BMW X5: Turbocharger Diagnosis
There are three "Golden Rules" to adhere to when diagnosing concerns on the N54 engine:
1. When diagnosing cases of smoke from the exhaust, it is important to avoid unnecessary replacement of the turbochargers. Smoke can be caused by oil consumption such as the crankcase ventilation system.
Always evaluate the crankcase venting system completely before condemning any turbocharger components. Also, any engine is also subject to the usual causes such as valve guide wear or piston ring issues as on non-turbocharged engines.
2. Turbocharger damage is usually caused by -
- Insufficient lubrication and subsequent bearing and seal failure.
- Foreign bodies can damage the turbine and/or impeller.
- Oil contamination
- Restricted air filter
- Ensure that all duct work connections are tight and "leak-free". This situation can also result in engine noise.
3. Do not make any alterations or modifications to the turbocharger. Do not make any adjustments to the boost control linkage or any part of the turbocharger. Higher than normal boost pressure may have adverse and detrimental effects on the engine. Any modification will cause the engine management to enter in the "limp-home" program and will reduce performance and engine reliability.
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Fig. 44: Identifying Modifications To Turbochargers
NOTE: No Modifications to the turbochargers are permitted.
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Measure and record the following values for the listed components under the indicated operating:
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Fig. 45: Identifying Diagnosis Function Table
Hot-Film Air Mass Meter
Some new NG6 engines use a digital HFM. The output of the sensor is converted to a digital signal. This eliminates the need for signal conversion in the ECM. The signal corresponds proportionally to changes in air mass. The N54 engine uses a virtual HFM. The signal is "calculated" in the ECM from various parameters such as engine speed, intake air temperature, throttle position etc.
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Fig. 46: Identifying Hot-Film Air Mass Meter Diagram (1 Of 2)
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Fig. 47: Identifying Hot-Film Air Mass Meter Diagram (2 Of 2)
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Fig. 48: Identifying BMW Measuring Oscilloscope Display Screen
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Fig. 49: Identifying Oscilloscope Settings Table
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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
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
SEE MORE:
Fuel Volume Testing
Some driveability concerns are related to incorrect fuel volume. Vehicles
with lack of power complaints and
mixture related fault codes may have insufficient fuel volume supplied to the
fuel injection system. These
vehicles may actually pass a fuel pressure test.
Fuel volume issues can be caused
Opening Plug Housings And Removing Contacts Of Different Plug
Systems
Special tools required:
61 0 300
61 0 400
61 1 150
Abbreviations and what they mean:
ABBREVIATIONS MEANINGS
Ultrasonic-welded connectors:
Ultrasonic-welded connectors (1) can be identified by the welds (2) on their
longitudinal side.
The contacts of these connectors cannot be replaced. Repla
