https://www.harborfreight.com/In-Line-Spark-Checker-63590.html


I use this it’s pretty easy.

There’s other ways by taking the plug out and then grounding it near the chassis to see a spark. I always get shocked so I don’t like that method. Swap a coil from a working side and see if the miss changes to the new side

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1993 e300
1995 e320
1994 e320
2006 s500 4matic
2004 Jeep wj overland
2001 Ducati 748
2004 Honda shadow aero