Could Magnecor leads be causing my misfire?

[PetrolEd]

Hello all,

Oh wow, finally my first post!

Well I've just given my Cerbera a good clean and checking over in anticipation for this fantastic summer we're going to get(!), and took the opportunity to fit a brand new set of the blue Magnecor ignition leads. Now when I was fitting them they didn't seem to give a particularly reassuring fit on the spark plug end, but were on as far as I could get them, and when pulled, felt as though they had been located correctly, albeit not very tightly. They didn't really 'click' on or off the spark plug. Anyway, it starts and runs fine, but whenever I give it some welly, it appears to misfire until the initial strain of the acceleration is out of the way. Sitting stationary and lifting the revs quickly, it constantly builds to about 4000rpm, before misfiring and refusing to go any higher. If you build the revs gently, it gives no trouble at all.

Now my questions are, as this may be an unrelated issue which simply developed since I last used it, but does it sound like the symptoms of ill-fitting leads, and also have any of you fitted Magnecor leads and had a similar experience with the fit? The plugs are the standard NGK's, so nothing unusual.

Cheers,
Ed

[big_treacle]

When I fitted my most recent set of leads I had to really push hard to get them to fit properly on the coilpacks. I had a bit of a missfire on high load so had another look at my leads. I went round every connection and found that with another hard shove, a couple of them clicked on properly & then everything was fine. They didn't look or feel loose before, but I guess they weren't quite on.
Also, I've found that it's easy to not quite get the leads on the plugs nearest the windscreen properly as they are a pain to get to. Probably worth double checking them.

[Gazzab]

Hello and congratulations on your first post.
I am sure there have been threads previously suggesting that 'upgrade' leads are not the way to go and that the standard ones should be used.
Anyway - the problem could be the leads and/or how ther are fitted but it could also be the coil packs. They often need replacing due to the heat build up.

[Gazzab]

ps love the beetle!

[PetrolEd]

Brilliant, thanks guys. I'd noticed the other posts about aftermarket leads, so I'm inclined to have another look at them this weekend, and if I can't improve them, go back to a set of standard leads to see if that makes any difference.

I'll look into the coil packs, you could well be right, I did have not too dissimilar symptoms on a previous Golf VR6 which I found to be exactly that issue.

Cheers,
Ed

[PetrolEd]

Gazzab said:

ps love the beetle!

Haha! My two cars are an unlikely pair aren't they! Ones fast, one's slow, but they're both extremely dangerous on the open road!

[jonbarrett]

I've fitted Magnecore leads. The secret for me was to grease the inside of each cap before putting it on. That way you can actually feel the connector snap onto the plug. Without greasing the caps it is impossible to know whethey they are on properly.

[PetrolEd]

Thanks Jon, I'll give that a try as well and see if that makes any difference. I take it that you've been running them since with no issues?

[gruffalo]

You mention in your original post that you had just cleaned her, did you change the leads and start her immediately after, if so it could be the coil pack have water on and/or in them, mine misfires when washed due to water running onto the coil packs but is fine in the rain.

(that's why I find it better to just drive her)

Having said that I have heard that the OEM plug leads are the best by far and that many have had issues with the Magnecor variant.

[jonbarrett]

My car had a missfire under load. Changed coils, leads and plugs and all was well. That was three years ago.

[JensenA]

I had Magnecor's on my Car. Took it for a service at Torque RVT, and while I watched, Ian ripped them out without even asking me with the words "I say Old Boy, these bighters need removing, I do believe they cause arcing old Chap". It ran a alot better with the TVR leads.

[PetrolEd]

Guys you've been really helpful, thank you! I'm absolutely sure they're the cause now. It did have a slight stumbling at low revs before I took it off the road over winter, and that's why I thought it could be linked to that same problem. However it sounds like the Magnecors have just added a whole new one! I'll get some OEM's ordered shortly, and lets see the difference they make.

Cheers,
Ed