1997 UK car with standard and original (I think) ignition system components - except plugs of course. 120000 miles

I have done a few mods and use a road dyno to test the outcome of these. I can only get a signal from 1 plug lead with the inductive pick up and on about 3 runs recently I have had drop out round about 5000rpm.

The road dyno instructions say this is sometimes due to weak HT voltage and points the finger at the coil. What are the symptoms of a duff coil pack and how long do the last in general ?

And when should HT leads be replaced as a matter of course ?


On a track on Sunday I had misfire with WOT in 3rd after 1 particular corner, I was down to just under 1/4 of a tank and thought this was probably down to fuel surge as it was quite a long corner, but misfire was again at about 5000rpm each time, but of course it was after the same corner and in pretty much the same place on the track so ?


Thanks for any advice / experiences.