BMW X5 2005 E53 M54 Engine Owner's Manual

21
M54engMS43/ST039/3/17/00
LEAK DIAGNOSIS TEST
PHASE 1 - REFERENCE MEASUREMENT
The ECM activates the pump motor. The pump pulls air from the filtered air inlet and pass-
es it through a precise 0.5mm reference orifice in the pump assembly.
The ECM simultaneously monitors the pump motor current flow . The motor current raises
quickly and levels off (stabilizes) due to the orifice restriction. The ECM stores the stabilized
amperage value in memory. The stored amperage value is the electrical equivalent of a 0.5
mm (0.020”) leak.

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M54engMS43/ST039/3/17/00
PHASE 2 - LEAK DETECTION
The ECM energizes the Change Over Valve allowing the pressurized air to enter the fuel sys-
tem through the Charcoal Canister, The ECM monitors the current flow and compares it
with the stored reference measurement over a duration of time.
Once the test is concluded, the ECM stops the pump motor and immediately de-energizes
the change over valve. This allows the stored pressure to vent thorough the charcoal can-
ister trapping hydrocarbon vapor and venting air to atmosphere through the filter.

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M54engMS43/ST039/3/17/00
TEST RESULTS
The time duration varies between 45 & 270 seconds depending on the resulting leak diag-
nosis test results (developed tank pressure “amperage” / within a specific time period).
However the chart below depicts the logic used to determine fuel system leaks.

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M54engMS43/ST036/6/2000
MS 43 CARRY OVER FUNCTIONS
INPUT FUNCTIONS
BOSCH OXYGEN SENSORS
The MS43.0 system uses Bosch LSH 25 oxygen sensors that function basically the same
as previously used (in Bosch systems). The voltage range is between 0 - 800 mV.
The location remains the same with the pre-cat sensors are mounted on top of the exhaust
manifolds. The catalysts are now integral with the exhaust manifolds (further detailed in the
M52 TU engine section).
PRE 02 SENSOR POST 02 SEN-
SOR
POST-CATALYST
SENSORS

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M54engMS43/ST036/6/20000
OXYGEN SENSOR SIGNAL INFLUENCE ON INJECTOR “OPEN” TIME
The ECM monitors the:
• Amplitude of the signal (highest voltage or range sensor is producing)
• Switching time of the signal (how fast from lean to rich)
• Frequency of complete cycles (how many within a period of time)
These characteristics provide info to the ECM that reflect the overall condition of the sen-
sor.
POST CATALYTIC CONVERTER SENSOR SIGNAL
The post catalyst O2 sensors monitor the efficiency of the catalyst as a requirement of OBD
II. This signal also provides feedback of the pre-catalyst sensors efficiency and can cause
the ECM to “trim” the ms injection time to correct for slight deviations.
• If the catalyst is operating efficiently, most of the remaining oxygen in the exhaust gas
is burned (lack of O2 - “constant lean signal”).
The sensor signal fluctuates slightly in the higher end of the voltage scale.
• If the post sensor shows excessive fluctuations
(which echo the scope pattern of the pre
sensor), this indicates that the catalytic converter is not functioning correctly and cannot
consume the O2 (fault set).
• If the post sensor fluctuations move out of the normal voltage “window”, this indicates
that the pre sensor is not performing properly due toslight
deterioration. These systems
can also “trim” the ms injection time to compensate for this.
The constantly changing oxygen sensor input to the ECM is needed to correct the ms
injection time to ensure that the ideal air/fuel ratio is maintained.

