Electrical weirdness

[Jabbah]

The misfire problem I had over new years has been "fixed". Turns out the ignition leads for two cylinders on one bank were the wrong way round. Which is odd, because that's not something that usually occurs whilst driving along a motorway.

My guess is that the garage looking at it accidentally swapped them over whilst tracking down the problem (probably caused by water or a loose connection, coil pack on the way out, magnecore leads...) even though they swear they didn't. Just want to check though that it is not possible for an electrical gremlin to change the firing order, whilst driving..?

This misfire seems to be a recurring problem now as when it was down for a service it started to misfire which was "solved" by a new tank of fuel. Then again it happens when driving in the rain and again there is no definite diagnosis. I think for peace of mind I will get a set of TVR Cerbera leads to replace the Magnecore leads and replace the coil packs too, maybe even get some proper water proof connectors for the lambda sensors as suggested by Tanguero.

[N7GTX]

The coil packs fit other cars and on them, these coils are wasted spark type. That is they fire twice in every engine cycle, instead of once as in older cars. So you get a spark on the power stroke and also on the exhaust stroke. So, if on a Cerb the ecu fires the coils the same way, it could be possible that the leads may be wrongly fitted and that the secondary spark is actually doing the firing on the power stroke?
I have been sorting mine and replaced the plugs when the manifolds were off but it still seemed to misfire. Replaced the coils as the spark on number 6 kept failing on the tester. Much better but under snap accleration there was a very slight hesitation. Replaced the leads and all is now good.
Even if you cure the electrical side there could still be an issue with an injector. Dont you just luv 'em.