2002 BMW 745i ECU

Downloaded from www.Manualslib.com manuals search engine Intake Manifold
The N62 engine is equipped with a Variable Intake Manifold making it possible to reach a
generous torque curve even at low engine speeds, without incurring losses in engine out-
put at higher speeds. It ensures that the engine exhibits optimum volumetric efficiency
through the entire range of speeds.
The new feature is the Variable Intake Manifold intake pipe length can be adjusted depend-
ing on the engine speed to provide efficient cylinder filling and scavenging. This is deter-
mined by the optimal matching of the intake pipe dimensions, the exhaust system and the
valve timing.
The intake manifold is located in the engine “V” and is mounted on the cylinder head intake
ports.
Function
In order to understand how engine speed relates to volumetric efficiency, the physical
processes within the intake pipe must be taken into consideration.
To ensure that there is good airflow to the engine cylinders, the intake pressure in front of
the intake valve should ideally be high. This means that good airflow (high gas molecule
density) in front of the intake valve is necessary.
8
N62 Engine
42-02-47

Downloaded from www.Manualslib.com manuals search engine This is only possible if the intake valve is closed
and the mass inertia causes the intake air to
flow in front of the closed intake valve. The air is
compressed, the pressure and the air flow
increase.
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1. Closed intake valve
2. Intake manifold
As soon as the intake valve is opened, the pres-
surized intake air flows into the cylinder,
expands and draws the air molecules which fol-
low into the cylinder. The suction waves form in
the intake pipe (moving at sonic speed) in the
opposite direction to the intake air.
These suction waves are reflected in the intake
manifold and create pressure waves which then
move once more at sonic speed in the direction
of the intake valve.
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1. Pressure waves
2. Air manifold
3. Suction waves
The intake pipe is at the optimum length when the pressure waves are at the intake valve
shortly before it is closed. The increase in pressure in front of the intake valve results in
increased air flow to the cylinders once more. This process is described as recharge effect.
The opening angle of the intake valve remains unchanged as the engine speed increases.
The opening time, however, is reduced proportionately (with conventional, non-Valvetronic
engines).
Since the suction waves and pressure waves expand at sonic speed, the suction path
length must be adapted depending on the engine speed to ensure that the tip of the pres-
sure wave reaches the intake valve before it is closed.
9
N62 Engine
42-02-07
42-02-08

Downloaded from www.Manualslib.com manuals search engine 27
N62 Engine
Eccentric Shafts
The eccentric shafts (one per cylinder head) are driven by the
Valvetronic motors and are supported by four caged needle
bearing assemblies for a smooth rotation.
To assist in maintaining the set positions and counter the
valve train torque, a torque compensation spring is mounted
on the end of the shaft for tension.
Magnets are fitted in the (removable) magnetic wheel at the
end of the eccentric shaft. Together with the position sensor,
the Valvetronic Control Module determines the exact shaft
position. The eccentric shaft sensor is mounted through the
cylinder head cover (one per cylinder head) at the back.
The magnetic wheel is secured to the shaft by a bolt and is
indexed by a tab (arrow) to prevent incorrect installation.
Intermediate Lever and Roller Finger
The intermediate lever is positioned further (minimum valve
opening) or closer (maximum valve opening) to the camshaft
by the the progressive “lobe” on the eccentric shaft as it is
rotated. This offers a variable ratio effect for valve actuation.
The roller finger is used to actuate the intake valve.
The intermediate levers and roller fingers are matched (by
classification) to ensure uniform valve lift.
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42-02-3643-02-32
43-02-38
43-02-33

Downloaded from www.Manualslib.com manuals search engine 29
N62 Engine
Bi-VANOS (Variable Camshaft Adjustment)
The N62 features compact infinitely variable vane-type VANOS for the intake and exhaust
camshafts. The VANOS unit is easy to remove and install. The VANOS unit is designed as
an integral component of the chain drive and is secured to the respective camshaft with a
central bolt. The camshaft adjustment rate is 60º (as compared with the crankshaft).
The VANOS unit gear teeth are visibly different to match the new toothed chain. The
VANOS unit for the cylinders 1-4 exhaust shaft has mounting provisions for the vacuum
pump drive. A spring plate is fitted between the VANOS unit and the vacuum pump drive
to reduce wear (3). The V VA
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for intake and exhaust installa-
tion positions.
The VANOS units are supplied with oil via ports in the camshafts. The oil ports are located
on the left and right of the thrust bearing. Depending on the individual VANOS adjustment
direction, the VANOS is supplied with oil via either the rear oil ports (1 & 2) or the front oil
ports (3 & 4). The oil moves through the camshaft to the VANOS units.
VANOS Units
1. VANOS Unit Exhaust Side
2. VANOS Central Bolt
3. Spring Plate
4. VANOS Unit Intake Side
5. Toothed Chain Gear Teeth
VANOS Oil Ports
1&2. Rear Oil Duct with Four Holes
3&4. Front Oil Duct with Four Holes
5. Front Oil Duct Outlets
6&7. Hook Sealing Washer.43-02-39

