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N55 Engine
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Engine Components/Systems Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Technical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Full Load Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Current Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Engine Designation and Engine Identification . . . . . . . . . . . . . . . . . . . . .11
Engine Designation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Breakdown of N55 Engine Designation . . . . . . . . . . . . . . . . . . . . . . . .12
Engine Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Engine Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Engine Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Engine Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Crankcase and Bedplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Crankshaft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Crankshaft Main Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Pistons and Rings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Connecting Rod and Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Oil Pan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Electrionic Volume-controlled Oil Pump . . . . . . . . . . . . . . . . . . . . . . . . . .23
Oil Pump and Pressure Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Oil Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Oil Filtration and Oil Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
Oil Spray Nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Oil Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Oil Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Oil Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Cylinder Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Cylinder Head Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
Crankcase Ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Naturally Aspirated Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Boost Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Valvetrain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
Intake and Exhaust Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Valve Springs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Initial Print Date: 02/10
Revision Date:
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Summary of Contents for BMW N55
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Page 1: Table Of Contents
Engine Designation .........11 Breakdown of N55 Engine Designation ......12 Engine Identification . -
Page 2: Subject Page
Digital Motor Electronics Circuit Diagram ..... .88 N55, MEVD17.2 Circuit Diagram ......88... - Page 3 Subject Page Fuel supply system ........90 Fuel quantity control .
- Page 4 • Describe the specifications of the N55 engine • Identify the internal and external components of the N55 engine • Understand the function of the crankcase ventilation on the N55 engine • Understand the function of the electronic volume control oil pump...
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Page 5: Introduction
Introduction The N55 engine is the successor to the N54. Re-engineering and modifications have made it possible to now use only one exhaust turbocharger. Against the backdrop of reduced costs and improved quality, the technical data have remained virtually the same. -
Page 6: Engine Components/Systems Overview
III system with regard to promoting air turbulence and mixture formation. Crankcase ventilation: • In contrast to the N54, the N55 crankcase ventilation does not use cyclone separators. • The cylinder and head cover have integrated blow-by passages that connect the crankcase ventilation directly to the intake ports. - Page 7 HDE and HPI systems. Digital Motor Electronics (DME): • The DME is mounted on the intake manifold and cooled by intake air. • The location of the DME facilitates the installation of the N55 engine in several current BMW platforms/models. N55 Engine...
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Page 8: Technical Data
EU combined CO2 emission g/km Digital Motor Electronics MSD81 MEVD17.2 Exhaust emission ULEV ULEV II legislation, US BMW Longlife-01 BMW Engine oil specification Longlife-01 FE BMW Longlife-04 Top speed [km/h] Acceleration 0 - 100 km/h/62mph Vehicle curb weight DIN/EU [kg]... -
Page 9: Full Load Diagram
Full Load Diagram Compared to its predecessor, the N55 engine is characterized by lower fuel consumption with the same power output and torque data. Full load diagram E90 335i with N54B30O0 engine compared to the F07 535i with N55B30M0 engine... -
Page 10: Current Models
5800 - 6250 1600 - 4500 The enhanced engine management system of the BMW Z4 sDrive35is and the 335is include an electronically controlled overboost function to briefly increase torque under full load by another 37 ft-lbs. This temporary torque peak of 369 ft-lbs gives the car a significant increase in acceleration for approximately 5 seconds. -
Page 11: Engine Designation And Engine Identification
This training material describes the N55B30M0 in detail. In the technical documentation, the engine designation is used for unique identification of the engine. In the technical documentation you will also find the abbreviated engine des- ignation, i.e. N55, that only indicates the engine type. Item Meaning... -
Page 12: Breakdown Of N55 Engine Designation
This engine identifier is also required for approval by the authorities. The N55 engine further develops this identification system and the code has been reduced from previously eight to seven characters. The engine serial number can be found under the engine identifier on the engine. - Page 13 N55 engine, engine identification and engine serial number Index Explanation 08027053 Individual consecutive engine serial number Engine developer, BMW Group Engine type, straight 6 Change to basic engine concept, turbocharging, Valvetronic, direct fuel injection Operating principle or fuel supply and installation position, petrol engine longitudinal...
