Ignition coils...

[JBDrifter]

I recently had a problem with my car running rough (missing) at certain revs and under load, in particular while running on gas, which was diagnosed as a failed coil. I was told there was no way to test which coil it was that was buggered, so trial and error was the only method of finding the faulty one. Well I got very lucky it seems and got it on the first attempt.

That was about 3 months ago. The problem has come back again and before I tackle it again I'd just like to know if there is in fact any way of testing exactly which coil it is to save me having to go through the trial and error process.

And I'm also wondering if anyone knows of any causes of this issue? Is there something else in the ignition system that might be causing the coils to fail, or something else that should be replaced to ensure them a longer life? I don't want to fix it only to have another one fail in a couple of months.

[BerlinaBen]

I haven't checked with the VZ's but you should be able to measure the resistance of each coil. This should tell you witch one is bung, although if it is an intermitant fault, it may measure okay anyways. I don't envy you. Would be a pain in the butt lifting the manifold off to replace each coil one by one.
Good luck.

[JBDrifter]

I haven't checked with the VZ's but you should be able to measure the resistance of each coil. This should tell you witch one is bung, although if it is an intermitant fault, it may measure okay anyways. I don't envy you. Would be a pain in the butt lifting the manifold off to replace each coil one by one.
Good luck.

There are a couple you can get out without having to lift the manifold, and luckily enough it was one of those two last time. I might just have to lift the manifold and test each coil for resistence and hopefully find the faulty one.. only having to lift the manifold once. Thanks for the tip.

[Nic Nac]

I found that by using a 240volt neon test screwdriver -the type you hold your thumb on the top of - and holding the blade end on top of the coil about midway on the right hand side of the shiny black top of the coil, the good ones will show a flash each time the coil fires. The faulty one will not. May need a bit of trial and error to find the right spot.