Iridium plugs?

[ultimatt]

Who has used them? I know the factory spec calls for a twin plug, but my understanding is that type of plug was spec'd because it was the longest lasting plug at the time. Since the 3rd gen V6 models used a waste spark system plugs would wear at a 2x rate.

Fast forward to today and the Iridium plugs last 4x as long as a regular twin plug.

Can someone cite an actual technical reason we can't or should not use the long wearing Iridium plugs?

Thanks.

 

[triangles]

I have used double platinum for years. I'm not terribly familiar with how the ignition works on the T4R but on my previous vehicle with wasted spark ignition the spark would reverse directions every other cycle. In other words it would jump from the center electrode to the "finger," next spark would go from the "finger" to the center electrode, etc etc. This is why I used double platinum since it has a bit of platinum on both the finger and center electrode to reduce wear. Iridium plugs supposedly last even longer than the platinum ones.

Do the iridium plugs also have iridium on the "finger" similar to the double platinums?

I am curious if our T4R ignitions work in this fashion. Hopefully someone more knowledgeable can chime in.

 

[JayRolla]

Who has used them? I know the factory spec calls for a twin plug, but my understanding is that type of plug was spec'd because it was the longest lasting plug at the time. Since the 3rd gen V6 models used a waste spark system plugs would wear at a 2x rate.

Fast forward to today and the Iridium plugs last 4x as long as a regular twin plug.

Can someone cite an actual technical reason we can't or should not use the long wearing Iridium plugs?

Thanks.

Those iridium plugs will still wear down at a 2x rate. So they no longer last 4x. I ran my denso twin electrodes for over 100k miles before developing any type of misfire. They last a good amount of time.

Ive seen single electrode plugs look damn near melted off when taken out of this motor.

 

[Rock_Rat]

Who has used them? I know the factory spec calls for a twin plug, but my understanding is that type of plug was spec'd because it was the longest lasting plug at the time. Since the 3rd gen V6 models used a waste spark system plugs would wear at a 2x rate.

Fast forward to today and the Iridium plugs last 4x as long as a regular twin plug.

Can someone cite an actual technical reason we can't or should not use the long wearing Iridium plugs?

Thanks.

Toyota recommends NGK or Denso dual ground (for NA engines). That's good enough for me.

Tons of threads on here on this topic.

 

[19963.4lsr5]

The 96 had the iridiums in it when I bought it. Put 40,000 miles on it or so then it got recked and I put them in the 97 that replaced it. Then I put the EK OEM spec plugs in the 97. Noticed no difference. No change in mpg.


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[jgue467]

>>> previous vehicle with wasted spark ignition the spark would reverse directions every other cycle. In other words it would jump from the center electrode to the "finger," next spark would go from the "finger" to the center electrode, etc etc...

https://en.wikipedia.org/wiki/Wasted_spark

After reading this I can only see what is being described by triangles above as the last option, 'twin plug combusion' which i do not think applies to our beloved 5vz. :cowboy:

 

[triangles]

Nope that's not what I'm describing. What I was talking about was how the ignition coils charge and discharge and whether the current is flowing to or from the center electrode. Since it's been years if not decades since I learned how "modern" ignition systems work, I don't remember which direction current flow causes wear on which electrode so I'll speak in more general terms. When the current flows one way you only needed platinum plugs (platinum only in the center electrode) since the wear would occur only on the center electrode. These were called "single platinum" after the double platinum plugs came out. I don't know if it's with all but with some wasted spark ignition systems the current alternates direction so you would have wear at both the center electrode and "finger" (For clarity I'm intentionally not calling it the "ground" because technically speaking that isn't always what it is). This is why double platinum plugs were made with a bit of platinum on both the center electrode and the "finger" electrode. I suspect but am too lazy to confirm this is how the ignition system works on our T4Rs. If it doesn't then there's no reason to pay extra for double platinum over single platinum plugs.

Getting back to the OP's question. Since the only difference between platinum and iridium plugs is that the iridium plugs supposedly last longer I see no technical reason why you can't or shouldn't use iridium plugs. However IMHO with the platinum plugs lasting 100k miles Why would you want to spend extra money on Iridium? I guess if you're driving 100k miles/ year I could see that but it will take me almost a decade to get to put 100k miles on my T4R.

The dealer put OE plugs in my engine a couple years ago when I learned the expensive lesson that the PCM doesn't like non-oem (denso) O2 sensors. I figure rust will kill my T4R before these OE wear out so I just won't worry about replacing them with something longer lasting.

 

[SpidermanGeek]

when I learned the expensive lesson that the PCM doesn't like non-oem (denso) O2 sensors.

Wait, wut? I have 2 brand new Denso O2 sensors waiting to be installed. This is the first I hear of them potentially grenading a PCM.

 

[19963.4lsr5]

I have used double platinum for years. I'm not terribly familiar with how the ignition works on the T4R but on my previous vehicle with wasted spark ignition the spark would reverse directions every other cycle. In other words it would jump from the center electrode to the "finger," next spark would go from the "finger" to the center electrode, etc etc. This is why I used double platinum since it has a bit of platinum on both the finger and center electrode to reduce wear. Iridium plugs supposedly last even longer than the platinum ones.



Do the iridium plugs also have iridium on the "finger" similar to the double platinums?



I am curious if our T4R ignitions work in this fashion. Hopefully someone more knowledgeable can chime in.

That would be a lot of electronics to change the spark polarity if each coil many times per second to ensure the plug on combustion is forward firing.


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[TheDurk]

On our trucks it is a series circuit from one side to the other, so the current on the left side goes one direction and the current on the right side goes the other way. So you either need plating on both electrodes or change the plugs side-to-side halfway through the change interval.

I'm happy changing copper every 30k and have done so since 1999.

 

[nobb]

The plugs are so easy to change on this engine that using the OEM specified coppers are a non issue. I'd be mostly worried about using plugs with different specs and that might put unnecessary stress on the coils as those are $$ to replace.

 

[triangles]

Yes what TheDurk said!

SpidermanGeek, I worded that poorly. I meant the PCM doesn't O2 sensors that aren't OEM. I put Denso in parenthesis because they are the OEM sensors. I had $60 generic O2 sensors that I had installed. Long story short that didn't fix the problem and ended up costing mr over $1500 at the dealer after replacing a laundry list of things ending with the new OEM O2 sensors installed to get it running properly again.