5 Series E34 525td (M51) TOUR
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With the use of the diesel particulate filter, the Digital Diesel Electronics (DDE) require the following additional
components:
•
Throttle valve
A throttle valve restricts the intake air flow under certain operating conditions. In combination with 1 or 2
post-injection phases, this brings about an increase in the exhaust temperature (regeneration of diesel
particulate filter).
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•
Exhaust backpressure sensor upstream of diesel particulate filter, exhaust temperature sensor upstream
of catalytic converter and exhaust temperature upstream of diesel particulate filter
The exhaust backpressure sensor is used to calculate the charge level of the diesel particulate filter when
the vehicle is being driven. If the diesel particulate filter has stored too large a quantity of soot particulates,
generation is initiated.
As another variable, the exhaust temperature upstream of the diesel particulate filter is measured.
Measurement of the exhaust backpressure by the exhaust backpressure sensor is insufficient on its own
(dependence on load).
From the two signals, the DDE calculates the precise charge level of the diesel particulate filter.
The exhaust temperature sensor upstream of the catalytic converter monitors the exhaust temperature
upstream of the oxidation catalytic converter. The diesel particulate filter cannot be regenerated until the
exhaust reaches a temperature of approx. 350
°
C.
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Gastight swirl flaps
The M57TU has completely gastight swirl flaps (electrically operated on E46, otherwise vacuum-operated).
This means that there is no leakage past the swirl flaps at lower engine loads, thereby increasing the
degree of swirl. In addition, a wide range of intermediate swirl-flap settings can be achieved by electrical
operation of the flaps.
System functions
Despite the component tolerances and lifetime-effects on components (e.g. wear), the following points must be
noted: The exhaust emission limits must be achieved with a sufficiently large safety margin. Major fluctuations
relevant to emissions are principally expected for the following components:
-
Injectors
-
Mass air flow sensor
-
Rail pressure sensor
Compensation must be made for the tolerances of the components and the influences on components over the
running time. The following system functions are provided for the DDE (digital diesel electronics) for compensation:
-
Injection quantity compensation
-
Zero-quantity adaptation
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Mean quantity adaptation
-
Regeneration of diesel particulate filter (M57TU in E60/E61 only)
Injection quantity compensation
Injection quantity compensation is the definition of correction values for the pre-injection and main injection of an
injector. Injection quantity compensation is carried out at the end of the production process.
Tolerances during production of the injectors mean that the actual quantity of fuel injected will differ slightly from
the quantity of fuel calculated. After production, this difference is determined for each injector at various
SBT EURO 4 exhaust emission regulations and E-OBD for M47TU diesel engines M47TU, M5
BMW AG - TIS
23.01.2013 11:42
Issue status (12/2007) Valid only until next DVD is issued
Copyright
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