder 3 4 Injector, cylinder 4 5 Injector, cylinder 5 6 Injector, cylinder 6 The injectors are now therefore adjusted over the operating time with the help of a software function called "Controlled Valve Operation" (CVO) in the DME. The aim here is to limit the deviation of the individual injectors to each other to +/-10%. 84 BimmerFile.com S55 Engine 10. Fuel System - © - © -© S55 engine, injector, minimal quantity adjustment with CVO Index Explanation A Injector adaptation, start-up B Injector distribution during the operating time 1 Injector, cylinder 1 2 Injector, cylinder 2 3 Injector, cylinder 3 4 Injector, cylinder 4 5 Injector, cylinder 5 6 Injector, cylinder 6 The basic principle of the CVO function is to determine the precise opening period of the high pressure fuel injection valves. The DME can determine the precise opening period using the following parameters: • Power consumption of the high-pressure fuel injection valve • Voltage at the high-pressure fuel injection valve These current and voltage values change in the event of a needle movement in the high-pressure fuel injection valve, for example: • Armature mists up - when the needle valve is withdrawn from the valve seat • Armature moves - needle valve moves in direction of open position • Armature is stationary - attachment of needle valve at fully open position • Reverse movement • Armature moves - needle valve moves in direction of closed position • Armature suffers impact and is braked hydraulically - needle valve closed 85 BimmerFile.com S55 Engine 10. Fuel System With these values, the DME can determine the actual opening period of the high-pressure fuel injection valve. If the precise opening periods are known, the DME can also determine the exact fuel injection rate. If the fuel injection rates vary, then the DME can control the fuel injection rate by the opening period of each individual injector valve. The DME thus has the option to adjust all high-pressure fuel injection valves to the same nominal fuel injection rate. This measure guarantees the same nominal fuel injection rate in all cylinders, primarily in the minimal quantity range, as well as at idle speed, so that the exhaust recirculation can always work efficiently. This is reflected in the emissions values and compliance with the existing exhaust emission standards ULEV2. A_ Work on the fuel system is only permitted after the engine has cooled down. The coolant temperature must not exceed 40 °C. This measure must be observed without fail, as otherwise there is a risk of fuel being sprayed back on account of the residual pressure in the high-pressure fuel system. When working on the high-pressure fuel system, it is essential to adhere to conditions of absolute cleanliness and to observe the work sequences described in the repair instructions. Even the slightest contamination and/or damage to the screwed fittings of the high-pressure lines can cause leaks. When working on the fuel system of the S55 engine, it is important to ensure that the ignition coils are not fouled with fuel. The resistance of the silicone material is greatly reduced by having contact with fuel. This may result in arching on the spark plug head and thus in misfires. • Before making any modifications to the fuel system, make sure to remove the ignition coils and protect the spark plug holes against of fuel ingress by covering with them with a rag. • Before reinstalling the solenoid valve injectors, remove the ignition coils and ensure the best cleanliness conditions are maintained. • Ignition coils heavily fouled by fuel must be replaced. • The CVO function comprise the system components "Injector" and "Digital Engine Electronics" (DME). These components therefore have to be identified with the vehicle identification number in the EPC in the event of a replacement. • For injectors and a DME which supports the CVO function, the injection quantity compensation during the replacement of one of the components is deleted. • The information and repair instructions in the Integrated Service Technical Application (ISTA) must be observed. 