Miss-firing CV8

[Aitch 'H']

Car started miss firing again today, it's been doing it every six weeks or so since having the AAS headers fitted as they foul the ignition leads. So I've swapped a couple of leads over that looked a bit sad but it hasn't helped. I don't think it's dropped a valve as all the cylinders appear to be getting hot when I touched the exhausts, I'm thinking its a plug breaking down as I have no idea when they were last changed as I've only owned the car for six months, anyone got any other ideas what it could be? Out of interest I've got some heat shield 'socks' coming at the end of the month to stop it happening again (hopefully!)

[Mud_]

Hmm, IIRC only one of the primaries should be worrying with the AAS headers, but I have heat socks on mine.

Definitely change the plugs...and the leads too if original.

[SturdyHSV]

Yeah, it'll be the headers being so close to the plug boot, have had this happen twice now.

They generally offer a pair of MSD ones, these have a boot that can be bent and hold that shape, the original one lasted a good few years. When I replaced it, I also tried those socks and the next one lasted a few months...

The area is so tight that the sock sits on the header, so it ends up making the whole thing hotter and wore the boot out far quicker!

Keep an eye on them once you fit them, if you see any discolouration on the sock (likely to be where the header is touching) then it's not going well!

[Mud_]

I have one discoloured sock where it is, as you say, in direct contact with the primary - will have to inspect the lead for evidence of a problem, but I haven't had any misfiring problems or noticed anything visual on the lead.