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... Further fault patterns with evaluation
Evaluation of sparking period and ignition voltage peaks at idling speed.
- Normal combustion period.
- Normal ignition voltage peak.
Ignition system is OK.
Long sparking period (1) with low ignition voltage peak (2). Indicates low compression.
Fluctuating sparking period: Indicates contamination on spark plug (shunt).
Short sparking period (1) with high ignition voltage peak.
Constant but short sparking period: indicates defective ignition lead.
| Electrode Gap | Large |
| Compression | High |
| Fuel Air Mixture | Lean |
| Electrode Temperature | Low |
| Electrode Condition | Burnt |
| Ignition Lead | Interrupted |
| Electrode Gap | Small |
| Compression | Low |
| Fuel Air Mixture | Correct |
| Electrode Temperature | High |
| Electrode Condition | New |
NO RELATED
Use the Manual With the Right Hardware
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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.