Using Ignition Coil Current Patterns for Diagnosis
Current waveform taken off PCM control wire to ignition coil, 01 Merc Grand Marquis 4.6 V8 67k miles, original plugs, idle speed multi firing mode.
New plug dropped coil load somewhat.
Added a plug wire between plug and coil to view changes in secondary, here is a plug with a closed gap to simulate a shorted plug and this is the result in the current waveform.
Here is a wide gap (.080) results.
I cut the side electrode off the plug to get this result.
Here I just unplugged an injector, nothing seemed to change the initial ramp, only the last two firings. Interesting.