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Page 14: Engine Components
Five oil return channels on the intake side (5) also ensure that the blow-by gasses can flow unobstructed from the crankshaft area into the cylinder head and to the crankcase breather in the cylinder head cover. The cooling duct (1) in the engine block is split and coolant flows directly through it. N55 Engine... - Page 15 N55, crankcase with web cooling Index Explanation Cooling duct Cylinder liner Grooved cooling passage Oil return ducts, exhaust side Oil return ducts, intake side N55 Engine...
- Page 16 This enhances power by relieving the unwanted pressure that acts against the downward movement of the pistons. It also enhances crankcase ventilation and adds to oil service life by promoting the movement of blow-by gasses within the engine. N55, ventilation holes in crankcase N55 Engine...
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Page 17: Crankshaft
Crankshaft The crankshaft of the N55 is of lightweight design, at 20.3 kg it’s approximately 3 kg lighter than the crankshaft in the N54 engine. The crankshaft is made from cast iron (GGG70). The counterweights are arranged asym- metrically. There is no incremental wheel installed on the crankshaft. The timing chains are mounted by means of an M18 central bolt. -
Page 18: Pistons And Rings
The second piston ring is a tapered faced Napier type ring. The oil scrape ring is designed as a steel band ring with spring that is also known as VF system. N55 piston with piston rings Index Explanation... -
Page 19: Connecting Rod And Bearings
Connecting Rod and Bearings The size of the connecting rod of the N55 engine is 144.35 mm. A new feature is the specially formed hole in the small end of the connecting rod. This formed hole is machined wider on the lower edges of the wrist pin bushing/bore. This design evenly distributes the force acting on the wrist pin over the entire surface of the rod bushing and reduces the load at the edges, as the piston is forced downward on the power stroke. - Page 20 Due to combustion pressure, the force exerted by the piston via the wrist pin is mainly transmitted to the edges of the rod bushing. N54, connecting rod small end without formed hole Index Explanation Low surface load High surface load N55 Engine...
- Page 21 Lead-free bearing shells are used on the large connecting rod end. The material G-488 is used on the connecting rod side and the material G-444 on the bearing cap side. The size M9 x 47 connecting rod bolts are the same on the N55 and N54 connecting rod.
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Page 22: Oil Pan
Ducts are provided for the oil supply to the vacuum pump as it is now lubricated by filtered oil and not by unfiltered oil as on the N54 engine. N55, bedplate with oil pump and oil deflector Index Explanation... -
Page 23: Electrionic Volume-Controlled Oil Pump
The oil pressure in the system (downstream of the oil filter) acts on the slide against the force of a compression springs in the control oil chamber. The slide element rotates about a pivot axis. N55, oil pump Index Explanation... -
Page 24: Oil Pump And Pressure Control
It is operated based on a characteristic map within the DME (ECM) which in turn is based on feedback from the oil pressure sensor. The N55 uses a special oil pressure sensor for this purpose which functions in the similar way as the HPI fuel pressure sensor. - Page 25 Lubricating points, engine block Outlet valve at the filter Oil spray nozzles, piston crowns Oil filter Note: The N53 hydraulic circuit diagram shown is for explanation of the oil pressure control only, and does not apply directly to the N55 engine. N55 Engine...
- Page 26 N55, oil pump and pressure control valve Index Explanation Oil pressure control valve Oil pump Oil pressure sensor N55 Engine...
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Page 27: Oil Supply
Oil Supply The following graphics show an overview of the oil circuit of the N55. Compared to the N54 engine, there are considerably fewer oil ducts in the cylinder head. This is mainly due to the use of the new VANOS solenoid valves. - Page 28 Oil duct for exhaust camshaft lubrication Hydraulic valve lash adjustment Connection to exhaust turbocharger lubrication Connection for oil spray nozzles Crankshaft bearing Oil duct for oil pressure control Oil duct for oil pressure control Oil duct for vacuum pump lubrication Vacuum pump N55 Engine...
