Ignition Wire Problems Part 3

Yes I dont run the covers at all, I mean it don't rain here much

Those spacers would be great, put me down for a set if your making them
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It is unlikely to have so many wires go bad. I would start looking at your coils next.

 

Yes, it is possible. to measure the DC resistance, get a reading to be good, and it is bad in use. The DC resistance is only one spec to measure, and at a frequency that is ... not used in practice.

 

Sparking between the wires and the wires and valve covers (read ground) means one of two things, either the dialectric strength of the wires is inadequate for the voltages or the coils are overvolting. If the wires meet the OEM dialectric spec, check your coils. Can't imagine what else it could be.

 

I don't claim to be an expert on 355's, but I wonder if perhaps your engine isn't grounded properly to the frame. For experimentation, you might want to just run a jumper wire or cable from a bare metal spot on the engine to a good solid grounding spot on the frame, and see if that makes a difference. It would only take a couple of minutes....

 

+1 on the ground.

 

My initial thoughts as well

 

That one's simple enough that we should have an answer tonite.

 

The 355 M5.2 parts diagram on Ricambi's site (table 53, item 63) shows a fairly short, braided cable that APPEARS to be located in the vicinity of the alternator, and SHOULD securely ground the electrical system on the subframe. If this cable is present, and tightly connected on each end, then the engine should be satisfactorily grounded, and NOT the source of your problem. I see that you had alternator issues in the past, is it possible that this cable was left off, or loose? It would be interesting to know if your resistance reading changes as the engine warms up.

 

Poor ground doesn't make a lot of sense. The plugs are grounded to the block. The valve covers are grounded to the block. Same ground path.

 

This is all very odd. I may have missed it but are you sure none of your current wires are damaged/nicked anywhere? (from being previously squished?) I see what appears to be tape around one of the plug boots as well.

 

Any pics of your end terminations?

 

I can't tell from the pic but the conductor is folded over behind the crimped terminal?

Also, do you mark the wires for depth or can you hear them click onto the post inside of the boot?

Seems basic I know, just want to confirm.

 

I hate to bring this up again, but it's still sounding like corona discharge.

 

Maybe this is a longshot, but it seems you're at a point where even longshots are worth considering: could your wires be contaminated with something that's compromising their insulation properties? For example, if you've handled them with hands that were contaminated, you could have transferred carbon-, or even metallic-contamination to the jackets of the wires? I've done this inadvertently before, when my greasy/oily hands transferred 'fingerprints' containing conductive contaminants (even dust) to the surface of the insulator, making it somewhat conductive. If your wires have black or dark insulation, you might not be able to see the contamination, even if it's sufficient to support the arcing or corona discharge you're seeing.... anyway, maybe a longshot, but cleaning the wires well might make a difference...