Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
12 13 ... Normal oscillogram (M, S, W engines only)
Secondary voltage patterns, beside one another:
Evaluation of ignition voltage peaks at idle speed (this example shows an engine with 4 cylinders).
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).
W, superimposed:
Evaluation of combustion characteristics curve and decay characteristics at idle speed (this example shows a 4-cylinder engine).
Secondary voltage diagrams, consecutive:
The identified fault must be allocated to the relevant cylinder using the secondary voltage representation forms next to/on top of each other.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.