Soooooo..OEM plugs......4.0L ?

What is the reason for the factory to install....

3 Denso plugs on one bank........3 NGK plugs on the other ?

Changed my plugs today on my new to me '14 Taco V6.......

Yes....70K miles.....they were S H O T ............

 

One theory is Toyota does this as a way to show Denso and NGK they are each getting 50% of the business.

 

well known and well documented.... thousands of results if you search for "toyota ngk and denso".... been over 20 years of toyota doing this. They have a contract with both NGK and Denso so they split the plugs on each bank of cylinders. Also makes it easy to determine that plugs have never been changed.

 

yep..I figured mine were OEM before I pulled 'em.........

but used 6 new Denso.........

 

Yeah discussed to death in the how-to thread: https://www.tacomaworld.com/threads/how-to-spark-plug-change-1-gr-fe.30479/

Did you measure the gaps on the removed plugs? Did the NGKs consistently have larger gap?

 

in the trash.........maybe I'll measure two for schidts & grins........

 

real close the same..........

.056"

 

Toyota is partial owner of both Denso and NGK, but only Toyota knows why only the Taco's, from what I've seen, have both brands plugs installed. Our Lexus ES350 3.5 V6 did not have both brands, nor did any of our other Toyota products, only the Taco.

 

My 04 Highlander only had 6 Denso Iridium's. The Tacoma had the NKG/Denso split.

 

I was under the impression the heada were built in different locations then shipped to the assembly plant it was just easier for toyota to source NGK's at one plant and Denso at another. I've also heard that it was to help tell left and right heads apart during assembly so the wrong head wouldn't be accidentally installed on the wrong side of the block.

No one knows for sure, but a few 3.4's I've seen have been this way as well at the 4.0's.

 

Aliens

 

Who's on first?

 

Maybe the engine factory is on a border and it's like an East / West thing.

Like hey we use NGK in Japan east... and Denso in Japan west!

 

Not just the Taco's. My 4.0L Tundra was the same way. When I did the plugs I used the same plugs 3 Denso and 3 NGK's. I've worked on a few FJ's and older 4 Runners (03-05's) that were exactly the same. It is my belief that all Toyota 4.0L V6 engines are this way. EDIT: I'm not sure about the newer dual VVT- 4.0L, just the single VVT 4L like our Tacoma's have.