Faint ignition noise since COP kit fitted

[Heaveho]

Hi, as title, been there for years, and remained when I changed to a different head unit. It's definitely the coils causing it. I haven't been especially bothered by it, but I'm in the mood to fix things, and this is next. I've no idea where to start though. I'm guessing it's an earth problem, but it appeared immediately after changing to this setup.

[GreenV8S]

Have you tried adding ferrite beads to the power supply for the audio system? That will damp down noise on the supply lines. You might even need to add some filtering. Also confirm the ignition amp and ECU are grounded to the battery directly rather than via the shell.

[Heaveho]

Thanks, I'd never heard of ferrite beads. I'm interested in trying to find out why the COP kit has caused this to happen, I feel like if I can understand that or have i explained to me, I can better isolate the source. I'm guessing it's just not as well earthed or shielded as the original set up.

[GreenV8S]

Heaveho said:

I'm interested in trying to find out why the COP kit has caused this to happen,

It may be causing noise on the 12V supply.

[Heaveho]

GreenV8S said:

Heaveho said:

I'm interested in trying to find out why the COP kit has caused this to happen,

It may be causing noise on the 12V supply.

The earth(s) appears to be integrated into the supplied wiring of the COP kit, and disappears off into the original harness where it plugs in to the standard connectors. The original coils would, I imagine from their design, be earthed through their metal body, as they were attached directly to the head by bolts. The new kit has the 4 coils mounted on a carbon fibre valley plate, and the mounting bolts have no way of providing a direct earth from the body of each coil, as they're isolated from any form of directly reaching a ground.

Is there any way I can attach an external earth from each coil to see if it makes a difference? I understand there's a possibility I might introduce a ground loop here, but it's obviously easily reversed if I make it worse.

[GreenV8S]

I can't guess whether your new coils are designed to be earthed through their mounting bolts. You could always try running a direct wire from the bolts to battery ground to see whether that helps. If so, then you'd need to figure out how to implement that as a permanent solution.

[Heaveho]

GreenV8S said:

I can't guess whether your new coils are designed to be earthed through their mounting bolts. You could always try running a direct wire from the bolts to battery ground to see whether that helps. If so, then you'd need to figure out how to implement that as a permanent solution.

Cheers, that won't work unfortunately, as the coils are mounted by a bolt that passes through the plastic, with only a metal sleeve around it to prevent over tightening. I rang a motorsport company who supply COP kits today and aren't just a retailer, but seem to know their stuff. They seem to think if I can identify the powered ground wire, I can just relocate this to a bolted ground on the head, so that's the next plan. When someone in the industry says " That's what I'd do if it were mine ", I tend to think I've found the right place!

Thanks for the replies and suggestions, I'll try and remember to update if I solve it.