engine BMW 740i 2000 E38 M62TU Engine User Guide

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INTEGRAL ELECTRIC THROTTLE SYSTEM (EML)
FUNCTIONAL DESCRIPTION
When the accelerator pedal
is moved, the PWG pro-
vides a change in the mon-
itored signals. The ME 7.2
compares the input signal
to a programmed map and
appropriately activates the
EDK motor via proportional-
ly high/low switching cir-
cuits. The control module
self-checks it’s activation of
the EDK motor via the EDK
feedback potentiometers.
Requirements placed on the Electric Throttle System:
• Regulate the calculated intake air load based on PWG input signals and programmed
mapping.
• Control idle air when LL detected with regard to road speed as per previous systems.
• Monitor the driver’s input request for cruise control operation.
• Automatically position the EDK for accurate cruise control (FGR) operation.
• Perform all DSC III throttle control interventions.
• Monitor and carryout max engine and road speed cutout.

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PWG SIGNAL MONITORING & PWG FAILSAFE OPERATION:
• As a redundant safety feature the PWG provides two separate signals from two integral
potentiometers (Pot 1 and Pot 2) representing the driver’s request for throttle activation.
• If the monitored PWG potentiometer signals are not plausible, ME 7.2 will only use the
lower of the two signals as the driver’s pedal request input providing failsafe operation.
Throttle response will be slower and maximum throttle position will be reduced.
• When in PWG failsafe operation, ME 7.2 sets the EDK throttle plate and injection time
to idle (LL) whenever the brake pedal is depressed.
• When the system is in PWG failsafe operation, the instrument cluster matrix display will
post “Engine Emergency Program” and PWG specific fault(s) will be stored in memory.
EDK FEEDBACK SIGNAL MONITORING & EDK FAILSAFE OPERATION:
• The EDK provides two separate signals from two integral potentiometers (Pot 1 and Pot
2) representing the exact position of the throttle plate.
• EDK Pot 1 provides the primary throttle plate position feedback. As a redundant safe-
ty feature, Pot 2 is continuously cross checked with Pot 1 for signal plausibility.
• If plausibility errors are detected between Pot 1 and Pot 2, ME 7.2 will calculate the
inducted engine air mass (from HFM signal) and only utilize the potentiometer signal that
closely matches the detected intake air mass.
- The ME 7.2 uses the air mass signalling as a “virtual potentiometer” (pot 3) for a
comparative source to provide failsafe operation.
- If ME 7.2 cannot calculate a plausible conclusion from the monitored pots (1 or 2
and virtual 3) the EDK motor is switched off and fuel injection cut out is activated
(no failsafe operation possible).
• The EDK is continuously monitored during all phases of engine operation. It is also
briefly activated when KL 15 is initially switched on as a “pre-flight check” to verify it’s
mechanical integrity (no binding, appropriate return spring tension, etc). This is accom-
plished by monitoring both the motor control amperage and the reaction speed of the
EDK feedback potentiometers. If faults are detected the EDK motor is switched off and
fuel injection cut off is activated (no failsafe operation possible). The engine does how-
ever continue to run extremely rough at idle speed.
• When a replacement EDK is installed, the ME 7.2 adapts to the new component
(required amperage draw for motor control, feedback pot tolerance differences, etc).
This occurs immediately after the next cycle of KL 15 for approximately 30 seconds.
During this period of adaptation, the maximum opening of the throttle plate is 25%.

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INPUT SIGNALS/COMPONENTS
CAMSHAFT POSITION SENSORS
Located on the upper timing case covers, the camshaft position sensors monitor the posi-
tion of the camshafts to establish start of ignition firing order, set up sequential fuel injection
triggering and for accurate camshaft advance-retard (VANOS) timing feedback.
Each intake camshaft’s advance-retard angles are adjusted simultaneously yet indepen-
dently. For this reason ME 7.2 requires a camshaft position sensor on each cy linder bank
for accurate feedback to monitor the VANOS controlled camshaft positioning.
The sensors are provided with operating power from the ECM main relay. The sensors pro-
duce a unique asymmetrical square-wave signal representative of the impulse wheel shape.
The sensors are new in the fact that they are “active” hall effect sensors. Active hall sen-
sors provide:
• low signal when a tooth of the camshaft impulse wheel is located in front of the sensor
• high signal when an air gap is present.
The active hall sensors supply a signal representative of camshaft position even before the
engine is running. The ME 7.2 determines an approximate location of the camshafts posi-
tions prior to engine start up optimizing cold start injection (reduced emissions.)
UNIQUE SIGNAL
AS SEEN IN
MEASUREMENT
SYSTEM
OSCILLOSCOPE

