Hi from Dunedin New Zealand. I ride a 2002 ST4s that was bought new in 2008 and has now travelled 8800km.I have fitted a power commander and carbon mufflers and done some minor alterations to the air box. Spent some time setting up suspension and am generally happy with the results. There has been an intermittant problem almost from new and that is the bike sometimes starts on one cylinder and if left idling will usually pick up the second cylinder. Recently on a trip it dropped a cylinder and I managed to make it home on one cyl. Since then have started checking to try and locate cause. I noticed that when cranking the vertical injector will give one charge then nothing. Have had the ECU, an IAW 59m checked by Avanti and they said it tested ok but suggested that the immobilizer may have failed. We agreed to reflash the ECU and remove the immo function. Refitted to bike and took out the immo, tried to start started briefly on one cylinder and not a kick since. Had an additional battery connected to make sure there was sufficient voltage. I am starting to run out of ideas, can anyone offer any suggestions.
Try taking the leeds off and swapping the ignition coils over . If your problems change to the other cylinder then you have a coil failure . That would be my bet .Ignition System - Ducati Up North
Sorry I don't know air gap spec, just think I may have read about this causing a miss-fire on a forum some time in the past.