Dual Platinum Spark Plugs

[Slardy]

I was very disappointed when I learned that the FJR ignition uses a wasted-spark, 2 coil system. For those of your who don't know what this means, 2 of the FJR plugs are firing backwards, i.e. the spark jumps from the ground to the center electrode. Some, like me, were paying a premium for 4 Iridium plugs when 2 of them are firing from the base metal of the plug (probably some kind of S/S) TO the center electrode. The OEM NGK is just a good in this ground-spark situation.

So I did a little searching for plugs with premium metal on both electrodes and I found a dual Platinum plug (2 ground electrodes and one center electrode-all Platinum). And to boot, the dual ground electrodes have sharp edges facing the center electrode). I installed the plugs about 10,000 mi ago and checked them a few weeks ago in preparation for a long trip. The plugs were in beautiful condition, no crud, no visible metal removal, just a light cocoa color on all 3 electrodes and the insulator.

So now I am potentially benefiting the spark performance of all 4 cylinders.

Did I notice any improvement? No.

Am I suggesting that you use anything but the standard NGK which is very cheap? No.

But I thought you might be interested in my little experiment.

Slardy

 

[Ignacio]

Should I then ask for a refund since I've wasted about 1.06 billion sparks in the last 164,000 miles on the one set of Iridiums I put in when I first got the bike?

If had an extra billion sparks to spare I'd be able to run them until at least 300,000!

Inquiring minds want to know.

 

[pista]

Slardy, that's a different explaination then what I'm familiar with.

Actually I believe an engine that uses a "wasted spark" simply fires the plugs on both the compression stroke and exhaust stroke.

The spark on the exhaust cycle does nothing and is therefore "a wasted spark".

 

[radiummadman]

I think pista has it correct

 

[HotRodZilla]

Pista is correct. Two of the plugs spark when there is nothing to ignite. Basically, when the plugs are changed, these two plugs have fired twice as many times as the other two.

FWIW, I don't thing a plug can be forced to fire from the base. Regardless of the type of ignition system used to generate spark, the power still travels from the coil to tgw boot, to the top of the plug and then to the electrode.

 

[Allen_C]

Wait, so is there an advantage to using Iridium plugs or not!?

 

[SoCalFJR1300]

They last longer.

 

[Fred W]

No, Slardy does have it right.

In addition to the fact that the spark is "wasted" by firing both TDC cylinders simultaneously, the one at the top of the compression stroke (good) as well as the one at the top of the exhaust stroke (wasted), the fact that a single coil is firing those 2 spark plugs means that one is absolutely firing electrons from the center iridium electrode to the side (good) and the other is firing from (plain ole') side electrode to center (not so good).

I've pointed this dichotomy out many times previously, but people merely point their fingers and laugh as they continue to waste their money on iridium spark plugs that aren't doing anything for 50% of the cylinders.

But the good news is that other than the waste of their money it isn't really hurting anything, and it makes them feel better.

 

[Pterodactyl]

Huh?

 

[Allen_C]

Huh?

I think Fred is saying that the plugs work as the O.P. indicated. Iridium does nothing for you except possibly let you feel ok with waiting longer between plug changes.

 

[Denver_FJR]

Wait, so is there an advantage to using Iridium plugs or not!?

Well, there is for NGK.

 

[RaYzerman19]

To further educate you, the NGK Laser Platinum and the Laser Iridiums will indeed last longer than regular NGK's. The ground electrodes on those plugs have an iridium disc welded to them, made specifically for wasted spark systems where the coils have one positive and one negative polarity.

 

[Allen_C]

To further educate you, the NGK Laser Platinum and the Laser Iridiums will indeed last longer than regular NGK's. The ground electrodes on those plugs have an iridium disc welded to them, made specifically for wasted spark systems where the coils have one positive and one negative polarity.

These two?

https://www.ngk.com/product.aspx?zpid=30541

https://www.ngk.com/product.aspx?zpid=9679

 

[900gc]

The real question then becomes one of longevity and cost. Would you get 164,000 miles out of standard plugs?

I changed my '07 Honda pilot Iridiums out @100k following the manual service interval. They still looked close to new and the car still ran fine. The new ones did not change how well the car ran nor was there any change in fuel economy.

On the other hand: My '98 BMW E38 (740il) had Bosch Platinums (essentially standard plugs) I had run for about 70k. The car started running poorly so I took it to a highly respected independent German car shop, they hooked it up to their super computer and pulled the plugs after getting codes about sparking issues. The plugs were very much toast, so physically degraded that I was shocked the car ran at all.