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M54engMS43/ST036/6/2000
CAMSHAFT SENSOR
-INTAKE AND EXHAUST CAMSHAFTS
The "static" Hall sensors are used so that the camshaft positions are recognized once igni-
tion is “on” - even before the engine is started.
The function of the intake cam sensor:
• Cylinder bank detection for preliminary injection
• Synchronization
• Engine speed sensor (if crankshaft speed sensor fails)
• Position control of the intake cam (VANOS)
The exhaust cam sensor is used for position control of the exhaust cam (VANOS)
If these sensors fail there are no substitute values, the system will operate in the failsafe
mode with no VANOS adjustment. The engine will still operate, but torque reduction will be
noticeable.
NOTE: Use caution on repairs as not to bend the impulse wheels
KL 15 KL 15
MS42.0
SOLENOID
OIL TEMP.
SENSOR TWO POSITION PISTON HOUSING
WITH INTERNAL/EXTERNAL
HELICAL GEAR CUP TWO POSITION PISTON
HOUSING WITH
INTERNAL/EXTERNAL
HELICAL GEAR CUP
ENGINE
OIL SUPPLY VENT VENT
SOLENOID
SENSOR SENSOR
MS42
ECM
EXHAUST
INTAKE
MS42.0
ECM
MS 43.0
MS 43.0
MS 43.0

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M54engMS43/ST036/6/20000
CRANKSHAFT SENSOR
The crankshaft sensor is a dynamic Hall-effect sensor (mounted through the engine block),
the signal is sent the moment the crankshaft begins to rotate.
The pulse wheel is mounted directly to the crankshaft as seen on previous models.
____________________________________________________________________
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MS 43.0
SMOOTH RUNNING ENGINE
NOTE SQUARE WAVEENGINE MISFIRE DETECTED

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M54engMS43/ST036/6/2000
MISFIRE DETECTION
As part of the CARB/OBD regulations the engine control module must determine if misfire
is occurring and also identify the specific cylinder(s) and the severity of the misfire event,
and whether it is emissions relevant or catalyst damaging. In order to accomplish these
tasks the control module monitors the crankshaft for acceleration losses during firing seg-
ments of each cylinder based on firing order.
Misfire Detection Example: M54 (6 Cyl.) with Siemens System
The misfire/engine roughness calculation is derived from the differences in the period dura-
tion (T) of individual increment gear segments. Each segment period consist of an angular
range of 120° crank angle that starts 78° before Top Dead Center (TDC).
If the expected period duration is greater than the permissible value a misfire fault for the
particular cylinder is stored in the fault memory of the ECM. Depending on the level of mis-
fire rate measured the control unit will illuminate the "Service Engine Soon" light, may cut-
off fuel to the particular cylinder and may switch lambda operation to open-loop. All mis-
fire faults are weighted to determine if the misfire is emissions relevant or catalyst damag-
ing.
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M54engMS43/ST036/6/20000
EMISSIONS RELEVANT:
During an interval of 1000 crankshaft revolutions
the misfire events of all cylinders are
added and if the sum is greater than a predetermined value a fault will be set identifying the
particular cylinder(s). The “Service Engine Soon” light will be illuminated during and after
the second cycle if the fault is again present.
CATALYST DAMAGING:
During an interval of 200 crankshaft revolutions
the misfire events of all cylinders are added
and if the sum is greater than a predetermined value a fault will be set identifying the par-
ticular cylinders(s). The “Service Engine Soon” lamp:
• On vehicles with a Siemens Control Module (M54 engines) - the lamp will immediately go
to a steady illumination since fuel to the injector(s) is removed. Fuel cut-off to the cylin-
der will resume after several (
>>7) periods of decel if crankshaft sensor adaptation is suc-
cessfully completed or the engine is shut-off and restarted.
In each case the number of misfire events permitted is dependent on engine speed, load
and temperature map.
The process of misfire detection continues well after the diagnostic drive cycle requirements
have been completed. Misfire detection is an on-going monitoring process
that is only dis-
continued under certain conditions.
Misfire detection is only disabled under the following conditions:
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___________________________________________________________________
___________________________________________________________________
REQUIREMENTSSTATUS/CONDITION
Engine Speed< 512 RPM
Engine LoadVarying/Unstable
Throttle AngleVarying/Unstable
TimingTiming retard request active (i.e. knock
control - ASC, AGS)
Engine Start-upUp to 5 seconds after start-up
A/CUp to 0.5 seconds after A/C activation
Decel fuel cut-offActive
Rough road recognitionActive
ASC ControlActive

30
M54engMS43/ST036/6/2000







  




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OBD II - Misfire Faults