86 BimmerFile.com S55 Engine 11. Cooling System 11.1. Overview The S55 engine cooling system consists of engine and charge air cooling, as well as oil cooling for the engine oil and the M DCT. S55 engine, cooling system Index Explanation 1 Upstream low-temperature radiator, charge air 2 Radiator, engine 3 Low-temperature radiator, charge air 4 Indirect charge air cooler 5 Coolant expansion tank, charge air 6 Coolant expansion tank, engine 87 BimmerFile.com 314-0234 S55 Engine 11. Cooling System Index Explanation 7 Thermostat, transmission oil cooling, M DCT 8 Upstream radiator, engine 9 Engine oil cooler 10 M DCT transmission oil cooler S55 engine, engine cooling with exhaust turbochargers and charge air cooling 88 BimmerFile.com S55 Engine 11. Cooling System Index Explanation 1 Low-temperature radiator, charge air 2 Upstream low-temperature radiator, charge air 3 Radiator, engine 4 Electric coolant pump, low-temperature circuit, charge air 5 Coolant expansion tank, charge air 6 Thermostat 7 Mechanical coolant pump, engine 8 Electric coolant pump for turbochargers 9 Turbochargers 10 Heat exchanger 11 Electric coolant pump, heating for passenger compartment 12 Coolant temperature sensor 13 Indirect charge air cooler 14 Coolant expansion tank, engine 15 Electric fan 16 Upstream radiator, engine 89 BimmerFile.com S55 Engine 11. Cooling System 11.2. Engine cooling Index Explanation 3 Radiator, engine 6 Thermostat 7 Mechanical coolant pump, engine 8 Electric coolant pump for turbochargers 9 Turbochargers 10 Heat exchanger 11 Electric coolant pump, heating for passenger compartment 90 BimmerFile.com T014-0236 S55 Engine 11. Cooling System Index Explanation 12 Coolant temperature sensor 14 Coolant expansion tank, engine 15 Electric fan 16 Upstream radiator, engine The following graphic shows the connection of an auxiliary radiator to the cooling system. The auxiliary radiator is connected in parallel to the radiator with coolant lines, thus increasing the cooling surface area. S55 engine, coolant circuit with exhaust turbochargers Index Explanation 1 Auxiliary radiator, engine 2 Radiator, engine 3 Coolant expansion tank, engine 4 Mechanical coolant pump, engine 5 Thermostat 6 Turbocharger unit 7 Heat exchanger 8 Electric coolant pump for turbochargers 9 Electric coolant pump, heating for passenger compartment 91 BimmerFile.com S55 Engine 11. Cooling System The S55 engine uses a conventional belt driven coolant pump which replaces the electric coolant pump known from the N54 and N55 engines. 11.2.1. Coolant passages The coolant passages in the cylinder head are also used for indirect cooling of the fuel injectors. The following graphic shows that the coolant flows around the valves and fuel injectors. The heat transfer to these components is therefore reduced to a minimum. S55 engine, coolant passages in the cylinder head Index Explanation 1 Passage, intake valves 2 Passage, injector 3 Passage, exhaust valves 4 Connection of coolant hose and thermostat (small cooling circuit) 5 Connection of coolant hose and radiator (large cooling circuit) 92 BimmerFile.com S55 Engine 11. Cooling System 11.2.2. Cooling circuit, exhaust turbochargers © ® <*>-=© ► 1 ■ 1 4m i4m 1 1 -— S55 engine, cooling circuit of the turbochargers with electrical auxiliary coolant pump 9 b Index Explanation 8 Electric coolant pump for the turbochargers 9 Turbochargers The conventional coolant pump is driven via the drive belt and cannot be used for cooling the turbochargers after the engine has shut down. This is why an auxiliary 20W electric coolant pump is used for the turbocharger coolant circuit. 93 BimmerFile.com S55 Engine 11. Cooling System Not only does this additional coolant pump operate after engine shut down, but also during engine operation taking into account the following factors: • Coolant temperature at the engine outlet • Engine oil temperature • Injected fuel quantity Using these values, the heat input to the engine is calculated. The after-run of the electric coolant pump can last up to 30 minutes. To improve the cooling effect, the electric fan is activated and can run for up to a maximum of 11 minutes after engine shut down. 94 BimmerFile.com S55 Engine 11. Cooling System 11.3. Charge air cooling In the S55 engine, like in the S63 engine, indirect charge air cooling is used. During the indirect charge air cooling, the charge air is cooled by a low-temperature cooling circuit. The low-temperature cooling