Spark plug choices

[Suey 1958]

I have 235k miles (2007 hatchback) on original plugs and still runs perfect but want to change them. The guy at auto zone said the cheap 3 dollar plugs won't do the job and iridium plugs are a must. If that is true, then I will buy the 10 dollar iridium's. Not sure if that was a sales pitch or if iridiums are really necessary. Thanks

[bronsin]

Not necessary at all in my experience. We have a tech day for Honda ST 1300 motorcycles and we change a lot of plugs. One guy with 35,000 miles on his iridium equipped ST found a damaged iridium plug. Not sure how it got damaged. Another guy from Columbia with 75,000 miles on his bike have the original conventional plugs. We went to honda to get new ones but they didn’t have any. So we just carefully gapped and reinstall the old ones. Machine ran like a watch.

[NYC-SE]

The Yaris is spec'd for iridium plugs. DENSO SK16R11 or NGK IFR5A11, as per the manual.

[sh0rtlife]

personaly ive found a few things with plugs...
NGK on euro/jap/bike
champion on small engine/american older stuff and BIKES
autolites are hit n miss at best..cheep plug you toss in something your selling
bosche seem to only work well in volvo/MB/bmw and some audis..but not most vw's

as far as the iridums go...they work well on modern engines not so much on "old" stuff...that said i noticed an improvement when i changed the yaris plugs at 100k

but ive only ever found issues with BRAND vs make/model not so much what "type" of plug it is

[mitch9521]

Denso or NGK only. I change mine every 60,000 miles or so.

[bronsin]

I would definitely NOT Be spending $40 plus on a car with 235,000 miles on it. Go with the three dollar plugs for $12! YEAH !

Then leave them in there for 100,000 miles. I change the plugs on my wife’s Camry at 150,000 miles it didn’t make any difference at all cost $40

The plugs I took out were excellent condition. I couldn’t bear to throw them out.

The only thing I recommend about changing spark plugs is take them out every 30,000 miles or so and clean the threads. On my wife’s Camry I left them in for 150,000 miles and when I try to take them out they were stuck. To get them out I had to start the engine and remove them with the engine hot. Than it was easy

[Suey 1958]

Thanks for the input. I think I will go with the 12 dollar set.
Anyone know what the gap should be on those?

[bronsin]

These will only sent you back eight dollars

Actually the the autolights Are only $1.10 apiece!

Gap is ..44

https://www.rockauto.com/en/catalog/toyota,2007,yaris,1.5l+l4,1433326,ignition,spark+p lug,7212

[Suey 1958]

Thanks Bronsin, I appreciate the info.

[remcafee]

yikes, im worried about all the bad advise going around, the 1nzfe is made for iridium plugs, nothing else, period!

[WeeYari]

yikes, im worried about all the bad advise going around, the 1nzfe is made for iridium plugs, nothing else, period!

Why exactly do you say that? I ran old school Champion plugs for a couple years. Honestly didn't notice a lick of performance or fuel economy differences compared to the iridium.

[remcafee]

because you run the risk of increasing carbon in combustion chamber, worse fuel economy, power, the 1nzfe was tuned and calibrated to run iridium spark plugs that can take high heat from fairly lean afrs like the 1nzfe, you could be ok with your champion plugs now, but in reality you technically are not maximizing the life of your engine

[remcafee]

oh yeah and not to mention that iridium is more conductive than copper so it takes less voltage to spike and fire the spark, so you are also prematurely wearing out the ignition coils

[bronsin]

oh yeah and not to mention that iridium is more conductive than copper so it takes less voltage to spike and fire the spark, so you are also prematurely wearing out the ignition coils

An interesting theory. Can you quote a source on that?

[thetut]

https://www.championautoparts.com/Parts-Matter/automotive-repair-and-maintenance/Spark-Plug-Materials.html

[bronsin]

Thanks for the input. I think I will go with the 12 dollar set.
Anyone know what the gap should be on those?

Yes you can set a .44 gap on those plugs.

But I’m pretty sure you can’t gap Iridium plugs without damaging them. That is if you find the gap on your iridium plugs much greater than .44 bending the plug will damage it.

[bronsin]

dear thetut

That was an interesting piece. But it didn’t explain why copper core plugs will wear out your coils. I also didn’t get from it why copper core plugs would cause premature engine wear

[thetut]

More research required but I'm too lazy.

[remcafee]

An interesting theory. Can you quote a source on that?

its pretty simple basic electrical theory, you will change the flow (resistance) of electricity with different conductive materials. the ignition coils store and spike voltage specifically for iridium spark, think of it as a magnet, a magnet sticks worse and better with different metals

[Compeer]

its pretty simple basic electrical theory, you will change the flow (resistance) of electricity with different conductive materials. the ignition coils store and spike voltage specifically for iridium spark, think of it as a magnet, a magnet sticks worse and better with different metals

Yeah I actually have coppers in my car but will go back after reading up more about them. The older platinums are straight up worse than copper but last longer. The iridiums provide better performance at lower amperage and last longer and are more resistant to melting.

In saying this all the race engines use copper in the 1nz-fe but they do not care about longevity of stock parts or fuel efficiency.

I read this below and it enlightened me some :biggrin:

https://www.enginelabs.com/engine-tech/ignition-electronics-efi/the-great-spark-plug-debate-separating-fact-from-opinion/

I think I will get NGK BKR6EIX-11 online, the are one step colder but still listed for 1nz-fe. I like to rev it and want to track it one day so this is a good choice for the "spirited driver" who does not live in a very cold location.

[bronsin]

Interesting to know all of this. Of course with hundreds of thousands of miles on the car you really arent concerned with longevity

[Compeer]

Picked up a set of NGK BKR6EIX-11 from market place of course! $60 nzd for the set guy wanted $80 lol im terrible...but why pay full price when if you check marketplace someone is probably selling some cheap they don't need? had been listed 6 weeks..easy haggle! hahaa