N42 / N62:
WARNING: This page is about a different car, the 2005 BMW 645Ci and 2004 BMW 645Ci. However, it is still accessible from the selected car via links, so may be relevant.
The following normal oscillogram is applicable to engines with multiple-spark ignition from the production date of April 2001:
Depending on the engine temperature/speed, some ignition voltage peaks can occur before the typical ignition voltage curve.
These peaks do not play any role for diagnostics.
The last ignition voltage peak (1) before the ignition voltage curve is the decisive factor for the test.
NOTE:
The indication of the ignition voltage needle is approx. 20-25 % lower than the real value.
The uniformity of all cylinders to each other is more important than the height of ignition voltage peaks.
Differences of 3000 to 4000 volts are permitted.