- Page 29 N55, oil passages front view N55 Engine...
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Page 30: Oil Filtration And Oil Cooling
The oil filter housing is made from Duroplast. Based on the application, two types of engine oil coolers may be used. Depending on the oil temperature, a thermostat on the oil filter housing controls the oil flow through the oil cooler. N55 Engine... -
Page 31: Oil Spray Nozzles
Oil Spray Nozzles The N55 engine is equipped with oil spray nozzles for the purpose of cooling the piston crown. A special tool is required for positioning the oil spray nozzles. Oil Pressure Since the N55 engine has an oil pump with electronic volumetric flow control, it is neces- sary to measure the oil pressure precisely. -
Page 32: Cylinder Head
Direct fuel injection, turbocharging and Valvetronic systems are combined for the first time on a BMW 6-cylinder engine. The cylinder head of the N55 engine is a new develop- ment. It features a very compact design and is equipped with third generation Valvetronic. -
Page 33: Cylinder Head Cover
The non-return valves ensure that the blow-by gasses are reliably added to the intake air in both engine modes (NA and Boost) The N55 engine is equipped with a vacuum-controlled crankcase ventilation system; therefore, a regulated negative pressure of approximately 38 mbar is maintained. -
Page 34: Crankcase Ventilation
(12) in the duct to the charge air intake pipe. The blow-by gasses flow via a distribution rail integrated in the cylinder head cover, through the intake passages (16) in the cylinder head, which lead directly into the intake ports, ahead of the valves. N55 Engine... - Page 35 N55, crankcase ventilation, naturally-aspirated mode N55 Engine...
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Page 36: Boost Mode
The increased demand for fresh air creates a vacuum in the clean air pipe between the turbocharger and intake silencer. This vacuum is sufficient to open the non-return valve (12) and draw the blow-by gasses via the pressure control valve. N55 Engine... - Page 37 N55, crankcase ventilation, turbocharged (boost) mode N55 Engine...
- Page 38 Note: If a customer complains about high oil consumption and oil is discovered in the turbocharger, it should not be immediately assumed that the turbocharger is defective. If the oil is present in the fresh air pipe (before the turbocharger) then the entire engine should be checked. N55 Engine...
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Page 39: Valvetrain
Valvetrain The following graphic shows the design of the cylinder head on the N55 engine with Valvetronic III and direct fuel injection. N55, overview of valvetrain Note: Notice the hollow, lightweight design of the camshafts (7) and the blow-by passages leading into the intake ports (15). -
Page 40: Intake And Exhaust Valves
The valve stems have a diameter of 5 mm on the intake valve and 6 mm on the exhaust valve. The larger diameter exhaust valve are hollow and filled with sodium. In addition, the valve seat of the exhaust valves are reinforced. Valve Springs The valve springs are different for the intake side and exhaust side. N55 Engine... -
Page 41: Camshafts
Lightweight camshafts as well as cast camshafts or a mixture of both were installed in N54 engines. Only lightweight construction camshafts are used on the N55 engine. The lightweight camshafts for the N55 are manufactured in an internal high pressure forming process called hydroforming. The exhaust camshaft features bearing races and is encapsulated in a camshaft housing. -
Page 42: Valve Timing
(max.-min. spread) Opening period intake camshaft [°crankshaft] Opening period exhaust camshaft [°crankshaft] Note: The N55 has a larger intake and exhaust VANOS adjustment range as well as larger intake valve lift, and cam duration than the N54 engine. N55 Engine... -
Page 43: Vanos System
N54, VANOS with oil supply Index Explanation Main oil duct VANOS solenoid valve, intake side VANOS solenoid valve, exhaust side Chain tensioner Non return valve, exhaust side Non return valve, intake side VANOS adjustment unit, exhaust side VANOS adjustment unit, intake side N55 Engine... -