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ACCELERATOR PEDAL SENSOR (PWG)
The driver's application of the accelerator pedal is monitored by a PWG sensor in the dri-
ver's footwell as with previous non-bowden cable EML systems.
The PWG provides two separate variable voltage signals to the ME 7.2 control module for
determining the request for operating the Electric Throttle Valve (EDK) as well as providing
a kickdown request with automatic transmission vehicles.
The ME 7.2 monitors the changing signal
ranges of both circuits as the pedal is pressed
from LL to VL.
• In vehicles equipped with an automatic transmission (A5S 440Z), the ME 7.2 recognizes
the max pedal value (4.5V) as a kickdown request and signals the AGS via CAN bus.
PWG SIGNAL MONITORING & PWG FAILSAFE OPERATION:
• If the monitored PWG potentiometer signals are not plausible, ME 7.2 will only use the
lower of the two signals as the driver’s pedal request input providing failsafe operation.
Throttle response will be slower and maximum throttle position will be reduced.
• When in PWG failsafe operation, ME 7.2 sets the EDK throttle plate and injection time
to idle (LL) whenever the brake pedal is depressed.
• When the system is in PWG failsafe operation, the instrument cluster matrix display will
post “Engine Emergency Program” and PWG specific fault(s) will be stored in memory.

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EDK THROTTLE POSITION FEEDBACK SIGNALS
The EDK throttle plate position is monitored by two integrated potentiometers. The poten-
tiometers provide DC voltage feedback signals as input to the ME 7.2 for throttle and idle
control functions.
Potentiometer signal 1 is the primary signal, Potentiometer sig-
nal 2 is used as a plausibility cross-check through the total
range of throttle plate movement.
EDK FEEDBACK
SIGNAL MONITORING & FAILSAFE OPERATION:
• If plausibility errors are detected between Pot 1 and Pot 2, ME 7.2 will calculate the
inducted engine air mass (from HFM signal) and only utilize the potentiometer signal that
closely matches the detected intake air mass.
- The ME 7.2 uses the air mass signalling as a “virtual potentiometer” (pot 3) for a
comparative source to provide failsafe operation.
- If ME 7.2 cannot calculate a plausible conclusion from the monitored pots (1 or 2
and virtual 3) the EDK motor is switched off and fuel injection cut out is activated
(no failsafe operation possible).
• The EDK is continuously monitored during all phases of engine operation. It is also
briefly activated when KL 15 is initially switched on as a “pre-flight check” to verify it’s
mechanical integrity (no binding, appropriate return spring tension) by monitoring the
motor control amperage and the reaction speed of the EDK feedback potentiometers.
If faults are detected the EDK motor is switched off and fuel injection cut off is activat-
ed (no failsafe operation possible). The engine does however continue to run extreme-
ly rough at idle speed.

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CAN BUS
• The CAN bus consists entirely of a twisted pair wire set. This configuration eliminates
the need for a ground shield.
• The Engine Control Module has two CAN bus communication ports, one dedicated to
AGS and the other for the balance of the vehicle’s CAN bus control modules.
• This configuration improves the reliability of CAN bus signalling. If an open occurs in one
area, the other control systems can still communicate on either side of the open.
• However, signals not reaching their intended recipients will cause CAN bus faults to be
stored in the affected systems.