circuit is then cooled via two radiators by ambient air. S55 Charge air cooling @ 9 o 1 — Index Explanation 1 Low-temperature radiator, charge air 2 Upstream low-temperature radiator, charge air 4 Electric coolant pump, low-temperature circuit, charge air 5 Coolant expansion tank, charge air 13 Indirect charge air cooler 95 BimmerFile.com S55 Engine 11. Cooling System Components The capacity of the charge air cooling circuit is approximately 4 liters. The circulation of the coolant in the charge air cooling circuit is accomplished by an 80W electric coolant pump. The two radiators are connected in parallel and are supplied via an expansion tank secured at the charge air cooler. The indirect charge air cooler has a cooling power of 36 kW (10.3RT- refrigeration tons). S55 engine, cooling circuit, charge air Index Explanation 1 Indirect charge air cooler 2 Coolant expansion tank, charge air 3 Low-temperature radiator, charge air 4 Electric coolant pump, low-temperature circuit, charge air 5 Upstream low-temperature radiator, charge air 96 BimmerFile.com S55 Engine 12. Engine Electrical System 12.1. Electrical system connection 12.1.1. Overview Like in the N55, the DME is bolted to the intake manifold and is cooled by the intake air. The advantages of the DME close to the engine are as follows: • The engine wiring harness is divided into six individual modules • All electrical components on the engine are supplied directly by the DME • E-box no longer needed • 211 pins are available, the connections are waterproof when connected • Shorter engine wiring harness • Simplification of the production BimmerFile.com S55 Engine 12. Engine Electrical System 12.1.2. System wiring diagrams System wiring diagram for MEVD17.2.G S55 engine, system wiring diagram for MEVD17.2.G BimmerFile.com T014-0206 S55 Engine 12. Engine Electrical System Index Explanation 1 DME, Valvetronic, direct fuel injection MEVD17.2.G 2 Temperature sensor 3 Ambient pressure sensor 4 Starter motor 5 Brake light switch 6 Front Electronic Module (FEM) 7 Air conditioning compressor 8 Refrigerant pressure sensor 9 Electronic fuel pump control 10 Electric fuel pump 11 Clutch module 12 Relay, terminal 15N 13 Relay, Valvetronic 14 Relay, ignition and fuel injection 15 Diagnostic module for tank leaks (DMTL) 16 Relay, terminal 30B 17 Relay for electric fan 18 Electric fan 19 Map thermostat 20 Electric coolant pump, exhaust turbocharger 21 Electric coolant pump, charge air cooling 22 Tank vent valve 23 VANOS solenoid valve, intake camshaft 24 VANOS solenoid valve, exhaust camshaft 25 Oil pressure control valve 26 Quantity control valve, high pressure pump 1 27 Quantity control valve, high pressure pump 2 28 Electrical exhaust flap, cylinders 1-3 29 Electrical exhaust flap, cylinders 4-6 30-35 Fuel Injectors 36-41 Ignition coils 42 Engine ventilation heating 43 Ground connections 44 Electrical wastegate valve actuator, cylinders 1-3 45 Electrical wastegate valve actuator, cylinders 4-6 99 BimmerFile.com S55 Engine 12. Engine Electrical System Index Explanation 46 Oxygen sensor after catalytic converter, cylinders 1-3 47 Oxygen sensor after catalytic converter, cylinders 4-6 48 Oxygen sensor before catalytic converter, cylinders 1-3 49 Oxygen sensor before catalytic converter, cylinders 4-6 50 Diagnostic socket 51 Fuel low-pressure sensor 52 Intake-manifold pressure sensor after throttle valve 53 Rail pressure sensor 54 Charge air temperature and pressure sensor 55 Knock sensor, cylinders 1-3 56 Hot film air mass meter, cylinders 1-3 57 Knock sensor, cylinders 4-6 58 Hot film air mass meter, cylinders 4-6 59 Gear sensor 60 Position sensor, high pressure pump 61 Camshaft sensor, intake camshaft 62 Camshaft sensor, exhaust camshaft 63 Crankshaft sensor 64 Accelerator pedal module 65 Electromotive throttle controller 66 Coolant temperature sensor 67 Oil pressure sensor 68 Oil temperature sensor 69 Valvetronic servomotor 70 Engine dynamics button 71 Oil level sensor 72 Alternator 73 Battery supervision circuits (BUE) 74 Dynamic Stability Control (DSC) 75 Integrated Chassis Management (ICM) 100 BimmerFile.com S55 Engine 12. Engine Electrical System 12.1.3. Engine control unit The S55 engine receives the engine control MEVD17.2.G from Bosch. The DME is integrated into the intake manifold and is cooled by the intake air. The MEVD17.2.G DME can operate on the FlexRay and supplies the sensors and actuators directly with voltage. The top side of the DME housing is also the lower section of the intake manifold. The DME housing is contoured in order to ensure optimal flow in the intake manifold. When connected, the plug connections between the wiring harness and DME are waterproof. 