Coil on Plug Passat Video

Hi Paul and all, here in England I’ve been following your diagnostic techniques and video footage from problem jobs you have came across, what a pleasure to see and enjoy. Myself Master technician for Volkswagen have used a few of your diagnostic techniques and to be honest are better than the Vw factory methods. One of your videos I have watched was at the college you help train at, Vw passat non start the ignition system you spoke about is exactly a 4 pin coil wasted spark set up, what I can’t get my head around is when you mentioned that the spark comes from the engine block and back into ignition coil? Can you explain this as surly when the magnetic field collapses a spark is induced flowing down the spark plug to the engine block? 

Does the flow of current flow in the opposite direction? Instead of flowing down the centre electrode then to the bent part on the spark plug?

Any ideas guys? Paul can you explain?

ajwebby wrote:

...wasted spark set up, what I can’t get my head around is when you mentioned that the spark comes from the engine block and back into ignition coil? Can you explain this as surly when the magnetic field collapses a spark is induced flowing down the spark plug to the engine block? 




 

On a waste-spark system, there are two cylinders/spark-plugs fired at the same time. As the magnetic field in the coil collapses, the Secondary current flows from the coil to the first spark plug, to the engine block, through the engine block to the second spark plug and, then, back to the coil.

Does the flow of current flow in the opposite direction? Instead of flowing down the centre electrode then to the bent part on the spark plug?

Yes, well, kind of....  The current makes a big loop. If you look at the secondary waveform of the first spark plug and the secondary waveform of the second spark plug, you will see that one waveform will be upside-down, and the other will be right-side-up.  The first spark plug's secondary waveform will be upside-down as current flows from the coil, to the spark plug. The second spark plug's secondary waveform will be right-side-up, as current flows from the spark plug back to the coil.

So are we saying that the grounded wire current will flow down here across the engine block then sparks from the engine block to the centre electrode back into the secondary winding?

From Paul’s video of the passat 4 pin coil the spark came from the engine block as one side of the secondary winding is grounded?

ajwebby wrote:

So are we saying that the grounded wire current will flow down here across the engine block then sparks from the engine block to the centre electrode back into the secondary winding?
 

Yes.  Similar to the 12v dc battery/load current path, electrons will flow from Positive-to-Negative ( <---this is open to discussion/debate, too ), taking the path of least resistance. Except in this case the source and termination of current is the coil, not the battery. Current leaves the coil, and takes the path of least resistance BACK to the coil, jumping the gap of both spark plugs, along the way.

Keep in mind that I am not an electrical engineer. I have a, very, basic/working understanding, at best.

ajwebby wrote:

From Paul’s video of the passat 4 pin coil the spark came from the engine block as one side of the secondary winding is grounded?
 

Can you post a link to the video that your are referring to?

Here is a SD Premium video that has a good visual explanation of a waste spark system.

4 pin coil the 4th wire is grounded…near the end of the video Paul teaches this

Ok. That clears things up, a bit. This is not a waste spark system. You are referring to the 4th wire of the a 4-wire COP. Engineers take liberties in how they achieve their end results. I cannot explain why they have taken this route.

Paul compared this design to a waste-spark system with one shorted plug wire.

As for the spark coming from the block, to the spark plug, that is what I was referring to in a previous post...

electrons will flow from Positive-to-Negative ( <---this is open to discussion/debate, too )

It is typically thought, taught, and explained that electrons flow from Positive-to-Negative. However, the opposite is true. I suspect that is what Paul was describing.
 
Here, is an animation if found with a quick google search.



 

How i am looking at the COP design, the 4th wire is grounded allowing current to flow down this wire across the engine block at up through to the centre electrode this is the loop, mutual induction is the flow of current but in the opposite direction therefore the spark comes from the engine block…I think this is why Paul mentioned this in the video?

Can Paul jump in here to confirm please?