Iridium plugs in a 2nd gen 6

Good lord people You do know that iridium plugs are copper except for a tiny nib that the spark jumps.

If you notice any improvements it is because the old plugs were worn out. Copper plugs would give the same effect, but it won't last a long.

Physics tells you that as far as the ignition system is concerned the two plugs are identical. I measured the properties of copper and iridium plugs with a 20,000 count meter (ie damn accurate) and they were for all practical purposes identical.

Because I have better things to do with my spare time than doing pointless tasks I went with the iridium.

 

The same reason I went with Iridium. I have a 2004 2.7 and it had copper stock. copper is actually the best material for plugs out there as far as conductivity is concerned. Platinum and iridium don't work any better and probably aren't even as good but no daily driver is going to feel the difference. I went with iridium because I don't want to "have" to change plugs every 30,000 miles. No difference at all in performance or fuel mileage after I changed and the coppers had 30,000 miles on them and were due for a change at the time.

 

I did the NGK Laser iridium plugs in my 12' 4.0L Been over a month and no problems. I did not notice any better performance but no issues either. If it saves my need to change plugs for a long time then worth it.

 

That's not why supercharged motors use iridium plugs. Supercharged applications need colder spark plugs to prevent predetonation and spark knock, aka "pinging". Iridium plugs are cooler plugs and thus recommended.

 

Such misinformation, how hot or cold a plug is is determined by the length of the plug not if it has a tiny little nub of iridium on the end of it. Iridium plugs are 99.9999% identical to a "copper" plug. Here are some pictures to show the difference.



That little .6 mm nub of iridium isn't going to make a bit of difference to the ignition system or how hot or cold the plug is.

This is what determines the temperature of a plug

incase you don't believe me here's a quote from the NGK web site:

 

Duh. The guy I quoted said that supercharged engines use iridium plugs because they last longer, I was simply saying that is not 'why' they use them. I never said that iridiums are the only option. But good for you, you know how to copy paste.

 

The supercharger does need a colder spark plug - which is why it specifies a spark plug in a lower heat range (compare the heat range in the part number compared to the stock 4.0 plugs). Said plugs are available with any tip material - nickel, platinum, iridium. The tip material does not determine the temperature - the heat range of the plug which is determined by the insulator is sets the operating temperature.

 

OOPs sorry. I read your post and responded. I thought you said "Iridium plugs are cooler . . . "

My mistake

 

jesus el chapo christ, we were talking about the iridium spark plugs that Toyota recommends/puts in it's supercharged engines. Alright let's recap

- THOSE plugs are colder.
- They are not colder simply because they are "iridium".
- They are not needed because they last longer but because a supercharged engine needs a lower heat range plug.
- We all love to be right on the internet.

sweet, let's move on

 

Ah - got it - didn't get that from your original post and then I cross posted while you were replying and didn't see the reply until just now!

 

All good, I appreciate your previous reply though in that it was simply informative and to the point, not belittling. Cheers

 

Well, I learned something tonight. I never paid any attention to the Iridiums when I put them in. I just knew they lasted a lot longer. Now I know that plugs are all copper and just coated with various elements. With 40,000+ miles I like the Iridiums. I did pull them once just to check them out at the usual recommended interval and just put them back in. I'll check them in another 40 or 50,000 miles.

 

So did you happen to check / measure the gaps. I'd like to see and hear about the differences after 30-40K miles. The OEMs are just slightly worn after 30k which is why I pushed them to 40K. I'm coming up on 70k now and am leaning toward the Iridium plugs. So far it certainly sounds like to way to go. FWIW on Rock Auto the NGK iridium plug is listed as a most popular item and the standard NGK is not? The Denso standard plug is though Thanks

 

I did check the gap and set them at the factory gap but never measured them from the first time I put them in. They say to never "gap" an Iridium plug. I have no idea why. I gapped mine when new and then this last time when I pulled them out just to look at them. They also say not to use anti-sieze on the Iridiums because the threads have a coating on them that prevents them from seizing. They say this because they say it will throw off the torque for the plugs. The main reason I pulled them to check them was because I didn't have a torque wrench when I put them in and didn't put any anti-seize on the threads. I put a "very" thin layer of anti-seize on them when I re-installed them. You can tell I don't pay much attention to directions sometimes. I figured if I end up leaving them in there for another 60,000 miles I'm not going to take any chances on the threads seizing especially the way they squeaked going in the first time. I can check them from time to time to see if they are coming loose.

