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)
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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).
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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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Compression Testing
In order for an engine to run smoothly and efficiently, the combustion
chamber must be free of leakage. An
engine with low compression in one or more cylinders is inefficient and will run
rough or l
Workshop Hints On Cylinder Leakage Testing
When performing cylinder leakage tests, the following tips might be helpful:
Remove all spark plugs to allow easier rotation of the engine. (If this test is
done after a compression test, the
plugs s
Ignition System Diagnosis
The ignition system on modern BMW engines consist of one ignition coil per
cylinder. This arrangement is
known as RZV, or Direct Stationary Ignition. The ignition coil receives fused
power usually f
SEE MORE:
Leak-Testing Evaporator
Special tools required:
64 5 104
64 5 108
Necessary preliminary tasks:
Remove expansion valve.
Replace sealing rings (1) and coat with refrigerant oil.
Fig. 90: Identifying Sealing Rings
Mount special tool 64 5 108 and retainer (1) with screws of expansion valve.
Tightening torque.
Fig. 9
Removing And Installing / Replacing Control Unit For Transfer Box (ATC
700)
IMPORTANT: Read and comply with notes on protection against
electrostatic damage (ESD
protection).
Replacement:
Before and after replacement, execute the "Repair" service function with
the BMW diagnosis system.
Necessary preliminary tasks:
Raise luggage compartment floor trim
Release screws
