Does anyone know why toyota put ngks on the right bank and densos on the left of the 3.4 liter? Toyota doesnt know why. Maybe someone here knows. I sure dont know. Do you??

 

It's pretty common, but I have never heard a definitive answer as to why. Some have said that the plugs have different conductivity to offset the different distance of each bank from the coil packs, others have argued different heat ranges, but then you replace them all with one brand, all is well...

 

Another toyota mystery i guess. Thanks WATRD

 

Someone at Toyota is obsessive compulsive? Another of life's little mysteries...

 

I heard it had to do with the heads being assembled in different locations. Who knows?

 

Mine were all NGK

 

I heard it had to do with the heads being assembled in different locations. Who knows?

 

I would agree that it is from two different plants making and assembling the heads

 

well. I replaced the plugs with all denso plugs. They were the cheapest at Toyota by far. Cheaper at Toyota??? Go figure!!