12 13 ... Ignition Coil Faults

Evaluation of ignition voltage peaks and attenuation process at idling speed:

1. Beginning of attenuation processes with normal peaks upwards and downwards.
2. Beginning of attenuation processes strongly shortened. Ignition coil is defective.
3. Absence of initial downwards attenuation. Ignition coil is defective.
   NOTE: Higher ignition voltage peak is not always available.
Fig 1: Evaluation Of Ignition Voltage Peaks & Attenuation Process
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Evaluation of sparking voltage line at idling speed:

1. Normal combustion period.
2. Normal attenuations to sparking voltage line. Ignition coil is OK.
Fig 2: Evaluation Of Sparking Voltage - Normal Combustion Period
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1. Shorter sparking period.
2. Attenuation to sparking voltage line is only slight. Ignition coil is defective.
Fig 3: Evaluation Of Sparking Voltage - Shorter Period
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1. Much shorter sparking period.
2. Attenuations to sparking voltage line absent. Ignition coil is defective.
Fig 4: Evaluation Of Sparking Voltage - Much Shorter Period
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No sparking voltage line. Ignition coil is defective.

Fig 5: Evaluation Of Sparking Voltage - No Sparking Voltage Line

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Evaluation of combustion voltage line at raised engine speeds approx. 1500 Min (1):

1. Normal combustion period.
2. Normal attenuations to sparking voltage line. Ignition coil is OK.
Fig 6: Evaluation Of Combustion Voltage Line - Normal Combustion Period
Courtesy of BMW OF NORTH AMERICA, INC.

1. Shorter sparking period.
2. Attenuation to sparking voltage line is only slight. Ignition coil is defective.
Fig 7: Evaluation Of Combustion Voltage Line - Shorter Sparking Period
Courtesy of BMW OF NORTH AMERICA, INC.

1. Normal combustion period.
2. Attenuations to sparking voltage line absent. Ignition coil is defective.
Fig 8: Evaluation Of Combustion Voltage Line - Normal Combustion Period
Courtesy of BMW OF NORTH AMERICA, INC.