Iridium plugs in a 2nd gen 6

It would, however knock sensors retard the spark only after knocking or pinging has happened (that's the "knock" they sense), and continue to keep the spark retarded for some period of time afte the event--not exactly what one wants for bleeding edge performance. In fact when building balls-and-all high performance engines knock sensors are one of the first things to go--tuning the engine to the edge, but not knocking, is preferable to careless tuning and letting the ECM retard the spark fro some period of time because it "heard" one ot two pings

 

The other thing I've "heard" (meaning could be completely wrong) is that fine wire plugs can also end up with a higher tip temperature at high boost than a fat wire plug would which can cause pre-ignition. That's obviously not an issue with a Tacoma though.

And thanks for your very informative post!

 

It was commonplace "way back when" in the days of crappy ignition systems (Kettering systems using "points", condensors, coils, distributors, rotors, wires and all that antiquated junk) to use plugs of one or two or even three heat ranges higher on f/i engines--as a kludgy way of compensating for the low voltages the crummy ignition system supplied (getting 20 kV to the plug was a big deal).

A lot of that old time "conventional wisdom" persists and if someone put fine wire plugs of such a higher heat range in an f/i engine with a modern ignition system¹ it could very easily result in a glowing ember of an electrode.

But with a plug of the proper heat range why would a small mass of a electrically and thermally highly conductive metal (the "tip" in a platinum or iridium plug), retain more heat than a significantly higher mass of a relatively poor conductor (the tip of a nickel/chrome alloy plug)--doesn't make sense. The truth always makes sense, I used to to my daughters that all the time when they were teenagers.

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¹ - Modern coil-pack and Coil-On-Plug (COP) ignition systems can easily deliver 40 kV to 55 kV directly to each plug.

 

Yeah, that was sort of my thinking when I first read it. If you are at the same heat range it doesn't seem like tip diameter should have any significant impact.

If anything I'm guessing the folks who asserted that (can't find it now, but think it was from some engine tuning data from a race team that ran both plug types of the same heat range) were reading the data "backwards" as it were. If the fine tip plug was causing spark advance that in itself would be increasing the plug temperature and then leading to pre-ignition. Basically they came up with the wrong "narrative" to explain their data. What you already stated - slight increase in spark advance with the fine tip - would explain their data on its own.

Thanks for the clarification!

 

I'll be installing Autolite iridium plugs (been very pleased with them) at my first change, in 20k miles or so, the dealer I bought from in October installed a new set of conventional plugs before I bought it...

 

Better spark, more efficient.
I don't get it, iridium plugs are better and last longer.
They are also copper plugs, just the tip is iridium.
Just replace mine after 2 years and they still looked good.

 

Yup. Most all contemporary automotive spark plugs have copper cores...

 

Great thread, getting ready to swap my plugs. Thanks everyone for the input, especially Cliff.

 

I this previous post I promised to come back after the first tank of gas with a report. <drum roll .....> Not much difference. Gas mileage went from 17.0 mph on the old plugs to 17.9 mpg with the iridium plugs. I drove as I always do, mostly city with the odd stretch of freeway now and then. However, there are a lot of uncontrolled variables like the brand of gas changed, the pump was different, the weather was warmer, the plugs were gapped correctly vs the old ones, so I'm not getting too excited about a .9 mpg increase. With all of those variables any one or a combination could explain the difference.

Iridium plugs certainly don't hurt gas mileage and in the long run they save money and precious weekend time. I'll pop out one of the easy to get to iridium plugs when they hit 60K miles just to see how its doing, but if it looks OK it's going right back in for another 40K miles.

Bottom line - I can see no reason whatsoever to run plugs that have to be changed every 30K miles, none.

 

I run precious metal plugs (Autolite iridium mostly) in every road vehicle we own, and highly recommend them unless there is some legitimate reason for not using them.

Nonetheless and FWIW just replacing conventional plugs with 40k on them would account for some of the mpg increase.

 

A tuneup is never a bad thing. But my main reason for wanting the iridium plugs is because I'm pretty much like this guy with my weekend time.

