Worn distributor bushings, or gear, could cause the arc if one of the other items mentioned were already marginal.

 

I popped the top of the distributor, it's pretty worn, as are the rotor in it. The gear seems tight though, just cap+rotor worn, but I do get spark (an arc) on the coil.

I'll get a used one and try it, same as a 3rd coil, that way I'll be working with something 100% different. But I almost sense it's the distributor...what are the odds that a different coil + wire would cause arcing also?

 

Electricity takes the path with the least resistance to ground. It's jumping a 1/2" gap at the coil in your video, which means there is less resistance to ground there, than where it's supposed to be going to ground, (ultimately this is at the spark plug ground electrode). This means there is high resistance somewhere in the secondary ignition system. That could be, as I mentioned earlier, the ignition coil, coil wire, spark plug wire, spark plug, distributor cap & rotor. It could also be a combination of any or all of those components.

 

Where would I find this Spark Plug Ground Electrode to check it?

 

So I'm stuck until tomorrow until I can get a new distributor, so I'll ask some questions.

1 - Would the arcing cause the MAP sensor PO108 code to come on? (I believe it would due to the stray voltage finding its way into the lines)..and would it destroy my MAP sensor or just cause it to read wrong? (I haven't had the po108 code back at all)

2 - If the distributor isn't working proper it can cause the arcing around the ignition coil as seen in the video (I tried 2 separate coils, 2 separate wires, both arced)

3 - Is the distributor grounded anywhere I can check? I've searched but can't find anything besides the wires going into it...all grounds seem good unless I'm missing one or 2 (which could be possible...and where is the spark plug that would affect the coil?)

4 - If the ignition coil isn't getting it's proper voltage due to it arcing out, this would cause a no start condition correct?

 

The spark plug ground electrode is at the base of the spark plug:



Spark from the ignition coil must make it to this point before arcing to ground.


1. Arc will not cause the MAP sensor DTC or harm the sensor.

2. If distributor bushings are worn excessively it can cause erratic spark distribution due to a wobble in the distributor shaft.

3. The distributor housing is plastic and does not require a ground. Some replacement distributor housings are cast, and they do not require a ground. The distributor cap, rotor and camshaft position sensors are the important components that are housed by the distributor and none of them should be grounded.

4. The ignition coil most likely is getting proper voltage. The coil is a step up transformer and increases voltage from battery voltage to somewhere in the neighborhood of 40,000 volts. Battery voltage might jump 1/16" but 40,000 volts can jump up to 3/4", possibly more depending on atmospheric conditions. Whenever there is high resistance in the coil wire, air gap between the rotor and the cap, terminals or routing of the voltage inside the cap itself, any of the plug wires or spark plugs, the spark can arc to ground. In your case, the path of least resistance is to the coil bracket. Each time a spark arcs to ground, it means a spark plug is not firing. With one or two arcing the engine will run rough, get enough of them arcing and the engine will not start or run. I would suggest replacing the distributor cap, rotor and plugs with AC Delco parts, and also a good quality set of spark plug wires, ie AC Delco, Autolite, or Belden. Put a dab of silicone dielectric grease on each terminal of the cap, (inside and out) and also at the spark plug end of each wire.

 

Sorry. A bad distributor will not cause that.
A bad cap and rotor MIGHT. Or if the dist is totally off registration so the rotor is between posts on the cap. If the truck ever ran at all since you moved the distributor, that aint it.
- and nothing on the distributor needs grounded even the pickup.

And that coil is good. That is a strong spark. Only issue MIGHT be if the coil tower is cracked.

Nope that is MOST likely a wires problem and at least one has to be OPEN for that to happen. Arcing to metal or another wire wont do that.

Cheap wires are made with graphite impregnated fibreglas centers. Once there's a weak point it will burn away the graphite.

 

The truck hasn't ran since I parked it Thursday. It seemed to have run just fine until them. I replaced the MAP and Ignition Coil to no effect, still arcing like mad.

I tried a new rotor and it still arced (haven't been able to get ahold of a cap...damn small towns).

So when you say wire, you mean sparkplug wire or another wire altogether?

 

The MAP sensor has absolutely nothing to do with spark. What you are seeing when the spark jumps from the ignition coil to ground is a result of a secondary ignition part, or parts, failure, obviously NOT the ignition coil itself.

I would suggest replacing the distributor cap, distributor rotor and spark plugs with AC Delco parts. Also replace the spark plug wires with a good quality set such as AC Delco, Autolite, or Belden. Put a dab of silicone dielectric grease on each terminal of the cap, (inside and out) and also at the spark plug end of each wire.

 

I thought about it for a while...how can I test if one of the sparkplugs or the associated wire is causing the arcing? Then I came to the easiest time saving idea ever.

I removed each plug from the distributor cap, had my wife turn the engine over. No matter what plug was removed I had arcing. Only thing I haven't tried is removing all the plugs at once (which IMO would cause no arc, but I just thought of doing that now so it'll have to wait lol).

I don't know if that is a good way to test for sure, especially if more than 1 plug is bad (which I doubt), but it gives me a good idea that I'm looking at a bad cap/rotor/distributor.

Let me know if that was a good idea...with 31" tires there's really not alot of room to get into the wheel well to remove the plugs/wires from that side. Add that to the rain I'll be seeing tomorrow ( Sad Tuba ) and it won't be fun lol.

Junkyard here I come lol.