12 13... Normal oscillogram (M, S, W engines only)

WARNING: This page is about a different variant/trim than selected.

Fig 1: Identifying Normal Oscillogram Readings

Courtesy of BMW OF NORTH AMERICA, INC.

Secondary voltage patterns, beside one another: Evaluation of ignition voltage peaks at idle speed (this example shows an engine with 4 cylinders).

Fig 2: Secondary Voltage Patterns

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: The display of ignition voltage spikes is approx. 20-25% lower than the real value.
The uniformity of all cylinders to each other is more important than the height of ignition voltage peaks. Differences of 3000... 4000 V are permitted.

Evaluation of ignition voltage peaks at increased speed of approx. 2000 RPM (this example shows an engine with 4 cylinders).

Fig 3: Identifying Evaluation Of Ignition Voltage Peaks At Increased Speed

Courtesy of BMW OF NORTH AMERICA, INC.

Secondary voltage diagrams, superimposed:

Evaluation of combustion characteristics curve and decay characteristics at idle speed (this example shows a 4 -cylinder engine).

Fig 4: Identifying Secondary Voltage Diagrams Superimposed

Courtesy of BMW OF NORTH AMERICA, INC.

Secondary voltage diagrams, consecutive:

Fig 5: Identifying Secondary Voltage Diagrams, Consecutive

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: Only the major differences in the ignition voltage patterns are revealed by this method of comparison.

The identified fault must be allocated to the relevant cylinder using the secondary voltage representation forms next to/on top of each other.