 

Still liking the iridium? Thinking of getting some NGK iridium for mine.

 

So far so good. My last tank was 17.6 mpg. So, as expected the value of iridium plugs isn't some crazy power claim, but in hours of saved weekend time. I have no knowledge of the NGK plugs, but I'm sure they are fine. I mean really how much different can one plug be from another?

I looked at my previous posts and noticed I didn't post the plug I went with. So here's an Amazon link to the plugs I purchased https://alexa.design/2osVDl3 Denso (4704) IKH20TT Iridium TT Spark Plug

 

Autozone had the NGK LFR6CGP platinum plugs in stock instead of the

$10 LFR6C11 NGK (7787) LFR6C-11 V-Power Spark Plug, Pack of 1

LFR6C11. They're computer showed it as OEM or better replacement.

Thoughts? They're going in in a couple of weeks

 

Installed a New set of NGK 4904 Laser Iridium Spark Plugs in my 2013 4.0 V6 Tacoma yesterday, noticed quicker start, quieter and smoother idle and throttle response, a few more mpgs after driving 200 miles, Love the new Plugs! Dont beleive all the negative whinning and complaints! try for yourselves ,if dont like,then, switch back to the cheap plugs! I Love the Iridiums! NGK or Denso are both GREAT!

 

It seems like everyone here has 6's. I don't know about those but I have a 2.7 and at 120,000 I got rid of the stockers and installed Iridium plugs. Don't remember the brand but since I never buy cheap junk for my vehicles I'd bet they were NGK's or Denso's. In any case, I noticed no improvement in fuel mileage at all and noticed no improvement in performance or idle at all. I installed the iridiums for one reason. They will last 100,000 miles and I don't want any extra maintenance if I can avoid it. I did pull them after 30,000 but only because I didn't have a torque wrench when I installed them and now I do.

Also, as far as leaving them in there for 100,000 miles? The ones I bought distinctly says in the directions NOT to use any type of anti-sieze because it will throw off the torque specs. NGK has a special coating they put on their threads to stop any types of corrosion or "sticking" to the head. When I did mine the second time I did use a very small amount of anti-seize anyway and then torqued them down. No problems since. They are at another 30,000 right now and the truck still runs the same as the day I put them in which is the same as it ran before I replaced the stock Denso's with 30,000 on them. I'll probably pull them again in the near future just to check them out but it's nice to know that I don't have to if I don't want to.

That's the main reason to use iridiums. If you want performance and the best mileage copper is the way to go unless your engine requires iridium. Platinum is right between the two I suspect and probably gives the best of both worlds.

 

When it comes to plugs, sometimes cars can be finicky. I choose to stick with OEM in terms of material on all my cars. That means copper for the Tacoma, iridium on the GTO. No issues so far. Both cars are super easy, and a full set can be done in under an hour. It gives me an excuse to hide away in the garage for a bit and have a mid day beer too.

 

I suspect you're right and the thought of going back to the copper stockers has entered my mind but I want something that will keep working when I'm lazy. Which hasn't been the case yet. Go figure.

 

I worked in a shop for a while and saw all the oddities and pissed off customers that came with it (whether it was their request or not lol).

I've even seen it by brand. I've seen Chevy's with issues on NGK, but do fine with AC Delco. Toyota issues with Bosch, none with Denso or NGK, etc etc etc. So not only do I stick with OE material, I'll usually use OEM stuff too. Even if it costs a few bucks more. I replaced the iridium in the GTO at 90k (rated for 100) with the same AC Delco plugs. Not one issue (at 121k now). I just picked up Denso plugs at the dealer for the truck (Autozone would only source Bosch, not NGK).

 

I don't have a 2.7 motor, but was curious about this. It's my understanding they come from the factory with Iridiums. I browsed thru a soft copy of a 2015 Tacoma Owners Manual and sure enough, the 2.7 uses Denso SK20HR-A11 - Iridium.

Maybe earlier 2nd Gen 2.7s used copper. I don't have all 11 owners manuals to sift thru. Did you remove copper plugs or Iridium plugs?