How to test for coil problems 95 525i m50?

[Russell]

How do you test for existing coil problems on a M50 engine? I suspect I have one or more "tired" coils. No real apparent problems. I just want to be able to know their condition. For that matter, all of the electical system. Even so, the plugs have almost 29,000 on them and will be changed soon.

TIA

[danzee]

Russell,
I don't know if anyone else has better information, but I know of no simple way to check the coils without High Voltage instrumentation.
In addition, failure would be most often expected when the coil got hot, so you would need a way to look at the coils at temperature. The best I can think of is to make a resistance measurement (ohmmeter) of the primary on all the coils after they have gotten hot. If one were to be substantially different from the others it might be a concern. Having said that, I must tell you that coil problems are rare and I wouldn't worry about them unless there were performance symptoms.
Also, I have found with the M50TU engine that NGK plugs last me 50,000+ miles with excellent service.
(FWIW I designed CD ignition systems back in the late sixties)
Dan

[RobPatt]

just wondering.... -Rob.


Russell,
I don't know if anyone else has better information, but I know of no simple way to check the coils without High Voltage instrumentation.
In addition, failure would be most often expected when the coil got hot, so you would need a way to look at the coils at temperature. The best I can think of is to make a resistance measurement (ohmmeter) of the primary on all the coils after they have gotten hot. If one were to be substantially different from the others it might be a concern. Having said that, I must tell you that coil problems are rare and I wouldn't worry about them unless there were performance symptoms.
Also, I have found with the M50TU engine that NGK plugs last me 50,000+ miles with excellent service.
(FWIW I designed CD ignition systems back in the late sixties)
Dan

[ryan roopnarine]

i wonder if you could head off problems (if there really isn't a coil problem) by checking the coil boots with a magnifying glass. replacing those isn't too expensive. you've verified that none of the coils has any traces of oil seeping from it?

[Bill R.]

output on them is with a graphing oscilloscope, that way you get a waveform for each coil and can compare output. And yes it will damage the ecu if a coil goes bad and isn't changed .