BMW X5: 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 by faulty fuel pumps, fuel pressure regulators, clogged or restricted fuel filters and/or fuel lines.
If these driveability concerns are present, then a fuel volume test should be performed. A fuel volume test measures the amount of fuel delivered in a specific time frame.
The fuel pump is activated during this test using the proper test leads to ensure no arcing sparks are present. The fuel feed line is directed to a non-breakable (fuel-proof plastic) measuring can that has graduations for measurement.
.png)
Fig. 15: Checking Fuel Volume Using Measuring Can
A general specification for fuel volume would be approximately one liter in 30 seconds.
Residual Pressure
Fuel injection systems require a residual pressure to present after the engine is switched off. This allows the engine to start immediately after the vehicle has been parked.
If the residual fuel pressure diminishes after the vehicle has been shut off. Upon restart, there will be an extended cranking period before engine start. This is due to the fuel pump attempting to supply enough fuel for startup.
When the fuel system is at rest, there a three components which allow the fuel system to retain sufficient residual pressure. These items are, the fuel pump check valve, the fuel pressure regulator and the fuel injectors.
READ NEXT:
Fuel System - E32 With M60
Fig. 16: Identifying Fuel System - E32 With M60 Components
If any of these items are leaking and fail to hold pressure in the fuel rail,
the vehicle will be difficult to start.
The cranking time wi
Engine Adaptation Values
Engine adaptation values can be broken down into two categories:
Additive Mixture Adaptation - additive adaptation refers to "long term
fuel trim". These adaptation are
made by the ECM (DME) at i
Smooth Running Measurement
The DISplus/GT-1 are helpful in pinpointing the cause of an engine misfire.
Once the short test is completed,
the fault memory of the ECM can be read out to determine which cylinder or
cylinders hav
SEE MORE:
Lower tailgate - Tailgate
Lower tailgate
Opening
General information
When open, the lower tailgate can support loads
of up to 550 lbs/250 kg.
Functional requirement
The upper tailgate must be open.
From the outside
Without Comfort Access:
Press the button on the lower
tailgate
and fold the lower tailgate down.
With Comfort
Ignition Coil
NOTES ON CHECKING IGNITION SYSTEM
Troubleshooting -> Fault in fuel injection system
-> Spark plug faults
-> Ignition coil faults
-> Further fault patterns with evaluation
-> Additional fault notes for troubleshooting.
Oscillograms -> Normal oscillogram
-> Oscillograms of ignitio
