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3.4 spark plugs?

Discussion in '1st Gen. Tacomas (1995-2004)' started by 01GreenTacoma, Nov 26, 2017.

  1. Nov 26, 2017 at 8:18 AM
    #1
    01GreenTacoma

    01GreenTacoma [OP] Well-Known Member

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    I did a valve cover repair and spark plug change yesterday. First time I've ever changed them. What I found was dual denso plugs in the drivers side with single NGK on passenger side. Is this normal?? The plugs were extremely worn.
     
    Running Board Man likes this.
  2. Nov 26, 2017 at 8:20 AM
    #2
    Sodom

    Sodom Well-Known Member

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    Yes, that's how they came from the factory. Mine were like that as well when I just changed them at 180k.

    EDIT: I'm sorry, both are dual electrode.
     
    Last edited: Nov 26, 2017
  3. Nov 26, 2017 at 8:21 AM
    #3
    TACO TX

    TACO TX Well-Known Member

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    Yes it's normal for all Tacomas from the factory.
     
  4. Nov 26, 2017 at 8:22 AM
    #4
    Mobtown Offroad

    Mobtown Offroad Boss

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    Yup. When I changed mine I went dual Denso in all 6.
     
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  5. Nov 26, 2017 at 9:09 AM
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    vettehigh

    vettehigh Tacoma Tank

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  6. Nov 26, 2017 at 9:14 AM
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    Blkvoodoo

    Blkvoodoo a Hooka smoking caterpillar has given me the call

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    38k on NGK
    IMG_0545.jpg
    Denso went back in
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    233k on 4Runner 3.4
     
  7. Nov 26, 2017 at 9:18 AM
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    vettehigh

    vettehigh Tacoma Tank

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    I went by the manual...not to mention, mine had 5 Autolite plugs mixed with one Bosch plug plus Pep Boys plug wires. Went with NGK (TE66) wires too
     
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  8. Nov 26, 2017 at 9:23 AM
    #8
    QMEDJoe

    QMEDJoe Proverbs 3:5-6

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    can’t remember why they did that. Someone on a thread awhile back explained why it was Densos on one side and NGK on the other. :notsure:
     
  9. Nov 26, 2017 at 10:45 AM
    #9
    01GreenTacoma

    01GreenTacoma [OP] Well-Known Member

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    Yea I had heard Denso and NGK mix before but never single and dual mixed. I meant to take pictures but forgot...
     
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  10. Nov 26, 2017 at 11:02 AM
    #10
    Sodom

    Sodom Well-Known Member

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    I think it might be because different sides of the engine were manufactured in different locations.
     
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  11. Nov 26, 2017 at 11:18 AM
    #11
    Dirty Pool

    Dirty Pool FLIES ON THE FRIES, KETCHUPS WATERED DOWN

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    Dual electrode Denso and NGK from factory yes, single electrode no.
    The "most" likely reason for the factory mix is a business practice known as "Vendor Management" and the fact that Toyota owns a huge chunk of both Denso and NGK. There are no performance, operational or assembly theories that hold any water.

    There are a couple things to note on "reading" these plugs. The NGKs from the factory and even some from aftermarket sources came "pre gapped" wrong. For a time NGK even listed the gap wrong, much smaller than the Toyota spec that the Densos came properly set with. IIRC it (NGK) was something like .023" with Toyota spec at .043".
    In addition one side of the 3.4 fires center to ground while the other side fires ground to center. This can contribute to the perceived erosion and promote a bit of false "brand loyalty".
    Below are the factory plugs form my truck at 30K. The Densos show a larger gap and much more erosion on the center electrode.
    [​IMG]
     
  12. Nov 30, 2017 at 12:32 AM
    #12
    Djmjay2

    Djmjay2 Member

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    I just purchased a 2003 and plan on changing the plugs which ones do I choose? Seems like they have to be dual electrode? I was considering the new Denso long life iridium IK16TT long life but I'm pretty sure they're single electrode even though Denso claims they're fine. Do I buy all 6 of the same?
     
  13. Nov 30, 2017 at 4:57 AM
    #13
    TACO TX

    TACO TX Well-Known Member

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    Standard copper generally perform best, yes they have to be changed more often but IMO from my 03 it ran best with standard copper over the higher end plug. Yes all y will be the same. All Tacomas come half Denso/NGK but you can get the Denso at dealership cheap.
     
    Last edited: Nov 30, 2017
  14. Nov 30, 2017 at 5:36 AM
    #14
    01GreenTacoma

    01GreenTacoma [OP] Well-Known Member

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    I got my new Denso plugs from Toyota. They were like 2-3$ a piece
     
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  15. Nov 30, 2017 at 5:43 AM
    #15
    TenBeers

    TenBeers Well-Known Member

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    Yeah.
    As the engine is moving down the assembly line, there are workers on both sides with tasks to do. They each have their own parts supply next to them. Whatever they stock them with is what gets put on that side. You do want to have more than one supplier, but some engines may still get all NGK and other get all Denso, some get a mix.
     
  16. Nov 30, 2017 at 7:42 AM
    #16
    ThunderOne

    ThunderOne Well-Known Member

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    Same, I have never heard of duals being on one side and singles on the other. That’s not right. Someone else must have swapped one side.
     
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  17. Nov 30, 2017 at 9:13 AM
    #17
    01GreenTacoma

    01GreenTacoma [OP] Well-Known Member

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    When I got got th truck in 2003 it had 26k on it and no work had ever been done to it other than the oil changed. To the life of me I can not think of a time I would have had someone work on the engine other than the timing belt and water pump. Seems weird they would have only changed one side though....
     
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  18. Dec 1, 2017 at 9:37 PM
    #18
    Scatch

    Scatch Member

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    6 Densos came out, 6 Densos went back in. Never had a problem. NGK wires though.
     
  19. Dec 1, 2017 at 10:03 PM
    #19
    INSAYN

    INSAYN Well-Known Member

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    My 1997 had 181k miles on it when I finally decided to change them, and the wires due to reduction of mpg's.
    Went from consistent 18-19mpg, down to 16mpg over a course of about 20k miles or so.

    3 Densos and 3 NGK came out, 6 NGKs went back in.

    At 218K miles now, getting 18-19 mpg.
     
  20. Dec 1, 2017 at 10:10 PM
    #20
    marinetaco

    marinetaco Well-Known Member

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    Were the singles on the passenger side? Was there a white mark on the tip of all 6? I'm thinking if the 3 singles were in the passenger side, they were changed out because they were easier to access.
     

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