My 1198 bmw 318i compact is only sparking on 1&3 cylinder

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Hi,

I'm Ben and -- hopefully -- I can provide some meaningful assistance.

I recommend a diagnostic scan to confirm my diagnosis of a malfunctioning coil(s).

How to Test and Replace Ignition Coil on BMW 3 Series

The following procedures apply for BMW 3 series (6-cylinders engine) 1992 - 1998 model years. To Test and Replace the Ignition Coil, do the following:

1. Remove plastic engine covers from top of engine by prying off nut covers and removing cover mounting nuts.
2. Disconnect harness connector from coil. Connect multimeter between terminal 15 (+) in connector and ground. (use a digital multimeter for the following test). See Fig.1. below BMW 3 series coil harness
3. Turn ignition on and check for battery voltage. If battery voltage is not present, check wire between terminal 15 and ignition switch. The wiring to terminal 15 (+) of the coil (via the ignition switch) is not fuse protected. Use care when testing this circuit.
4. Turn ignition off.
5. Use a multimeter to test coil primary resistance at coil terminals. (primary coil terminals: 1 (-) and 15 (+), primary coil resistance: 0.4-0 .8 ohms; secondary coil terminal and resistance: NA).
6. Remove coil and inspect coil housing for hairline cracks or leaking casting material . A leaky ignition coil may indicate a faulty engine control module (ECM). Check ECM before installing a new coil.
7. When replacing ignition coils, ensure that the replacement coil(s) are from the same manufacturer containing the same part code numbers. If individual coils with the correct specifications are not available, all coils should be replaced.