2 different cars cars I know but in one the Bosch plugs were destroyed while the Iridiums were fine in the other. The main advantage I see to running Iridiums is to benefit from extended plug change intervals without degraded plug performance.

 

[Fred W]

These two?
https://www.ngk.com/product.aspx?zpid=30541

https://www.ngk.com/product.aspx?zpid=9679

No, neither of those plugs has an iridium or platinum side electrode. The second one has two side electrodes, so theoretically it might last twice as long. But even then you will not get all of the advantages that an iridium plug is supposed to provide.

As for iridium plugs lasting a very long time in modern auto engines, that is certainly true. But those engines are not wasted spark design, so all of the plugs fire from the center to the side. And the ignition systems were designed to make optimal use of those plugs. The FJR ignition system is fairly crude and was not designed for iridium plugs. Of course that doesn't stop folks from buying them, or from NGK in selling them to you at double the price.

What "wears out" a spark plug is the erosion of the negatively charged electrode. When the coil puts a high voltage potential across the spark plug's gap, excess electrons are built up on the negative side as compared to a lack of electrons on the positive side. When the difference in potential is high enough, an electrical arc (spark) occurs, which is the passing of a large number of those built up electrons through the air space between the two conductors.

Microscopic particles are ripped from the negative electrode along with the departing electrons, which causes the electrode's erosion over time. The advantage of iridium (or platinum) is that the metal is much harder and so does not erode as quickly. This allows the electrode to be made smaller. You'll notice that when comparing an iridium (or platinum) plug to a "standard" copper plug. The smaller diameter electrode concentrates the negative electrical charge, so that a lower voltage would be required to jump a given spark gap, or the gap can be made larger for better ignition.

But this concentration would only work in the "normal" direction, when firing from the center electrode. You can't concentrate a lack of electrons.

When firing from the side electrode, it is still the same size as normal plugs, so no concentration of charge would occur and the plug would fire at the same voltage as a "normal" plug. IOW the plugs firing in reverse might as well be normal plugs for all intents.

 

[RaYzerman19]

These are the ones I referred to:

https://www.ngksparkplugs.com/products/spark_plugs/laser_platinum.asp?mode=nml

https://www.ngksparkplugs.com/products/spark_plugs/laser_iridium.asp?mode=nml

With platinums or iridiums you might want to drop down one heat range, depending on evaluation of your current iridiums appearance, so Laser Platinum CR9EKPA or Laser Iridium CR9E1A-9

I'm not advocating the use of any particular plug, that's up to you and your wallet. I do however caution with any plug is that you do not install 'em and forget 'em. Once in a blue moon (no more than once a year), remove them, check condition and the real reason for this is so you know the threads are not seized into the head (although the metal coatings are designed to prevent this).

 

[3dogs]

.

Here is a graphic that show how a waste spark system operates. Also, GM, Ford and Chrys all made several millions of cars that used wast spark ignition systems. They call it DIS (distrbutorless ignition system). The red arrows show the path that the spark takes through the two spark plugs.

 

[Fred W]

And it is almost right. Electrons flow from negative to positive. (Hole flow theory is pretty outdated)

Other than the polarities shown at the coil secondary being reversed, this diagram is otherwise correct.

As for the big three automakers having used wasted spark in the past, that is (sadly) true. My 5.0L V8 Exploder had a wasted spark design. It called for double platinum plugs (both electrodes were platinum) and still the plugs never lasted 100k miles.

Nowadays, Coil Over Plug (COP) is all the rage, and this is what we now have in the 2013+ FJRs. Every plug fires in the normal direction, so iridiums would be beneficial on a 3rd gen FJR.

 

[RichDoyle]

Nowadays, Coil Over Plug (COP) is all the rage, and this is what we now have in the 2013+ FJRs. Every plug fires in the normal direction, so iridiums would be beneficial on a 3rd gen FJR.

I noticed that, perusing the wiring diagram. Another plus is no high-voltage spark plug wires whose insulation degrades with time. I had a SL350 that would "stimulate" the inside of my knees when ridden in the rain. And a Volvo that ran crappy in wet weather until I replaced the ignition wires.

The state of these plug wires is easily tested by grasping anywhere on the wire with one hand and the chassis of the vehicle with the other while the engine is running