Iridium plugs at 300,434 miles

[Skid]

These are off the rear bank of my dad's 2005 Toyota Sienna. 3.3 liter V6 (3MZ-FE). What a PITA it was (you have to take off the cowl and the intake plenum to get to the plugs). Anyway, the car set a P0300 code (Cylinder 1 misfire) at 295,777 miles. I reset the code then, and it hadn't come back, but I changed the plugs anyway at 300,434. From left to right, the plugs are for cylinders 1, 3, and 5 respectively.

 

[dblshock]

impressive.

 

[slacktide_bitog]

I hope you also replaced the valve cover gasket while you were in there, and maybe the fuel injectors too?

You should not have used the iridium power plugs (they won't last as long as the OE ones), You should've replaced them with the same long life plugs, considering how difficult it is to change them

 

[Skid]

Originally Posted By: slacktide_bitog
I hope you also replaced the valve cover gasket while you were in there, and maybe the fuel injectors too?

You should not have used the iridium power plugs (they won't last as long as the OE ones), You should've replaced them with the same long life plugs, considering how difficult it is to change them

Didn't know there was a difference! Good to know.

 

[dblshock]

I thought the good denso's had a thinner electrode than either pictured.

 

[BrocLuno]

300K and you are worried about long life ... They'll last long enough

 

[Brybo86]

Any pics of the valvetrain? Underside of the valve cover?

 

[CR94]

What change interval did Toyota recommend?

 

[Tomioka]

The iridium powers don't have the platinum disc in the ground electrode so they are not a long life plug. I had NGK Iridium IX spark plugs and by 45,000mi the ground electrode started wearing while the tip still looked good.

Long life spark plugs also suffer from wear as they increase in resistance that's why most mfgrs recommend a 100,000mi spark plug change interval.

 

[demarpaint]

That's pretty impressive. You're lucky they came out w/o problems.

 

[ARB1977]

At what interval? 300K on original plugs and look that good. Kinda hard to beleave.

 

[Kira]

You say there's a plug called "NGK Iridium Power" and that is the long life plug.

Just need to know the name so I can buy them. 300,000 is super impressive.

 

[pbm]

I changed the OE Iridiums (Densos, I think) at approx. 100K in my 08' Corolla.....I used NGKs....I'm of the opinion that ANY Iridium plug should last 100K.

If I had an engine that was a real PITA to change the plugs, like this 3MZ-FE, I'd look for the longest lasting Iridium I could find.

 

[DrRoughneck]

Can iridium plugs be used in an engine calling for regular copper plugs?

 

[FastLane]

You can use iridium plugs in anything you want.

 

[slacktide_bitog]

Originally Posted By: Kira
You say there's a plug called "NGK Iridium Power" and that is the long life plug.

Just need to know the name so I can buy them. 300,000 is super impressive.


NGK's long-life plug is called Laser Iridium. Denso's is called Iridium Long Life

Originally Posted By: CR94
What change interval did Toyota recommend?


100k or 120k

Originally Posted By: pbm
If I had an engine that was a real PITA to change the plugs, like this 3MZ-FE, I'd look for the longest lasting Iridium I could find.

Originally Posted By: DrRoughneck
Can iridium plugs be used in an engine calling for regular copper plugs?


Yes, but it would be a waste of money. The only time I'd use iridium where the OE is copper is if the plugs are difficult to do on that particular car/engine

 

[DrRoughneck]

Originally Posted By: FastLane
You can use iridium plugs in anything you want.

Let me rephrase my question: will it work well?

 

[SirTanon]

Originally Posted By: DrRoughneck
Originally Posted By: FastLane
You can use iridium plugs in anything you want.

Let me rephrase my question: will it work well?


The short answer here is "Yes, it should work fine"

The long answer is:

Regardless of the type of plug (copper, platinum, double-platinum or iridium), all plugs deliver spark essentially the same way, and they all utilize a copper core. The difference in 'type' is the electrode material and how well it holds up over time, stays clean, etc..

The major difference here being - how long the plug can stay in the engine and continue to deliver a good spark. Iridium is incredibly durable, and is very good at self-cleaning, so it last a LONG time, as evidenced by the 300,000 on these plugs, and the factory iridium plugs I took out of my Fusion @ 215,000 miles (which still looked pretty darn good).

As a rule, Iridium is not any better at conducting electricity or delivering a strong spark than Platinum, which is no better than nickel, etc.. Given plugs for a specific application SHOULD all deliver spark equally in that application, when new.

So yeah, iridium should work well.

 

[Vikas]

Assuming the iridium plug matches the reach and heat range and gap etc i.e. it should be listed officially as substitute by the manufacturer.

 

[SubLGT]

Originally Posted By: demarpaint
That's pretty impressive. You're lucky they came out w/o problems.


Those Denso plugs look like they have an anti-seize plating on the threads (like NGK).