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

WARNING: This page is about a different car, the 2002 BMW M Roadster, 2002 BMW M Coupe, 2001 BMW M Roadster, and 2001 BMW M Coupe. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Identifying Signal Wave Form

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Secondary voltage patterns, beside one another:

Fig 2: Identifying Secondary voltage Patterns

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Evaluation of ignition voltage peaks at idle speed (this example shows an engine with 4 cylinders).

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.
In event of greater differences, refer to Further Fault Patterns With Evaluation .

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

Fig 3: Identifying Ignition Voltage Peaks

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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

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Secondary voltage diagrams, consecutive:

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.

Fig 5: Identifying Secondary Voltage Diagrams, Consecutive

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