Intermittent Misfire

[Bloater]

Hi

Over the last few months my 960 has developed an occasional misfire; suspect it's running on 5. The misfire is really sporadic and doesn't seem to be associated with any specific conditions.

I have had a look at the coil packs and think one of them may be the problem; they're all looking their age (heat tarnished), and a couple have hairline cracks in their exterior. Unfortunately though, as I never know when it's going to happen, I don't get chance to pop the bonnet and unplug individual packs to check them.

I was therefore wondering if anyone has any suggestions on how I could confirm a failure before replacing any and, also, dose anyone know if coil packs can fail intermittently or do they normally just stop working.

Any thoughts would be really appreciated.

Thanks