Wrong plugs in my mini-beast

I do plugs all the time at work and they aren't all one or the other...they are 3 & 3

 

Don't bring logic to this octane bashing boom tale.

 

Oh, I meant that would be the manufacturer.
Ya, the 4.0, and even my '03 Tundra 4.7, had NGK in one side and Denso in the other.

I thought the reference was to the 4.0 being copper and the 2.7 being iridium... but they are all either NGK or Denso plugs.

Not sure I buy the different assembly location though. Pretty sure the plugs go in after the heads go on. They most likely go in after the cams are in and valve covers are on, and the cams and covers can't go on until the engine is assembled to the block.
What makes more sense is Toyota has contracts with both companies so they aren't stuck if one has a production problem.
Best way to be able to provide their suppliers with projected usage and avoid confusion on the production line is to simply use a 50/50 mix on the "V" engines.
If supply becomes an issue, the other supplier can ramp up to compensate, but Toyota will already have stock to use until the accelerated shipments come in.

 

Makes sense...I got my 2¢ from a Toyota Hawaii tech guy...either way it's odd but doesn't effect performance

 

Now, copper in one bank and iridium in the other might get interesting around 50k

 

The problem is not the plugs the copper ones would run 60K or more in a V6 it's all about the emission warranty. If you want to protect that you'll have to change the plugs at 30K it's a lot cheaper then buying cats. Toyota can deny the warranty if you show up with plugs that have not been changed. Can this happen? Don't know but Toyota thinks it can and that is the reasoning behind the 30K change.

 

The problem is not the plugs the copper ones would run 60K or more in a V6 it's all about the emission warranty. If you want to protect that you'll have to change the plugs at 30K it's a lot cheaper then buying cats. Toyota can deny the warranty if you show up with plugs that have not been changed. Can this happen? Don't know but Toyota thinks it can and that is the reasoning behind the 30K change.

 

I wonder if this is to prove that the plugs have been changed at the 30K mark if any thing goes wrong.

 

No way to prove it hasn't been done.

We've had more than a few members here on TW source the same plugs when they changed, assuming that Toyota had a good reason to do so.

 

I guess my point is who is going to buy two different brand plugs for each bank?

 

Some people actually do.

I don't see the logic in it, but quite a few TW members have indicated that they do so.
It's no way for Toyota to prove that the work wasn't done.

 

still trying to figure out how iridiums became viable in the 4.0 when I have read NOWHERE in Toyota literature that that is true.

lots of confusion around here.

simple way to change spark-plugs correctly: go to dealer, give vin# for truck, ask for spark plugs. if you think they are too expensive, get denso/ngk part# and source otherwise. correct plugs. no worries. no boom

 

No, but all the original spark plugs that come on the engine when they are assemble are marked on the terminal.

 

#truestory usually is white

 

I read somewhere it had to do with some Japanese law involving fair competition or something like that. Both suppliers plugs are used but you can use either plugs.