12.2. Functions 12.2.1. Fuel supply A voltage signal is sent from the low pressure fuel sensor to the DME based on the system pressure applied between the electric fuel pump and the high pressure pump. The system pressure (fuel pressure) is determined using the low-pressure fuel sensor before the high pressure pump. In the DME, a constant comparison of the nominal pressure and the actual pressure is carried out. In the event of a deviation of the nominal pressure from the actual pressure, the engine control unit increases or reduces the voltage for the electric fuel pump, which is sent as a message via the PT-CAN to the electric fuel pump control unit (EKP). The electric fuel pump control unit transforms the message into output voltage for the electric fuel pump. The necessary delivery pressure for the engine (or the high pressure pumps) is adjusted. In the event of a signal failure (low pressure fuel sensor) the electric fuel pump is pre-controlled with terminal 15 ON. If the CAN bus fails, the electric fuel pump is operated via the electric fuel pump control unit with the system voltage. The high pressure pumps increase the fuel pressure between 50 to 200 bar. The fuel reaches the rail via the high pressure lines. The fuel is stored temporarily in the rail and distributed to the fuel injectors. Fuel quantity control The rail pressure sensor measures the current fuel pressure in the rail. The excess fuel is returned to the inlets of the high pressure pumps when the quantity control valves are open. In the event of a failure of a high pressure pump, restricted driving is possible. The quantity control valves control the fuel pressure in the rail. The quantity control valves are activated by the engine control with a pulse-width-modulated signal. Depending on the pulse width, a variable throttle cross section is released, thus providing the quantity of fuel required for the current load status of the engine There is also an option to reduce the pressure in the rail. 12.2.2. Charging pressure control The charging pressure is controlled by the engine control via the wastegate valves at each of the two turbochargers. In order to be able to infinitely adjust the wastegate valves, electrical wastegate valves are installed which implement the signals from the engine control to open or close the wastegate valve. 101 BimmerFile.com S55 Engine 12. Engine Electrical System 12.3. Sensors 12.3.1. Crankshaft sensor The integrated crankshaft sensor has the same function as the crankshaft sensors used for the automatic engine start-stop function (MSA). The reverse detection of the engine is necessary for the MSA function. The sensor and the function are described in the Technical Reference Manual "ST 1112 Automatic Start Stop (MSA)". S55 engine, installation location of crankshaft sensor (using the example of the N55) Index Explanation A Line of vision on the crankshaft B Same line of vision without starter motor 1 Connector 2 Dust seal 3 Sensor 4 Multi-pole sensor gear 5 Starter 102 BimmerFile.com S55 Engine 12. Engine Electrical System S55 engine, crankshaft sensor with multi-pole sensor gear Index Explanation 1 Connector 2 Dust seal 3 Sensor 12.3.2. Ignition coil and spark plug Ignition coil The S55 engine uses the same ignition coils that are installed in the N55 engine. Like in the N55 engine, the ignition coils offer higher ignition voltage, better electromagnetic compatibility and improved strength. Spark plug The spark plugs of the S55 engine are M-specific components. 