Page 44: Overview
VANOS units. The aluminum VANOS units are much lighter and are also less susceptible to soiling. It can be seen by comparing the N54 VANOS system with the N55 VANOS that fewer oil passages are required and that the non-return valves are no longer on the cylinder head but rather incorporated into the solenoid valves on N55. -
Page 45: Vanos Solenoid Valves
The non-return valve with screen filter used on the N54 engine have now been integrat- ed in the VANOS solenoid valves on the N55 engine. This measure has made it possible to reduce the number of oil ducts in the cylinder head. The screen filters on the VANOS solenoid valve ensure trouble-free operation and reliably prevent the VANOS solenoid valve from sticking due to dirt particles. -
Page 46: Valvetronic Iii
The advantage of this measure is that the combustion retardation is reduced by approxi- mately 10° of crankshaft rotation. The combustion process takes place faster and a larger valve overlap can be achieved, thus considerably reducing NOx emissions. N55 Engine... - Page 47 N55, Top of the combustion chamber Index Explanation Quench area Exhaust valves Spark plug Fuel injector Intake valve Masking Quench area N55 Engine...
- Page 48 Valvetronic as there is now no need wait for the intake air manifold to be filled. The subsequent torque buildup as the turbocharger starts up can be acceler- ated with the partial lift setting at low engine speed. This effectively flushes out residual gas, thus resulting in faster torque build-up. N55 Engine...
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Page 49: Combustion Chamber Geometry
The following graphic shows the arrangement of the individual components in the com- bustion chamber. It can be seen that the BMW (spray-guided) high precision injection (HPI) system is not used but rather a Bosch solenoid valve fuel injector with multi-hole nozzle. -
Page 50: Valve Lift Adjustment Overview
As can be seen from the following graphic, the installation location of the servomotor has changed with Valvetronic III. Another new feature is that the eccentric shaft sensor is no longer mounted on the eccentric shaft but has been integrated into the servomotor. N55, valve lift adjustment Viewed from the Front View... - Page 51 The Valvetronic III servomotor contains a sensor for determining the position of the motor and the eccentric shaft. The servomotor is lubricated with engine oil by means of an oil spray nozzle (1) aimed directly at the worm drive and the eccentric shaft mechanism. N55, design of valve lift adjustment Index Explanation...
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Page 52: Valvetronic Servomotor
The duty cycle is between 5% and 98%. Index Explanation Index Explanation Socket Rotor with four magnets Worm shaft Sensor Needle bearing Stator Bearing cover Housing Magnetic sensor wheel Bearing N55 Engine... -
Page 53: Belt Drive And Auxiliarly Components
Belt Drive and Auxiliarly Components The belt drive has two deflection pulleys and one double ribbed belt. N55, Belt drive Index Explanation Index Explanation Belt pulley, alternator Deflection pulley Deflection pulley Vibration absorber with belt pulley Belt pulley, A/C compressor... -
Page 54: Vibration Damper
Vibration Damper A single-mass vibration damper is used on the N55 engine. The belt pulley is mounted on the secondary pulley. Compared to the N54 engine, this design layout additionally reduces the belt load as the vulcanization decouples the belt pulley with flywheel mass from the crankshaft. - Page 55 N55, vibration damper Index Explanation Secondary belt pulley with flywheel mass Flange Vulcanization N55 Engine...
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Page 56: Air Intake And Exhaust System
Air Intake and Exhaust System Air Intake System Several functions of the air intake system have been optimized for the N55 engine: • The unfiltered air is routed up to the intake silencer (similar to the N54 engine). • The filtered air duct is completely new and simplified to accommodate the new turbocharger. - Page 57 N55, Air Intake and Exhaust System N55 Engine...
