My experience with installing iridium plugs in V6

Today at 30,200 miles, I changed the plugs in my 09 4.0 for the first time. I used Chris' writeup as a reference. Excellent guide as always. Took me a little over an hour. It was the easiest spark plug change on a modern car I've ever done.

Stock plugs looked good. Densos looked better than the NGKs. If I was replacing with the stock copper plugs, get the Densos for sure!

I decided to get NGK laser iridiums to replace the stock copper plugs (purchased from Amazon, link on bottom). I read the "warnings" about iridiums but figured even if I don't gain power (or even if I lose a HP or two) the extended change interval would be worth it. It's not that I don't like wrenching on my truck, but sometimes it's tough to find time to pull off maintenance in the winter, etc. I hope the plugs will last 100k, but I will check them in 50k or so.

First impressions- startup is quicker than the stock plugs at 30k. Acceleration around town is a little smoother. In the upper revs it's basically the same. No noticeable loss or gain of power when I dog it, but smoother for sure. No CEL, nothing out of the ordinary.

If you're thinking about it, consider this as a "success" story.

Amazon-

$11 NGK (4904) ILFR6T11 Laser Iridium Spark Plug, Pack of 1

http://www.amazon.com/gp/product/B001MU29LA/ref=oss_product

 

more efficient spark less resistance.....iridiums for the win

 

First good thing I've heard about iridiums in the 4.0.

 

It would be good to know of any other good things about the iridium plugs in the 4.0 V6. It would be nice to only change plugs every 100k . But is sounds like more cons than pros on the iridium plugs. Lets here some more.

 

I can find time to change mine every 30K with the densos.

 

so you paid over $50 for iridium plugs instead of $20 for stock plugs from the dealer?....

 

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Good info here ... I am planning a plug change early ... maybe at 25,000.

Not using "NGK Laser Iridiums" here ... however deciding if "Dyson" is better than "Denso" or should I use "Hoover" ...
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I purchased the ikh20 and just finished the install a few weeks ago. The things I seem to have notice was a better start and smoother acceleration, but that could be the case of the older plugs being used up vs a new plug. Though the one thing I can add is that I got an increase miles per gallon from averaging 290-300 miles a tank to 300-320 miles. Not much of an increase but I do notice that the past few weeks going to work my fuel light doesn't light up at the end of the week. I can make it to the gas station before it lights up now. Than the other question could it be because after 30k miles the engine started to break in properly? I don't know and yet to know. There are alot of factors but so far it seems to be a good value at 60 dollars for 6 vs 24 follows for 6. Including a longer lasting plug. But who knows it's still to early.

 

I had Iridiums in my old 3.4L. Pulled them at 60K. Two plugs were worn down to the nub. Although I didn't notice any performance lose.