BMW tech articles

[shogun]

for various built years
http://www.germanpartsonline.com/bmw-articles/

for example:

rough idle and/or a misfire under heavy engine load may be received on E36 and E34 (M50 equipped) vehicles due to a break on the secondary side of the ignition coils. These coils were produced by the vendor named "May und Christ."Correction: If your vehicle encounters the above problem, proceed as follows:

With the cylinder head cover removed (exposing the tops of the ignition coils) identify the vendor:

Vendor Identification

•"May und Christ" = ZUNDSPULE
•Bosch = Bosch
Identify the production year and month of the "May und Christ" coils located directly above the word ZUNDSPULE, i.e., 91 M 06 (year = 91, month = 06 (June) ). Coils with a production date code prior to 91 M 01 (January 1991) may have a break on the secondary side which can be diagnosed by removing the ignition coil from the engine. With the coil removed, twist and pull the spark plug connector off the coil and examine the connection.

A poor connection may be seen as green corrosion or (a) piece(s) of plastic found in the ignition coil socket which has broken off the spark plug connector. In this case, the coil must be replaced.

Parts Information: Replace the coils with part number 12 13 19 066 468. (Note part number might be superseded, use the latest part number)