2005 BMW 745i N62B44 Engine Workshop Manual

Downloaded from www.Manualslib.com manuals search engine Throttle Valve
The throttle valve on the N62 is not necessary for engine load control. This is carried out
by the intake valves variable lift adjustment.
The tasks of the throttle valve are:
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Airflow is controlled by the throttle valve during the starting procedure when the air temp-
erature is between 20 ºC and 60 ºC, .
If the engine is at operating temperature, it will be switched to non-throttle mode approx-
imately 60 seconds after start up. In cold conditions however, the engine is started with
the throttle valve fully opened because this has a positive effect on the starting characteris-
tics.
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This vacuum is needed to exhaust the blow-by gases from the crankcase and the fuel
vapors from the activated charcoal filter.
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If the Valvetronic system should fail, the throttle valve implements conventional load con-
trol).
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N62 Engine
42-02-25
Throttle Valve
• Throttle Valve Housing with Throttle Valve.
• Throttle Valve Actuator
• Two Throttle Valve Potentiometers

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.
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N62 Engine
42-02-07
42-02-08

Downloaded from www.Manualslib.com manuals search engine Each cylinder has its own intake pipe (1) which is connected to the manifold volume (6) via
a rotor (3). The rotors are supported by one shaft (4) per cylinder bank.
The second shaft, from which the rotor for the opposite cylinder bank is adjusted, is turned
by spur gears (5) in the opposite direction from the driven shaft.
The intake air flows via the manifold volume through the funnel (2) and on to the cylinders.
The intake path length is set as the rotor turns.
The intake path length can be adjusted according to the engine speed. Adjustment from
the long to short intake path begins at 3,500 rpm. If the engine speed increases, the intake
path length is progressively reduced, up to 6,200 rpm.
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N62 Engine
42-02-09
The Variable Intake Manifold
1. Intake Port
2. Funnel
3. Rotor
4. Shaft
5. Spur Gears
6. Manifold Volume

Downloaded from www.Manualslib.com manuals search engine The intake path length is determined by the fun-
nel position. If the engine speed is less than
3,500 rpm, the funnel is in the longer intake
path length position.
This means that the intake air must cover a
longer path to reach the cylinders.
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When an engine speed of 6,200 rpm is
reached, the rotor is adjusted to the shorter
intake path position. The intake path to the
cylinders is now short.
The funnel can be progressively adjusted to any
point between the long/short intake path posi-
tions.
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Funnel adjustment is carried out by the drive unit, which is located on the rear of the intake
manifold housing. The drive motor adjusts the drive shaft with funnels (cylinder bank 1-4).
The second shaft with funnels for cylinder bank 5-8 is synchronously adjusted by the spur
gears.
The drive motor is controlled by the ECM and
provides feedback about the funnel position via
an integral potentiometer.
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N62 Engine
42-02-11
42-02-10
42-02-81

Downloaded from www.Manualslib.com manuals search engine Crankcase Venting System
The crankcase vapors (a result of combustion blow-by gasses) are led out of the crank-
case and back into the combustion chamber via the intake manifold. The blow-by gasses
contain droplets of oil which must be separated. The oil is returned to the sump while the
blow-by gasses are led into the intake pipe for combustion.
The engine performance is affected by the introduction of crankcase vapors into the com-
bustion process, particularly in idle speed ranges. This influence is monitored by lambda
regulation.
The crankcase vapors are carried from the crankcase and into the cylinder head covers
through labyrinth separators (one per cylinder head). The oil which accumulates on the
walls of the labyrinth separators flows into the cylinder head via a siphon and from there
back to the sump.
The remaining vapors are passed to the engine for combustion via the pressure control
valve (5) in the intake manifold. One labyrinth separator with a pressure control valve is inte-
grated in each of the two cylinder head covers.
The throttle valve is controlled so that there is always a 50 mbar vacuum in the intake man-
ifold. The pressure control valve regulates the crankcase pressure to a low 0-30 mbar.
12
N62 Engine
43-02-12 Cylinder Head Cover
1-4. Opening for Spark Plugs
5. Pressure Control Valve
6. Opening Valvetronic Motor
7. Opening Valvetronic Sensor
Connector
8. Camshaft Sensor

Downloaded from www.Manualslib.com manuals search engine Exhaust System
The exhaust system is completely redesigned for the N62B44 engine. It has been opti-
mized in terms of cylinder filling, scavenging, sound level and rapid catalytic converter light-
off.
Exhaust Manifold with Catalytic Converter
Each cylinder bank is equipped with a four into two into one exhaust manifold. The mani-
fold and the catalytic converter housing together form one component. A ceramic-bed pre-
catalytic converter and a ceramic-bed main catalytic converter are arranged one behind the
other in the catalytic converter housing.
The mounting for the broadband planar oxygen sensors (Bosch LSU) and the secondary
oxygen sensors is located in front of and behind the catalytic converter.
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N62 Engine
42-02-13 Exhaust System
1. Manifold with Integrated Catalytic Converter
2. Broadband Planar Oxygen Sensors
3. Secondary Oxygen Sensors
4. Exhaust Pipe with Front Silencer
5. Center Silencer
6. Exhaust Gas Flap
7. Rear Silencers

Downloaded from www.Manualslib.com manuals search engine Silencers
• A 1.8 liter capacity front silencer has been fitted for each cylinder bank.
• A single 5.8 liter center silencer is fitted downstream of the two front silencers.
• The resonator type rear silencers have capacities of 12.6 and 16.6 liters.
Exhaust Gas Flap
The 12.6 liter rear silencer is fitted with an exhaust gas flap to keep noise to a minimum at
engine idle speed and low rpm. The exhaust gas flap is opened allowing additional flow
when:
• The a transmission gear is engaged a an
nd
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• The engine speed is above 1,500 rpm
A vacuum-controlled diaphragm (actuator mounted on the silencer) opens and closes the
exhaust gas flap. The exhaust gas flap is closed with vacuum, and is sprung open by the
actuator (when vacuum is not present). The procedure is carried out using a solenoid valve
which is electrically controlled by the ECM.
Secondary Air System
Blowing additional air (secondary air) into the cylinder head exhaust ducts during the warm-
up phase results in a thermal secondary combustion which results in a reduction of the
non-combusted hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas. The
energy generated during this process heats up the catalytic converter faster during the
warm-up phase, and increases it’s conversion rate.
14
N62 Engine
43-02-05
Secondary Air System
1. Air Intake Duct
2. Air Cleaner housing with Intake Air Silencer
3. Intake Pipe with HFM (Hot-Film Air-Mass
Sensor)
4. Non-return Valves
5. Secondary Air Pump