I've been getting P0302 misfires for a while now, despite changing coils, plugs, valve cover, gaskets all within the past 15K-30,000 KMs. The last incident was pretty rough w/ the engine shaking uncontrollably and CEL flashing. I drove the car to the shop and left it there the same day the engine was shaking/CEL flashing. After cleaning the oil leak and replacing the valve cover + gaskets, I'm being told the car is still shaking a lot at idle. Mechanic is telling me to buy new plugs and coils (again). How do I know it's not something else, like the engine mount or fuel injectors going bad?? What else can cause so much vibration + CEL flashing???

2012 G37x

 

Got an update - the new error codes are P0302, P0304, and P0300. Misfire on Cylinder 2 / 4 / random. They also looked at engine mount/transmission mount and said it looks fine. I ordered new NGK spark plugs and they are on the way (previous ones I installed 30K km ago were Denso).

 

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