I own a sapphire RS Cosworth 4wd converted to 2wd. I had an issue with my magnecor ht leads R100
Firstly I had misfire when boost was higher than 1,3 bar at 5000rpm and upwards.
Later the same issue appeared when I simply raise boost higher than 0,2bar.
Finally I had misfire all the time except idle.
I believe that there must be something like a magnet field from magnecors and engine loom but I m not sure yet.
Has anybody ever had the same issue? Any solution?

 

Are you sure its the HT leads? Easy way to prove it is to stick another make of leads on to see if the misfire stops.

 

I would also check the coil too ás i had that and the misfire disappeared when i changed to a group a coil

 

Would go back to genuine leads etc.
Read about misfire problems with some of the magnecor ones.

 

I 've installed BERU Silicone and misfires stopped!!!!
I saw something else, I have installed an APEXi AVC-R, I ve allways had a problem with rpm readings when I've raised rpms higher than 5000 rpms, APEXi reading raised up to 9000 rpm when my real rev limiter is 7200rpm.
When I've changed my leads to BERU my APEXi AVC-R reading are ok, now I see 7210-7230

 

Easy fix in the end then. What exactly is an APEXI AVC-R? Slightly confused about the rpm problem. Did you have higher readings than the real readings on your revcounter?