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OUTPUT CONTROL FUNCTIONS
FUEL PUMP RELAY CONTROL
ME 7.2 controls the fuel pump relay as with previous systems with regard to engine speed
input for continual activation of the relay.
The ME 7.2 will switch off the fuel pump relay when an airbag is activated as an addition-
al safety function. The signal is passed from the MRS III control module to the ME 7.2 over
the CAN line
E BOX FAN CONTROL
The E Box fan is controlled by ME 7.2. The control module
contains an integral NTC temperature sensor for the pur-
pose of monitoring the E box temperature and activating the
fan.
When the temperature in the E-Box exceeds predetermined
values, ME 7.2 provides a switched ground for the E Box fan
to cool the E box located control modules.
With every engine start-up, ME 7.2 briefly activates the fan
ensuring continued fan motor operation for the service life of
the vehicle. This feature is intended to prevent fan motor
“lock up” from lack of use due to pitting or corrosion over
time.

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ELECTRIC THROTTLE VALVE (EDK) CONTROL
• The throttle valve assembly of the M62 TU is an
electric throttle valve (EDK) controlled by an inte-
gral EML function of the ME 7.2.
• The throttle plate is positioned by a gear reduction
DC motor drive.
• The motor is controlled by proportionately
switched high/low PWM signals at a basic fre-
quency of 2000 Hz.
• Engine idle speed control is a function of the EDK.
Therefore, the M62 TU does not require a separate
idle control valve.
HARNESS
CONNECTORMOTOR
REDUCTION
GEARS
POTENTIOMETER WIRES
THROTTLE
PLATE
EDK ADAPTATION
PROCEDURE:
When a replacement EDK
is installed the adaptation
values of the previous EDK
must be cleared from the
ME 7.2 control module.
1. From the Service
Function Menu of the
DIS/MoDiC, clear
adaptation values.
2. Switch the ignition OFF
for 10 seconds.
3. Switch the ignition ON
(KL 15). At approxi-
mately 30 seconds the
EDK is briefly activated
allowing the ME 7.2 to
“electrically learn” the
new component.
This procedure is also necessary after replacing an ME 7.2 control module. However, the
adaptation values do not require clearing since they have not yet been established.

FUNCTION
The DC Motor LDP ensures accurate fuel system leak detection for leaks as small as
0.5mm (.020”). The pump contains an integral DC motor which is activated directly by the
engine control module. The ECM monitors the pump motor operating current as the mea-
surement for detecting leaks.
The pump also contains an ECM controlled change over valve that is energized closed dur-
ing a Leak Diagnosis test. The change over valve is open during all other periods of oper-
ation allowing the fuel system to “breath” through the inlet filter (similar to the full down
stroke of the current vacuum operated LDP).
DC MOTOR LDP INACTIVE -- NORMAL PURGE VALVE OPERATION
In it’s inactive state the pump motor and the change over valve of the DC Motor LDP are
not energized. When purge valve operation occurs filtered air enters the fuel system com-
pensating for engine vacuum drawing on the hydrocarbon vapors stored in the charcoal
canister.
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LEAK DIAGNOSIS TEST PRECONDITIONS
The DME only initiates a leak diagnosis test every second time the criteria are met. The cri-
teria is as follows:
• Engine OFF with ignition switched OFF.
• Engine Control Module still in active state or what is known as “follow up mode” (Main
Relay energized, control module and DME components online for extended period after
key off).
• Prior to Engine/Ignition switch OFF condition, vehicle must have been driven for a min-
imum of 20 minutes.
• Prior to minimum 20 minute drive, the vehicle must have been OFF for a minimum of 5
hours.
• Fuel Tank Capacity must be between 15 and 85%(safe approximation between 1/4 -
3/4 of a tank).
• Ambient Air Temperature between -7
OC & 35OC(20OF & 95OF )
• Altitude < 2500m(8,202 feet).
• Battery Voltage between 11.5 and 14.5 Volts
When these criteria are satisfied every second time, the ECM will start the Fuel System Leak
Diagnosis Test. The test will typically be carried out once a day i.e. once after driving to
work in the morning, when driving home in the evening, the criteria are once again met but
the test is not initiated. The following morning, the test will run again.
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