103 BimmerFile.com S55 Engine 12. Engine Electrical System 12.3.3. Oil pressure sensor The oil pressure sensor can determine the absolute pressure, which is necessary for more precise oil- pressure control. The sensor is identical in its structure to the low pressure fuel sensor. The oil pressure sensor is supplied with 5 V voltage by the DME. S55 engine, oil pressure sensor 12.3.4. Oxygen sensors S55 engine, catalytic converter Index Explanation 1 Oxygen sensor before catalytic converter 2 Connection at the exhaust turbocharger 3 Metal honeycomb structure 4 Catalytic converter housing 5 Oxygen sensor after catalytic converter The same connectors are used for the oxygen sensors as in the N55 engine. This connector system offers significantly better contact properties and reduces the "ambient noise" due to contact problems. Another improvement is the oscillation- and vibration-free contact point. 104 BimmerFile.com S55 Engine 12. Engine Electrical System Oxygen sensor before catalytic converter The oxygen sensors (LSU ADV) from Bosch are used as control sensors before the catalytic converters. The function is comparable to the oxygen sensor (LSU 4.9) and therefore is not described in detail here. This oxygen sensor is already used in the N55 and N63 engine. The abbreviation LSU stands for universal oxygen sensor and ADV for “Advanced”. The oxygen sensor before catalytic converter (LSU ADV) offers the following advantages: • High signal stability, especially in boost operation due to lower dynamic pressure dependence • Increased durability thanks to reduced pump voltage • Increased accuracy • Quicker operating readiness (< 5 seconds) • Greater temperature compatibility • Improved connector with better contact properties The LSU ADV has an extended measuring range, making it possible to measure precisely from lamda 0.65. The oxygen sensor is operational earlier, so after 5 seconds precise measurement values are available. The higher measuring dynamics of the sensor makes it possible to more effectively determine and control the fuel-air ratio of each cylinder. As a result, a homogeneous exhaust flow can be adjusted, the emission levels lowered and the long-term emission behavior optimized. Oxygen sensor after catalytic converter The oxygen sensor after catalytic converter is also called a monitoring sensor. The monitoring sensor LSF XFOUR from Bosch is used. The LSF XFOUR needs the MEVD17.2.G for the signal evaluation and is characterized by the following properties: • Quicker response characteristics after engine start (a more controlled heater was integrated in the LSF XFOUR) • Improved signal stability • Small installation space • High temperature resistance and optimal thermal shock protection • Resistance against condensation in the exhaust duct after a cold start is improved 105 BimmerFile.com S55 Engine 12. Engine Electrical System 12.3.5. Hot film air mass meter The hot film air mass meter 7 is used, like in the N55 engine. The S55 engine uses two hot film air mass meters, one for each bank. The hot film air mass meter measures the flow of the filtered air which is drawn in by the engine. In conjunction with other sensors, the quantity of the fuel to be injected is controlled. The HFM signal is also used in other system diagnosis, like fuel tank ventilation. In contrast to the hot film air mass meter in the N20 and N26 engine, the hot film air mass meter in the N55 and S55 engine has an independent temperature sensor. Index Explanation 1 Electrical connection 2 Sensor 12.4. Actuators 12.4.1. Valvetronic servomotor The brushless direct current motor, Valvetromic servomotor, is maintenance free and very powerful due to the contactless energy transfer. With the use of integrated electronic modules, it is controlled with precision. Function The activation of the Valvetronic servomotor is limited to a maximum of 40 A. Over a period of >200 milliseconds a maximum of 20 A is available. The Valvetronic servomotor is activated by a pulse-width- modulated signal. The duty cycle is between 5% and 98%. 106 BimmerFile.com S55 Engine 12. Engine Electrical System S55 engine, Valvetronic servomotor Index Explanation 1 Socket 2 Worm shaft 3 Needle bearing 4 Bearing cap 5 Magnetic gear sensor 6 Rotor with four magnets 7 Sensor 8 Stator 9 Housing 10 Bearings 107 BimmerFile.com S55 Engine 12. Engine Electrical System The sensor is supplied with 5 V voltage by the DME. The DME receives signals via five hall effect elements and evaluates them. Of the five hall effect sensors three are for rough classification and two are for precise classification. The angle of rotation of the servomotor can be determined at <7.5°. With the ratio of the worm drive, a very precise and quick lift adjustment of the valves is possible. 