Spark-Plug Faults

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.

Evaluation of sparking period at idling speed.

Normal ignition voltage peak Spark plug is OK.
Low ignition voltage peak Small electrode gap.
High ignition voltage peak Large electrode gap.

Fig 1: Evaluation Of Sparking Period During Idling Period

Courtesy of BMW OF NORTH AMERICA, INC.

Evaluation of sparking period at idling speed:

Normal combustion period:
- Spark plug is OK

Long combustion period:

Small electrode gap.

Fig 3: Evaluation Of Sparking Period - Long Combustion Period

Courtesy of BMW OF NORTH AMERICA, INC.

Short sparking period:

Large electrode gap.

Fig 4: Evaluation Of Sparking Period - Short Sparking Period

Courtesy of BMW OF NORTH AMERICA, INC.