The ignition coil cult

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mikenixon
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Re: The ignition coil cult

#31

Post by mikenixon »

gltriker wrote:With recently installed, properly gapped (0.028") NGK DR8EIX spark plugs into very clean cylinder head threads and no anti seize or other dressing applied, why would the lower spark plug wire outlet, on both green 3ohm Dyna ignition coils, provide so much more delivered potential than their respective upper spark plug wire outlet can provide?
I would think the spark plug on the untested output terminal has deposits that are conducting to ground, thus increasing the output on the tested terminal. Or visa-versa, the low observed output terminals are low because their untested terminal twins have excessive resistance in wires or plugs, resulting in less voltage at the tested terminal.

Here's a simpler way to look at it, and hopefully this will bring it home. I mentioned this in article probably two years ago. The dual output coil fires in a loop, a circle. The source is the center of the secondary winding, the loads are the two series-wired plugs, the return is to the center of the winding again. I have found that if you ground one of the terminals on a dual output coil, this concentrates all the electrical energy on the remaining terminal, increasing its voltage. I mentioned this before. One way to get instant high voltage ignition coils is to ground one of the twins. Of course now you need four coils instead of just two, and there are problems on the primary side, but electrically it works. I've done it. This weirdness explains what I said above about one output from a dual output coil having higher voltage if its twin has a spark plug that is bleeding voltage to ground. The very simplest explanation and one that fits the above is the untested plugs were not grounded to the same integrity as the tested ones.

It's reaching, but I can't see any other explanation, and this theory at least I have proven in operation.

So, no one is going to ask about the BMW special design?
Last edited by mikenixon on Sat Aug 08, 2020 4:54 pm, edited 1 time in total.
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Re: The ignition coil cult

#32

Post by mikenixon »

pidjones wrote:I would theorize that since the coils put out DC, one end + and one -, that the lowers provide which ever polarity is more prone to jumping from a larger diameter electrode. Put a point-to-point tester on both, and I would suspect that they both produce the same. Even the plugs don't provide the most ideal geometry for both to fire equally, but at the short distance it doesn't matter much when igniting fuel. As Mike has noted in a previous discussion, careful observation of used plugs will reveal one of each pair with center electrode eroded, while the other will have the ground electrode eroded.
It's a good thought, but in my experience and understanding of the theory, the difference would not be so much that it would be observable in the color and strength of the spark. This is in fact one reason why the spark plugs whose special design is supposedly intended to mitigate the forward and reverse firing (U-Gap and Splitfire) don't actually offer any benefit. There is so little energy difference in forward versus reverse firing it just doesn't matter. I like the path you're on though...
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Re: The ignition coil cult

#33

Post by pidjones »

mikenixon wrote:
pidjones wrote:I would theorize that since the coils put out DC, one end + and one -, that the lowers provide which ever polarity is more prone to jumping from a larger diameter electrode. Put a point-to-point tester on both, and I would suspect that they both produce the same. Even the plugs don't provide the most ideal geometry for both to fire equally, but at the short distance it doesn't matter much when igniting fuel. As Mike has noted in a previous discussion, careful observation of used plugs will reveal one of each pair with center electrode eroded, while the other will have the ground electrode eroded.
It's a good thought, but in my experience and understanding of the theory, the difference would not be so much that it would be observable in the color and strength of the spark. This is in fact one reason why the spark plugs whose special design is supposedly intended to mitigate the forward and reverse firing (U-Gap and Splitfire) don't actually offer any benefit. There is so little energy difference in forward versus reverse firing it just doesn't matter. I like the path you're on though...
Well, electrons will stream much more easily from a sharp point or edge (edge of the cap's connector or end of the wire) than say, the nice rounded valve cover.
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Re: The ignition coil cult

#34

Post by Track T 2411 »

I was going to ask about the BMW design earlier, but had to digest the info already given...
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Re: The ignition coil cult

#35

Post by mikenixon »

pidjones wrote:
mikenixon wrote:
pidjones wrote:I would theorize that since the coils put out DC, one end + and one -, that the lowers provide which ever polarity is more prone to jumping from a larger diameter electrode. Put a point-to-point tester on both, and I would suspect that they both produce the same. Even the plugs don't provide the most ideal geometry for both to fire equally, but at the short distance it doesn't matter much when igniting fuel. As Mike has noted in a previous discussion, careful observation of used plugs will reveal one of each pair with center electrode eroded, while the other will have the ground electrode eroded.
It's a good thought, but in my experience and understanding of the theory, the difference would not be so much that it would be observable in the color and strength of the spark. This is in fact one reason why the spark plugs whose special design is supposedly intended to mitigate the forward and reverse firing (U-Gap and Splitfire) don't actually offer any benefit. There is so little energy difference in forward versus reverse firing it just doesn't matter. I like the path you're on though...
Well, electrons will stream much more easily from a sharp point or edge (edge of the cap's connector or end of the wire) than say, the nice rounded valve cover.
Yes in theory. But it makes no actual difference to a spark plug, which the whole U-Gap debacle proved.
Last edited by mikenixon on Sat Aug 08, 2020 8:04 pm, edited 1 time in total.
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Re: The ignition coil cult

#36

Post by mikenixon »

Track T 2411 wrote:I was going to ask about the BMW design earlier, but had to digest the info already given...
The old air-cooled BMW Boxer engine helps explain how a dual-output ignition coil can have a fault on one secondary leg and not the other. Wait for it...

