Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Does that abnormal waveform come up every six firing events? If so, I think you're looking at a shorted secondary somewhere. Water in the plug boot will do this. A badly blown head gasket (with coolant across the plug gap) will, too.
I’m not sure. I’m going to hook up a second channel on my modis to determine which cylinder it is. I thought it was a bad wire. Tried moving it to different cylinder and do drop test but it’s too hard to pull the wires while it running. I’ll try tomorrow. Thanks for the reply
A plug wire that is not seated properly can do that, too.
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