12.4.2. High-pressure fuel injection valve In the S55 engine the HDEV5.2 is based on the high-pressure fuel injection valve used in the N55 engine (HDEV5.2). The function is the same. Function The activation of the HDEV5.2 is effected in four phases, as shown in the following graphic: 108 BimmerFile.com S55 Engine 12. Engine Electrical System 109 BimmerFile.com TO08-2216 S55 Engine 12. Engine Electrical System Index Explanation A Activation signal, DME B Current flow HDEV5.2 C Voltage at HDEV5.2 1 Booster phase 2 Activation phase 3 Holding phase 4 Shutdown phase 1 Booster phase: In the Booster phase the opening of the HDEV5.2 is introduced by the DME with a high booster voltage. The Booster phase is completed when approx. 10 A is reached. The high current is achieved with a voltage of up to approx. 65 V. 2 Activation phase: In the activation phase the HDEV5.2 is opened fully after the booster phase by current control of around 6.2 A. At the end of the activation phase the current is reduced from the activation to the holding current level of approx. 2.5 A. 3 Holding phase: In the holding phase the applied HDEV5.2 is held open by current control of around 2.5 A. 4 Shutdown phase: The current is shut down in the shutdown phase after the end of the injection period. At least 2 milliseconds pass between two injection processes. 110 BimmerFile.com S55 Engine 13. Service Information 13.1. Engine mechanics 13.1.1. Engine housing Cylinder head A_ The combination of exhaust turbocharger, Valvetronic and direct fuel injection is known as Turbo Valvetronic Direct Injection (TVDI). Cylinder head cover A If there is a complaint about higher oil consumption and at the same time an exhaust turbocharger fouled with oil is diagnosed, then it cannot be immediately concluded that the exhaust turbocharger is faulty. If the fouling is already present after the introduction of the blow-by gases, then the entire engine must be checked for leaks. The cause of an excessive blow-by gas flow rate may be faulty gaskets or crankshaft seals. Untight crankshaft seals may generate oil consumption of up to 3 1/1000 km. Ill BimmerFile.com S55 Engine 13. Service Information 13.2. Fuel preparation 13.2.1. Overview Injectors A Work on the fuel system is only permitted after the engine has cooled down. The coolant temperature must not exceed 40 °C. This measure must be observed without fail, as otherwise there is a risk of fuel being sprayed back on account of the residual pressure in the high-pressure fuel system. When working on the high-pressure fuel system, it is essential to adhere to conditions of absolute cleanliness and to observe the work sequences described in the repair instructions. Even the slightest contamination and/or damage to the screwed fittings of the high-pressure lines can cause leaks. When working on the fuel system of the S55 engine, it is important to ensure that the ignition coils are not fouled with fuel. The resistance of the silicone material is greatly reduced by having contact with fuel. This may result in arching on the spark plug head and thus in misfires. • Before making any modifications to the fuel system, make sure to remove the ignition coils and protect the spark plug holes against of fuel ingress by covering with them with a rag. • Before reinstalling the solenoid valve injectors, remove the ignition coils and ensure the best cleanliness conditions are maintained. • Ignition coils heavily fouled by fuel must be replaced. • The CVO function comprise the system components "Injector" and "Digital Engine Electronics" (DME). These components therefore have to be identified with the vehicle identification number in the EPC in the event of a replacement. • For injectors and a DME which supports the CVO function, the injection quantity compensation during the replacement of one of the components is deleted. • The information and repair instructions in the Integrated Service Technical Application (ISTA) must be observed. 112 BimmerFile.com Bayerische Motorenwerke Aktiengesellschaft Qualifizierung und Training RontgenstraBe 7 85716 UnterschleiBheim, Germany BimmerFile.com