Defects of ignition coils (BMW X5 E53)

Analysis of maximum values of breakdown voltage and the process of oscillation damping for the crankshaft rotation frequency in idle mode (Fig. 3.45).

• 1 - the beginning of the attenuation process with normal upper and lower oscillation amplitudes;
• 2 - a strong reduction in the amplitude of oscillations at the beginning of the attenuation process (top arrow), the ignition coil is faulty;
• 3 - the lower amplitude of the beginning of the oscillation damping process is absent (bottom arrow), the coil is faulty.

Note: Increased amplitude (3) of oscillations of the maximum value of breakdown voltage is not always observed.

Analysis of the voltage curve on the spark plug electrodes at idle speed:

• the ignition coil is working properly (fig. 3.46,a).

• the ignition coil is faulty (fig. 3.46.6).

• the ignition coil is faulty (fig. 3.46,c).

• the ignition coil is faulty (fig. 3.46. g). There are no voltage fluctuations on the spark plug electrodes.

Analysis of the spark plug electrode voltage curve for crankshaft speed at partial loads (1500 min⁻¹):

• the ignition coil is working properly (fig. 3.47,a).

• the ignition coil is faulty (fig. 3.47.6).

• the ignition coil is faulty (fig. 3.47,c).