Downloaded from www.Manualslib.com manuals search engine 30
N62 Engine
Camshaft Sensors
The cam shaft sensors (Hall effect) are mounted through the cylinder head cover. There are
two sensors per cylinder head to monitor the intake and exhaust camshaft positions.
The sensors monitor the impulse wheels
attached to the ends of the camshafts.
Solenoid Valves
The VANOS solenoid valves are mounted through the upper timing case front cover. There
are two solenoids per cylinder head to control the oil flow to the camshaft ports for the
intake and exhaust VANOS units.
The 4/3 way proportional solenoid valve is acti-
vated by the ECM to direct oil flow. The sole-
noid valve is sealed to the front cover by a radi-
al seal and secured by a retaining plate.
N No
ot
te
es
s:
:

42-02-48 Camshaft Sensors
1. Valvetronic Position Sensor
2. Intake Camshaft Position Sensor
3. Exhaust Camshaft Position Sensor
42-02-42

Downloaded from www.Manualslib.com manuals search engine 31
N62 Engine
VANOS Sectional Views
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La
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t:
:
The figures above show a sectional view of one VANOS unit. The VANOS unit is secured
by a central bolt through the hub (7) to the camshaft. The timing chain connects the crank-
shaft with the housing of the unit.
There is a recess in the hub in which the locking pin (6) engages without oil pressure
(sprung). When the solenoid valve is activated to supply oil pressure to the VANOS unit,
the locking pin is compressed and releases the VANOS for adjustment.
The internal blades (9) are spring loaded (10) to provide a seal between the oil pressure
chambers (11 and 12). The torsion spring (3) acts against the camshaft torque.
42-02-4942-02-45
VANO’S Components
1. Housing with Sprocket 7. Hub
2. Front Plate 8. Black Plate
3. Torsion Plate 9. Blade
4. Lock Spring 10. Spring
5. Retaining Plate for Lock Spring 11. Pressure Chamber A
6. Spring Loaded Locking Pin 12. Pressure Chamber B

Downloaded from www.Manualslib.com manuals search engine 32
N62 Engine
H Hy
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Ac
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n:
:
When oil pressure is applied to chamber A, the blades are forced away from the VANOS
housing (counterclockwise). The blades are keyed into the hub which results in the hub
position being rotated in relation to the housing (with sprocket). The hub is secured to the
camshaft which changes the camshaft to sprocket relationship (timing).
The example below shows the a ad
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procedure together with the pressure progres-
sion based on the VANOS unit for the exhaust camshafts.
During this adjustment chamber B is open (through the solenoid) to allow the oil to drain
back through the cylinder head (internal reservoir).
Hydraulic Actuation - Chamber A
1. Front View of Vanos Unit 5. Engine Oil Pump
2. Side View of Vanos Unit 6. Supplied Oil from Pump (Switched Through Solenoid)
3. Camshaft Oil Port (Chamber B) 7. Supplied Oil Pressure (From Engine Oil Pump)
4. Solenoid Valve43-02-45

Downloaded from www.Manualslib.com manuals search engine 47
N62 Engine
Flywheel
The lightweight flywheel is made from a laminated plate. The
starter ring gear is also the increment wheel for engine speed
and crankshaft positioning/misfire detection.
The ring gear is riveted directly to the flexplate (6). The fly-
wheel diameter is 320 mm.
Vibration Damper
The vibration damper is a torsional vibration absorber (axial
design). The outer edge of the damper has a notch (1) to
accept the locating tool when positioning the crankshaft for
initial setting.
The locating tool inserts into the raised mount in the front
cover (2). R Re
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.
Engine Mounting
The engine is secured by two hydraulic damping mounts that are located on the front axle
carrier (structure and function are the same as the E38/M62).
N No
ot
te
es
s:
:

12