BMW X5: 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 the event of HPI limp-home mode, turbocharging is deactivated by an opening of the wastegate valves.
Causes of HPI limp-home mode can be:
- Implausible high-pressure sensor values
- Failure of the fuel-supply control valve
- Leakage in the high-pressure system
- Failure of the high-pressure pump
- Failure of the high-pressure sensor
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Fig. 56: Identifying Limp-Home Mode Diagram
Fuel System Safety
Working on this fuel system is only permitted after the engine has cooled down. The coolant temperature must not exceed 40ºC. This must be observed without fail because otherwise there is a danger of fuel sprayback on account of the residual pressure in the high-pressure system.
When working on the high-pressure fuel system, take particular care to ensure conditions of absolute cleanliness and follow the work sequences described in the repair instructions. Even the tiniest contaminant's and damage to the screw connections on the high-pressure lines can cause leaks.
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Fig. 57: Identifying Fuel System Safety Label
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Fig. 58: Identifying High-Pressure Fuel Lines
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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
Piezo Element
The movement of the nozzle needle in the injector is generated no longer by a
solenoid coil but rather by a
piezo-element.
A piezo-element is an electromechanical converter, i.e. it consists of a ce
Ignition Management
Most of the ignition system components have remained the same for all NG6
engines for 2007. There are some
minor changes to the ignition coils that apply to all versions. The coils have
been optimiz
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Drawing Off, Evacuating And Filling A/C System (R 134A)
WARNING: Refrigerant circuit is under high pressure!
Repair work may only be carried out on a DEPRESSURIZED refrigerant
circuit!
Avoid contact with refrigerant and refrigerant oil.
Follow safety instructions for handling refrigerant R 134a.
Follow safety instructions for handling refrigerant oil.
I
Instructions On Starting Aid
Do not start the engine with help of starting sprays.
Preparation:
Conform with the following when starting engine with starting cable.
Ensure that jump lead wires are to appropriate cross-section size.
Only use fuse-protected jump leads.
Check whether the current supplying battery has 12 V volt
