I have a 06 V50 with the T5 and R design options and 298,345 miles on the clock. I’ve got a head scratcher going on. It started with a CE code for random Mis on 2 & 4. Switched the coil packs and the Mis stayed on 2 & 4. Bought new plugs set the gaps and it was good as new for about 50-60 miles then boom running like crap again. Read the codes again and now 2,4 & 5 are missing. Should note 5 is the Coil pack I switched out when diagnosing the miss. Trying to avoid taking it to the shop but I don’t really know where to go from here. Any suggestions would be appreciated.

 

I'd switch the coil packs for 3 and 5 just for giggles, just to see if the "new" misfire is just a coil pack.

I'd suspect injectors, and would try swapping them around to see if the problem follows. I'd also suggest doing a compression test - with that many miles, it wouldn't be unheard of for the problem to be relating to rings (affecting compression).

Also, check the plugs for any signs of oil (maybe the new plugs fixed the problem until they were oil-soaked as well).