- Page 58 Heated charge air Cooled charge air Intake snorkel Unfiltered air pipe Intake silencer Filter element Air intake silencer cover Hot-film air mass meter Crankcase ventilation connection Exhaust turbocharger Charge-air pipe Intercooler Charge air pipe Boost pressure-temperature sensor Intake air manifold N55 Engine...
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Page 59: Intake Manifold
The engine control unit is mounted on the intake manifold. The intake air is used to cool the engine control unit. Thanks to this arrangement, the engine comes down the assembly line completely assembled with the control unit, the sensors, and actuators already connected. N55, intake system with DME control unit Index Explanation Index... -
Page 60: Fuel Tank Ventilation System
The fuel vapors are stored in a charcoal canister and then fed via the fuel tank vent valve to the combustion process. It was also necessary to adapt this system to all the given conditions related to turbocharging. N55, fuel tank ventilation system Index Explanation... -
Page 61: Exhaust Manifold
(1-3) feed one scroll (duct 1) of the turbo, while the last three (4-6) feed the second scroll (duct 2). The exhaust manifold and turbocharger are welded together to form one component. N55, attachment of exhaust manifold and turbocharger to engine block Index Explanation... -
Page 62: Turbocharger
Turbocharger The N55 is equipped with a single twin scroll turbocharger instead of two separate small turbochargers as on the N54 engine. The following graphics shows the operating princi- ple of the twin scroll turbocharger. Twin scroll turbocharger rear view... - Page 63 Exhaust duct 1 (cylinders 1 - 3) Wastegate valve Exhaust duct 2 (cylinders 4 - 6) Lever arm, wastegate valve Connection to catalytic converter Vacuum unit for wastegate valve Inlet from intake silencer Diverter valve Ring channel Oil return Outlet to intercooler Coolant return N55 Engine...
- Page 64 Vacuum unit for wastegate valve Exhaust duct 2 (cylinders 4 - 6) Diverter valve Connection to catalytic converter By-pass Inlet from intake silencer Turbine wheel Ring channel Compressor wheel Outlet to intercooler Cooling duct Wastegate valve Turbine shaft Lever arm, wastegate valve N55 Engine...
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Page 65: Function Of The Twin Scroll Turbocharger
N54 engine is that the diverter valve is not operated pneumatically. The diverter valve on the N55 engine is an electric actuator that is controlled directly by the DME. The number of components has been greatly reduced by positioning the diverter valve on the turbocharger compressor housing. -
Page 66: Catalytic Converter
Ceramic structure 1 has a volume of 1.2 liters, a diameter of 125 mm, and contains 600 cells. Ceramic structure 2 has a volume of 1.5 liters, a diameter of 125 mm, and contains 400 cells. N55, catalytic converter Index Explanation Index... -
Page 67: Exhaust System
With the single twin scroll turbocharger, the design of the exhaust system is less compli- cated than that of the N54 engine, with two turbochargers. In addition to a “near-engine” catalytic converter design, the exhaust system also features a center silencer and two rear silencers. N55, exhaust system F07 Index Explanation Exhaust manifold... -
Page 68: Vacuum System
Vacuum System The N55 engine is equipped with a vacuum pump for generating the vacuum required by the brake booster and the auxiliary consumers (exhaust flaps and wastegate). A vacuum accumulator (built into the cylinder head cover) is used to ensure there is sufficient vacuum for the wastegate valve at all times. -
Page 69: Vacuum Pump
The vacuum pump is similar to that used on the N63 engine. It is a two-stage pump and therefore has two connections. The first stage is for the brake booster and the second for the auxiliary consumers. N55, vacuum pump Index Explanation... - Page 70 This solution takes into account the different requirements for the brake booster and the auxiliary consumers. N55, delivery rate of the two-stage vacuum pump Index Explanation Vacuum Time Delivery rate for auxiliary consumers Delivery rate for brake booster N55 Engine...