An ignition coil has two windings, one wrapped around the other. In a collapsing field ignition system, the ignition coil's secondary winding is typically found at the center, and the primary on the outside. This is more efficient as when the primary's magnetic field collapses, the lines of magnetic flux as they fall inward naturally cross the secondary. In a dual-output (as opposed to single-output) coil the two windings have no electrical connection. However, if stressed highly enough, the secondary winding can arc through its internal insulation to the primary winding. Once it has done this a few times, the principle of "path of least resistance" comes into effect and the coil will stop working correctly, always instead simply arcing within itself. This is why an ignition system must be disabled if the plug wires are loosened from their plugs and not grounded and the engine turned over, because otherwise the ignition coils can be ruined, and also incidentally why Honda led the way long before the other three Japanese manufacturers in wiring their engine kill switches in such a way that the starter can still turn over but the ignition is deadened. They did this decades before the other makers, for this very reason (the other brands wired the kill switch into the starter, making damaging ignition coils much more likely during say, cylinder compression tests. For many years this was just one of many of the differences between Honda and the other three).

This tendancy to arc secondary to primary is so great that as I say, once it happens and burns off the lacquer insulation, it will keep doing so. If this happens in a dual-output ignition coil, the result will be that one plug will get the bulk of the energy, just as with my grounded-back secondary hyped-up coil example discussed earlier. This is one of the ways a dual-output coil will have a fault in one output but not the other, despite the two outputs being in series. So, it is not correct to say a dual-output ignition coil can't ever fault on only one side, it certainly can, and this is only one way that it can.

The fact that this actually happens is borne home by something BMW did. BMW trained its dealers to adjust the Boxer engine's carburetors by running one cylinder at a time, and this by unplugging one plug wire at a time, a very bad practice on the face of it, as explained above. Except that the Boxer equipped bikes' ignition coils were specially made to withstand this unwise technique by virtue of having a "grounding" terminal, a kind of "lightning rod", if you will, that the overstressed secondary could arc to and not arc over to the primary, thus preserving the ignition coil. Cool, huh?
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Re: The ignition coil cult

#37

Post by gltriker »

mikenixon wrote:
Track T 2411 wrote:I was going to ask about the BMW design earlier, but had to digest the info already given...
The old air-cooled BMW Boxer engine helps explain how a dual-output ignition coil can have a fault on one secondary leg and not the other. Wait for it...

An ignition coil has two windings, one wrapped around the other. In a collapsing field ignition system, the ignition coil's secondary winding is typically found at the center, and the primary on the outside. This is more efficient as when the primary's magnetic field collapses, the lines of magnetic flux as they fall inward naturally cross the secondary. In a dual-output (as opposed to single-output) coil the two windings have no electrical connection. However, if stressed highly enough, the secondary winding can arc through its internal insulation to the primary winding. Once it has done this a few times, the principle of "path of least resistance" comes into effect and the coil will stop working correctly, always instead simply arcing within itself. This is why an ignition system must be disabled if the plug wires are loosened from their plugs and not grounded and the engine turned over, because otherwise the ignition coils can be ruined, and also incidentally why Honda led the way long before the other three Japanese manufacturers in wiring their engine kill switches in such a way that the starter can still turn over but the ignition is deadened. They did this decades before the other makers, for this very reason (the other brands wired the kill switch into the starter, making damaging ignition coils much more likely during say, cylinder compression tests. For many years this was just one of many of the differences between Honda and the other three).

This tendancy to arc secondary to primary is so great that as I say, once it happens and burns off the lacquer insulation, it will keep doing so. If this happens in a dual-output ignition coil, the result will be that one plug will get the bulk of the energy, just as with my grounded-back secondary hyped-up coil example discussed earlier. This is one of the ways a dual-output coil will have a fault in one output but not the other, despite the two outputs being in series. So, it is not correct to say a dual-output ignition coil can't ever fault on only one side, it certainly can, and this is only one way that it can.

