How To Test BMW Motorcycle Ignition Coils

Problems with an engine running rough or "missing" often come down to the ignition coils. The coil-on-plug or "stick" coils found on BMW motorcycles with boxer engines like the RT and GS can be a little tricky to test and diagnose because BMW does not publish specs. I also found during the making of this video that using a multimeter to test the resistance of the primary and secondary windings does not work in the way that it does for coils of other manufacturers. However, I'll show you three methods you can use to test your BMW coils.
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amzn.to/3ELqC0D (14mm thin-wall spark plug socket)

[@joepasquarello1273]

Good tip on the removal tool.

[@user-dq8uk7xk4q]

Thank you very much, you helped me a lot.. I have a 2014 s1000rr and with the help of this test I found out exactly what was wrong.. Hello from Israel

[@tinderboxarts]

Awesome--I'm glad it was helpful!

[@douglasdickson6986]

Plug removal tool are great

[@oldmoto3542]

A dynamic test of the secondary side of the coils is the best way.

[@tinderboxarts]

As I discussed in the video, though, the secondary side of these particular coils cannot be tested with a meter. You are referring to a test to see if the secondary side produces a spark, but that has limited utility. The quality or consistency of that spark if it is there can't be determined by eye. You can only determine if there is a spark at all.

[@oldmoto3542]

@@tinderboxarts You would use a oscilloscope with an inductive pick up to read the secondary side voltage.

[@tinderboxarts]

Ha! Yeah, well, not too many home mechanics or even dealer mechanics have a scope, never mind the specs to compare. Back in the 80s when I was trained, most automotive shops had a Sun or Snap-on automotive scope which could be used to compare scope patterns. I recall in school trying to memorize scope patterns for the tests. The reason those scopes fell out of favor and eventually disappeared is because the huge variety of ignition component brands and types eventually made it impossible to know what was a good pattern and what was bad pattern. The manufacturers certainly weren't publishing the info. Just knowing the peak voltage under a given condition is also no guarantee of good or bad, without additional comparison specs. I haven't seen an operating scope in an automotive or motorcycle shop in decades.

[@oldmoto3542]

I understand what you are trying to say the average person is not going to have an oscilloscope in there toolbox, I agree. I have been a mechanic for 25 years and the most accurate way to know if those coils are good or any pencil type coil is to measure dynamically on the secondary side most coils read anywhere above 8k Volts and knowing how to read the scope is important as well.
Coil saturation can be seen when using a scope as well. 👍

[@user-rz5bd4cb9f]

Out of curiosity did you try reversing the meter leads when checking the secondaries?

[@tinderboxarts]

When measuring resistance the polarity generally doesn't matter unless you have certain electronic circuitry, such as a diode, which only flow one way. But if such circuitry existed for the secondary side of this coil, the measurement really wouldn't be useful anyway since the reading might be skewed by the circuit.

[@BMWer]

There is a diode inside.

[@tinderboxarts]

Yes, I think something like that is the case.