Car - AE71

motor / part in question - 20v silvertop with adaptronic ECU

problem - Engine only running on 2 cylinders

occurs/started when (if applicable)- car has been sitting in the shed for awhile, started it about a month ago and it was running fine. Started it today to get the car ready for wakefield on Wednesday and it's only running on 2 cylinders now. Swapped/moved around all spark plugs and coilpacks and all are working. Coilpacks are receiving all signals from ECU. Cylinders 3 and 4 are not firing. Spark plugs are black in those 2 cylinders. Back fires out of the inlet when trying to start. Can only guess fuel is working as it's pouring out of the exhaust.

No idea what's happening. I've left the spark plugs out tonight to air it out as maybe it was over fuelled. Not sure.

Any ideas guys? Really keen for this to be working for wakefield!