The fact that this actually happens is borne home by something BMW did. BMW trained its dealers to adjust the Boxer engine's carburetors by running one cylinder at a time, and this by unplugging one plug wire at a time, a very bad practice on the face of it, as explained above. Except that the Boxer equipped bikes' ignition coils were specially made to withstand this unwise technique by virtue of having a "grounding" terminal, a kind of "lightning rod", if you will, that the overstressed secondary could arc to and not arc over to the primary, thus preserving the ignition coil. Cool, huh?
Very coil. ooooops, I meant Cool! ;)
Thank you. tumb2
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Re: The ignition coil cult

#38

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:)
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Re: The ignition coil cult

#39

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mikenixon wrote:
Track T 2411 wrote:I was going to ask about the BMW design earlier, but had to digest the info already given...
The old air-cooled BMW Boxer engine helps explain how a dual-output ignition coil can have a fault on one secondary leg and not the other. Wait for it...

An ignition coil has two windings, one wrapped around the other. In a collapsing field ignition system, the ignition coil's secondary winding is typically found at the center, and the primary on the outside. This is more efficient as when the primary's magnetic field collapses, the lines of magnetic flux as they fall inward naturally cross the secondary. In a dual-output (as opposed to single-output) coil the two windings have no electrical connection. However, if stressed highly enough, the secondary winding can arc through its internal insulation to the primary winding. Once it has done this a few times, the principle of "path of least resistance" comes into effect and the coil will stop working correctly, always instead simply arcing within itself. This is why an ignition system must be disabled if the plug wires are loosened from their plugs and not grounded and the engine turned over, because otherwise the ignition coils can be ruined, and also incidentally why Honda led the way long before the other three Japanese manufacturers in wiring their engine kill switches in such a way that the starter can still turn over but the ignition is deadened. They did this decades before the other makers, for this very reason (the other brands wired the kill switch into the starter, making damaging ignition coils much more likely during say, cylinder compression tests. For many years this was just one of many of the differences between Honda and the other three).

This tendancy to arc secondary to primary is so great that as I say, once it happens and burns off the lacquer insulation, it will keep doing so. If this happens in a dual-output ignition coil, the result will be that one plug will get the bulk of the energy, just as with my grounded-back secondary hyped-up coil example discussed earlier. This is one of the ways a dual-output coil will have a fault in one output but not the other, despite the two outputs being in series. So, it is not correct to say a dual-output ignition coil can't ever fault on only one side, it certainly can, and this is only one way that it can.

The fact that this actually happens is borne home by something BMW did. BMW trained its dealers to adjust the Boxer engine's carburetors by running one cylinder at a time, and this by unplugging one plug wire at a time, a very bad practice on the face of it, as explained above. Except that the Boxer equipped bikes' ignition coils were specially made to withstand this unwise technique by virtue of having a "grounding" terminal, a kind of "lightning rod", if you will, that the overstressed secondary could arc to and not arc over to the primary, thus preserving the ignition coil. Cool, huh?
This is an excellent and informative thread. many thanks.
i am going to assume that the internal insulation is compromised in some way, and toss the coil.
may cut it open and have a squiz , see how they are made. i am not overly impressed with Dyna product. and
even less impressed with the tech answers. i have had 3 sets of modules fail and now this.
The bike in question now has a C5 fitted. i bought a couple of them and had one in a box on the shelf.
i note that the fellow who produced the C5 , no longer makes them . a pity, but i believe he is researching new
suppliers of components. the previous supplier was PowerArc and in six or seven years i have had no issues.
Again, many thanks for the comments and information .
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Re: The ignition coil cult

#40

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:)
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Re: The ignition coil cult

#41

Post by Sidecar Bob »

Just to set the record straight, I happen to have a set of original GL1100 coils in my shop right now so I went out there and checked: There is no continuity between the spark plug leads and ground.

As has been said many times before by myself and others, one end of the secondary is connected to each spark plug and the circuit is completed through the engine block, heads &c. On the face of it one would expect that if you disconnected one plug lead the other one on that coil would cease to fire. The arcing between secondary & primary explains how it is possible for the other plug to continue to fire and I would think that if that is happening it may be time to replace that coil.

BTW re BMW boxers: The Dnepr motorcycles imported into Canada in the '80s did not come with tachometers. The "Owner's Manual" (more like a FSM) that came with them said to put the bike in the centrestand, start the engine and put it in gear (can't remember if it was 1st or 2nd), turn the throttle until the speedometer showed 50 Km/h and use locking pliers (Vise-Grips) to hold it there while alternately removing the plug caps to make sure the speedo read the same when running on either cylinder. Not exactly the safest procedure but you only had do do it every 10,000 Km or so.....
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Re: The ignition coil cult

#42

Post by Sidecar Bob »

I meant to mention: Even though the stock coil's secondary winding has no connection to ground it would be theoretically possible to produce them with either 2 secondary windings (one for each plug, with the other ends of those windings grounded) or with a single winding with a centre tap connected to ground.
I don't know if any of the aftermarket manufacturers did that (or even if it would be practical to do so) but if they did disconnecting one plug would not prevent the other one from firing.
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