BMW X5: Engine Diagnosis

Engine Diagnosis

When attempting to diagnose driveability complaints, always consider the basics. Regardless of the level of technology employed on an engine, it still needs a few basic things to occur in order to run properly. Whether the engine is very basic or uses so-called "New Generation" technology always refer to the basic principles first.

Any engine using four-cycle spark-ignition principles must meet the same fundamental conditions to run properly. Most engine related driveability problems fall into a few basic categories:

• No Start/No Crank
• Extending cranking before engine start
• Rough Running Cold Idle
• Rough Running Warm Idle
• Rough Running Under Load
• Lack of Power
• Check Engine Light (MIL)

Fig. 1: Sectional View Of Engine

When referring to engine basics, all engines need fuel, air and spark to run. However, in order for a spark-ignition engine to run properly, a few things must be taken into consideration. The fuel, air, spark principle can be broken down further into the following categories:

• Sufficient engine compression with a leak-free combustion chamber.
• Sufficient amount of ignition voltage (spark) at the correct time.
• Proper fuel pressure and volume.
• Properly functioning fuel injection system (Engine management).
• Properly functioning air management system (Electronic throttle systems).
• Correct valve timing (VVT and VANOS).

Fig. 2: Operation Of Valvetronic

• Compression Testing
• Workshop Hints On Cylinder Leakage Testing
• Ignition System Diagnosis
• Fuel System Testing
• Fuel Volume Testing
• Fuel System - E32 With M60
• Engine Adaptation Values
• Smooth Running Measurement

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