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Page 71: Fuel Injection
Fuel Injection The high pressure fuel injection system (HDE) is used on the N55 engine. In contrast to high precision injection (HPI), HDE uses solenoid fuel injectors with multi-hole nozzles. The following overview shows the complete fuel injection system. The system is similar to the N54 fuel injection. -
Page 72: Fuel Pressure Sensor
The fuel pressure sensor known from the N54 and N63 is used. In the event of the fuel pressure sensor failing, the electric fuel pump continues operation at 100% delivery rate as from terminal 15 ON. N55 Engine Index Explanation Index... -
Page 73: High Pressure Fuel Pump
A pressure of 200 bar is only required at high load and low engine speed. The high pressure pump is of the same design as the high pressure pump used on the N54 engine. N55, fuel pressure diagram Index Explanation... -
Page 74: Fuel Injectors
Particular care must be taken when working on the fuel system of the N55 engine to ensure that the ignition coils are not wet with fuel. The resistance of the silicone insulating material of the coils is greatly reduced by the contact with fuel. -
Page 75: Cooling System
Cooling System The cooling system of the N55 is enhanced with additional oil cooling. Two different types of oil cooling systems are used depending on the model and applica- tion. In the “hot climate” version, heat transfer from the engine oil to the engine coolant is avoided by separating the oil cooler from the engine coolant circuit. - Page 76 Heater coil Characteristic map thermostat Electric coolant pump Exhaust turbocharger Heating heat exchanger Coolant valve Oil-to-coolant heat exchanger Coolant temperature sensor Engine oil thermostat (hot climate version) Expansion tank Coolant level switch Equalization line Auxiliary radiator Electric fan N55 Engine...
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Page 77: Components
Components N55, Cooling System Components Index Explanation Index Explanation Auxiliary radiator Bypass line for small cooling circuit Coolant feed line to auxiliary radiator Thermostat Oil-to-coolant heat exchanger Electric coolant pump Coolant feed line to oil-to-coolant heat exchanger Exhaust turbocharger supply line... - Page 78 The auxiliary radiator is connected to the radiator by means of parallel coolant lines, thus increasing the cooling surface area. This system is combined with an oil-to-coolant heat exchanger mounted on the oil filter housing. (See component “C” in the previous graphic.) N55, auxiliary radiator Index Explanation Radiator...
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Page 79: Oil Cooler
Oil Cooler N55, engine oil cooling, “hot climate” Index Explanation Oil filter module Thermostat Oil cooler lines Engine oil to air heat exchanger (oil cooler) Note: Most current US vehicles use a separate engine oil to air heat exchanger to cool the engine oil (hot climate version). -
Page 80: Coolant Passages
The coolant passages in the cylinder head are also used for indirect cooling of the fuel injectors. The following graphic clearly shows that the coolant flows over the valves and the fuel injectors, thus reducing the heat transfer to the components to a minimum. N55, casting of the coolant passages in cylinder head Index Explanation... - Page 81 Coolant can flow along these grooves from one side of the block to the other, thus cooling the deck area between the cylinders. N55, coolant passages and web cooling of the engine block Index Explanation...
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Page 82: Engine Electrical System
• Engine wiring harness is divided into six individual modules • All electrical components on the engine are supplied directly via the DME • The E-box is no longer need • 211 pins are available • The plug-in connectors are water-tight N55, wiring harness routing N55 Engine... -
Page 83: Circuit Diagram
Circuit Diagram N55, circuit diagram, connection to vehicle electrical system N55 Engine... - Page 84 Fuel tank leak diagnostic module Electronic fuel pump controller Rear power distribution box Intelligent battery sensor Battery power distribution box Exhaust flap changeover valve Diagnosis socket (engine speed signal) Accelerator pedal module Instrument cluster Car Access System Central Gateway Module N55 Engine...