 

Yesterday I replaced the plugs with Iridiums. Got them at rockauto.com for about $6 ea along with filters. Got a 5qt jug of M1 oil plus the half qt I already had and did the 30k service at 70k (diff oils were topped of at 60k and looked fine). So the plugs had 40k on them and were worn down quite a bit. The gaps ranged from 0.46 - 0.5 but it ran fine. I waited till 40k because at the first change at 30k they looked fine. Took my time about 2.5hrs for everything making sure the plug change was done correctly. They were gapped at 0.40 so I didn't touch them and on the box it said not to re gap them. Fired right up. Idle settled down just like normal after warming up and runs perfect. I will check one or two 30k from just to see but happy to know I probably wont have to do that again since my mi are below 10k/yr now and I'll most likely be in something else by then. Here a couple of pics. btw cabin filter was a mess - need to do that more frequently since I like to off road. Cheers.

 

OK, I have a follow-up question...I am interested in moving to the Iridiums. How do I know what model number of plug to use to ensure the new Iridium plugs have the same heat range as the original copper-tipped plugs? I will probably go with Denso, but need to know which specific Iridium plug to get.

 

If you do it online or go to an auto parts store you just reference your vehicle and compatible plugs will come up. On rockauto.com many come up including Denso but I chose NGK's because they have always served me well on all vehicles I've owned including motorcycles. Also you can see the most popular ones come up. My truck purrs like a kitten since putting them in.

 

Difference between Iridium and Platinum? Auto store I went to only had NGK platinum plugs available not NGK iridium plugs.

 

Found this using google.
Single platinum spark plugs—a step up from copper spark plugs

Platinum spark plug
A single platinum spark plug is basically styled after a copper spark plug with a platinum disc welded to the tip of the center electrode. Since platinum is harder than nickel alloy, it holds its sharp edge for as long as 100,000 miles. Platinum spark plugs also run a bit hotter, preventing spark plug deposit buildup and fouling.

Platinum spark plugs are usually the best spark plugs for newer vehicles with electronic distributor-based ignition systems (DIS). If your owner’s manual recommends platinum spark plugs, don’t downgrade to copper spark plugs to save money. However, you can upgrade to either double platinum spark plugs or iridium spark plugs.

Double platinum spark plugs—twice as good?

Double platinum spark plug
Double platinum spark plugs were designed for “waste spark” DIS. In a waste spark system, the spark jumps from the center electrode to the side electrode for the cylinder that’s on the compression stroke. To return the electrical pulse back to the ignition coil pack, the spark jumps backwards (side-to-center) on the partner cylinder. Since the partner cylinder is on its exhaust stroke, nothing ignites and the spark is “wasted.” You can’t use single platinum spark plugs or traditional copper spark plugs in these systems because the side electrodes aren’t designed to handle the reverse spark. But double platinum spark plugs, with a platinum disc welded to their side electrode, work exceptionally well. Both the center and side platinum discs remain sharp, allowing sparks to fly easily in both directions without causing rapid electrode wear.

If your owner’s manual recommends double platinum spark plugs, then those are the best spark plugs to use. Never downgrade to single platinum spark plugs or copper spark plugs. However, you can upgrade to an iridium/platinum combination plug (an iridium center electrode with a platinum-tipped side electrode).


On the compression stroke the spark shoots from the center electrode to the side electrode.








On the partner cylinder's exhaust stroke, the spark shoots from the side electrode to the center electrode.

Iridium spark plugs—the best kind around

Iridium spark plug
Iridium is harder than platinum, and in most cases, iridium spark plugs last about 25 percent longer than comparable platinum spark plugs. Because iridium is costly, iridium spark plug manufacturers reduce the diameter of the center electrode to as little as .4mm. In addition to saving money, the “fine wire” center electrode on iridium spark plugs increases firing efficiency.

Many carmakers require iridium spark plugs or iridium/platinum combination spark plugs for (COP) ignition systems. If your owner’s manual specifies iridium spark plugs, don’t downgrade to platinum spark plugs, or double platinum spark plugs, or even copper spark plugs. They won’t perform as well as the iridium spark plugs in this case.

As the spark ignites the air/fuel mixture, the colder side electrode tends to “quench” the flame. To combat quenching, some spark plug manufacturers cut a “U” or “V” shaped channel into the “spark receiving” surface of the side electrode. The larger channeled area reduces quenching and allows the flame to grow more quickly. Other manufacturers split the end of the side electrode to reduce the flame’s contact with the side electrode and allow the flame to shoot straight down into the cylinder.

Are these channeled electrodes the best spark plugs you can buy? There’s no industry-wide consensus on whether these designs work better, but if channeled spark plugs make sense to you, buy them. They’ll perform at least as well as a non-channeled plug, if not better.

When you're ready, here's how to replace your spark plugs and change your spark plug wires.

Pro Tip
Always replace spark plugs before the recommended service interval. Waiting until the full service cycle could cause them to seize to the cylinder head, making removal difficult. In addition, the wear that occurs during the last 20% of a spark plug’s life will cost you far more in reduced gas mileage than the cost of a new set of plugs.