BMW X5: N52KP And N51 Fuel System
The N52KP and N51 engine continue to use the conventional "manifold injection" system carried over from the N52. The fuel supply components are also carried over with regard to the EKP module, fuel pump etc.
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Fig. 50: Identifying Fuel Supply System
N54 Engine
The N54 engine uses the new High Precision Injection (HPI) system. The HPI system is a "direct" fuel injection system which represents the second generation "DI" system from BMW. The first generation was on the N73 engine from 2003.
The N73 engine used a "wall guided" method of injection which used a recess in the piston to aid in mixture formation. The HPI system on the N54 uses a "spray guided" process which allows the mixture to form and ignite without the aid of any "walls" (i.e piston, cylinder wall etc.).
The spray guided system allows for more efficiency by cooling the cylinder charge without excessive cooling of the associated engine components. The wall guided system cools the piston crown which reduces thermal efficiency.
The HPI system also uses the new "piezo-electric" fuel injectors which are a vital components of the spray guided process. These new injectors open in an outward direction, which forms a precise tapered spray pattern.
With the aid of high system pressure (200 bar), the HPI system is now capable of providing new levels of efficiency which were not achievable with previous manifold injection systems.
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Fig. 51: Identifying Manifold Injection Systems
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Fig. 52: Identifying HPI Function Systems
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HPI Function
The fuel is delivered from the fuel tank by the electric fuel pump via the
feed line (5) at an "feed" pressure of 5
bar to the high pressure pump. The feed pressure is monitored by the
low-pressure
Limp-Home Mode
If a fault is diagnosed in the system, such as e.g. failure of the
high-pressure sensor, the fuel-supply control
valve is de-energized; the fuel then flows via a so-called bypass into the rail.
In t
Piezo Fuel Injectors
It is the outward-opening piezo-injector that renders possible spray-directed
direct injection and thus the overall
innovations of the N54 engine. Due to the fact that only this component ensures
th
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Replacing Both Timing Chains (N62/N62TU)
Special tools required:
11 2 001
11 2 002
11 2 003
11 2 007
Necessary preliminary tasks:
Remove lower timing case cover.
Remove timing chain (1).
Remove timing chain (5).
Release screws (7).
Remove guide rails (3 and 6).
Remove tensioning rails (2 and 4).
Installation:
Maintain tension o
Load Control
Load control of the N54 engine is effected by means of the throttle valve and
the waste gate valves.
The throttle valve is the primary component in this process. The wastegate
valves are actuated to bring about a
fine tuning of the boost pressure. At full load the throttle valve is completely
op
