Can a bad engine ground cause arcing. Ive noticed arcing around the coil, coil wire, and around the plug boots where they snap on the plugs.

I already replaced coil, cap and rotor, plugs, and wires.

 

Ever figure out what was wrong?Mine is arcing from the coil tower.My msd coil just died at a red light.I put the stock pne on and it was arcing.Thought it got messed up in storage so I bought a new oem replacement and the same thing is happening.Even tried a new wire.Same thing.

 

Yea i figured it out thx.

 

Well,what was it.Mines arcing out of the coil.Cant figure it out

 

When it's arcing out of a new coil with a new wire it must be caused by high humidity. Get some dielectric grease/paste and apply it to all insulator surfaces around the center contact. That is; pull the wire, apply grease to the whole coil top using a q-tip to get it on the inside of the tower as well, pull the boot from the wire and apply inside & out there too, and also onto the 1st inch of the wire.
With real high voltages, silicone wires, and high humidity you can get a blue corona and accompanying sounds even if the insulation is ok, but with paste on it won't grow into anything worse.
Bad engine grounds can't cause arcing at the coil tower btw.

 

We were dealing with the remnents of fay and it was raining when I was working on it.When I got it home itwas still wet undr the hood.I`ll try it.

 

Put another cap and new roter button and new plugs.Did the dielectric grease thing and no change.Any other suggestions.Gonna do new wires next.

 

Decided to check my msd box by disconecting it and running it stock and runs perfect.So I`ve got to find out if it was some bad wireing or if the digital 6 itself is bad.It was operating for sure but something aint right with it or the wireing.

 

So the MSD works all too well..
I can't imagine any wiring faults that could cause this apart from broken plug wires.
Check them for continuity. If the resistance is too high then a high energy system could drive the voltage up high.
Is it kind of a blue fizzle or a real hot spark? Is it a completely regular sparking?

 

Well,It ran fine for about ten minutes then started missing bad.I`ll get new plug wires this weekend.Cant spend anymore money on this thing till then or we`ll be hungry.So it may not be the msd box.It`s not arcing anymore but it`s missing bad.shakeing the whole car.Even has a little trouble staying cranked a couple of times.When it was arcing at first it was a clearly visible in daylight,blue spark/arc with a miss when it arced.I put a new plug wire on thecoil to cap and got it to not jump but you could hear it popping and when I put my finger about an inch or so away it would arc to my finger.Starting to sound like a bad wire.Cause when I touched the number 2 wire it would gimmie a little shock.I took it apart on the end and it had a bunch of black carbon build up in it.Cleaned it when I disconected the msd box.I`ve had carbon build up on several differant parts in the ignition system and it doesnt have but a few thousand miles on it.Why is that?Could my distributer be bad?BTW,Yes it was completly regularly sparking.

 

I traced it down to one bad plug wire that runs really close to the headers.There was no visible damage to the wire but it had a lot of carbon build up in the boot that goes on the plug.This seems kinda crazy that one bad plug wire fried my coil.I replaced and it runs perfect.Can the header heat cause that?

 

I was thinking about your problem and here is my guess as to what may have happened.

Originally the coil was designed to jump a spark across a 'specified GAP' of a spark plug. That gap probably looks like a 'resistor' of a certain 'resistance value' to the coil. So we can say the coil was originally designed to operate across a 'resistor' of a given 'value'. A given value of resistance would set the current handled by the coil to a specific 'current value'. Apparently the wire saw an 'easier path to GROUND', that being the metal of the header. So it jumped that gap instead. This new path to ground must have looked like a 'smaller value resistor'. With a smaller value of 'resistance', the coil was now part of a circuit that had to handle 'higher current' than what the coil was designed to handle. That higher current probably overheated the wire and the heat caused the insulation that covers the wire (inside the coil) to melt and that probably would cause the coil wire to SHORT or the coil wire to OPEN. If it 'shorted' then voltage to all plugs from that point on would be lowered, thus creating a smaller spark, if any. If the coil wire 'opened' then no spark to any plug would be available.

Guess the lesson is to check for any signs of spark jumping to places other than the spark plugs before it affects the integrity of components involved.

 

What happened here is more in the line of the plug wire being weakened at the point of the crimp in the boot. A small arc jumped across a small gap creating erosion and heat leading to a larger gap and hence a larger voltage drop.
When a coil fires it initially has a potential of 20-40 kiloVolts until the air in the spark gap breaks down. Then the voltage immediately drops down to 1-2 kiloVolts (plasma conducts current quite well).
A coil has a packet of energy (for each spark) that it wants to dump, and the voltage rises until it's able to pass a current through somewhere. Thus you can normally hold on to a plug wire (with its 2kV) but if you pull the boot (or there's an open circuit there) you immediately get zapped (with 40kV) because the voltage rises when there's no load.
The coil is designed to run with a load, and with constant 40kV pulses (even if just 1 out of every 8) the insulation eventually breaks down and it gets shorts in its windings. This corrupts the function, diverting the energy. If it were to stand continous open circuit it would have to be much larger to make room for the extra insulation needed.