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Page 85: Engine Cooling Circuit Diagram
Engine Cooling Circuit Diagram N55, circuit diagram, engine cooling N55 Engine... - Page 86 Mechanical air flap control Electric air flap control Digital Motor Electronics Front power distribution box Junction box electronics Junction box Electric fan relay Rear power distribution box Electric fan relay (only for 850 Watt and 1000 Watt electric fan) N55 Engine...
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Page 87: Digital Motor Electronics (Dme/Ecm)
Digital Motor Electronics (DME/ECM) The N55 engine is equipped with the Bosch engine management MEVD17.2 : • The MEVD17.2 is integrated in the intake system and is cooled by the intake air. • The MEVD17.2 is FlexRay-compatible and directly supplies voltage to the sensors and actuators. -
Page 88: Digital Motor Electronics Circuit Diagram
Digital Motor Electronics Circuit Diagram N55, MEVD17.2 Circuit Diagram N55 Engine... - Page 89 Active cooling air flap control Oil pressure control valve Intelligent battery sensor (IBS) Electropneumatic pressure converter Dynamic stability control (DSC) (EPDW) for wastegate valve Quantity control valve Central Gateway Module (ZGM) 29-34 Fuel injectors Integrated Chassis Management (ICM) N55 Engine...
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Page 90: Functions
The engine management controls the boost pressure with the wastegate valve at the turbocharger. An electropneumatic pressure converter (vacuum solenoid) receives the signals from the engine management and supplies vacuum to open the wastegate valve when the specified maximum boost pressure is reached. N55 Engine... -
Page 91: Engine Cooling
Adapted to the relevant driving situation, the engine control unit can now regulate a defined operating range. In this way it is possible to influence the fuel consumption and power output through the cooling system. N55 Engine... -
Page 92: System Protection
The function of the new crankshaft sensor is identical to that of the crankshaft sensors used for the automatic engine start-stop function (MSA). The engine reversal detection is required for the MSA function. (MSA is not currently offered in the US.) N55 Engine... - Page 93 N55, location of crankshaft sensor Index Explanation Direction of view towards crankshaft Same view without starter Connector Dust seal Sensor Multi-pole trigger wheel N55 Engine...
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Page 94: Ignition Coil
Sensor Ignition Coil New ignition coils have been developed for the N55 engine. The ignition coils have improved electromagnetic compatibility and are sturdier. The insulation has been rein- forced with silicone and a metal collar shielding compared to the coils used on previous engines. -
Page 95: Oil Pressure Sensor
The sensor design is identical to that of the (high) fuel pressure sensor. The DME supplies a voltage of 5 Volt to the oil pressure sensor. N55, oil pressure sensor Oxygen Sensors A new connector is used for the oxygen sensors. -
Page 96: Oxygen Sensor Before Catalytic Converter
Oxygen sensor after catalytic converter The oxygen sensor after catalytic converter is also known as the monitoring sensor. The familiar Bosch LSF 4.2 monitoring sensor is used. N55 Engine... -
Page 97: Hot-Film Air Mass Meter
Hot-film air mass meter High Pressure Fuel Injector Valve The HDEV5.2 solenoid type injector valves used on the N55 engine are a new development. 1 Booster phase: Opening of the HDEV5.2 is initiated in the booster phase by a high booster voltage from the DME. -
Page 98: Function
Function N55, actuation phases of the HDEV5.2 Index Explanation Index Explanation DME actuation signal Booster phase Current flow HDEV5.2 Energizing phase Voltage at HDEV5.2 Hold phase Switch off phase N55 Engine... -
Page 99: Service Information
Fuel Injectors In order to remove the N55 fuel injectors from the cylinder head, special tool #13 0 270 must be utilized. Failure to use the special tool will result in damage to the injectors. Note: Do not open the high pressure fuel injection system if the coolant temperature is above 40°C . -
Page 100: Ignition Coils
Ignition Coils The ignition coils of the N55 have been redesigned for better rigidity and durability. Particular care must be taken when working on the fuel system to ensure that the ignition coils are not wet with fuel.
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