My wife's 2002 I35 with the 3.5L V6 with 143K on the odometer started misfiring on cylinder 5 on Monday. I replaced all of the spark plugs and the ignition coil on cylinder 5 last night. Then when I started it up, it was worse. It was now misfiring on cylinder 6 (thankfully that is in the front and easy to get to). I swapped the ignition coils between cylinder 6 and cylinder 2 to see if it was the coil. Cylinder 2 started misfiring which means it is the coil and will be replaced today.

I thought it was odd that suddenly after I put everything back together a different coil failed.

Is this just a coincidence or is there another issue that I may be missing?

 

Did you get coils from the dealer?if not issues are going to happen

 

I bought the Denso Coil 6734023, which is the OEM coil.