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Best spark plugs for 05 Prius

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by shepdawg, May 14, 2014.

  1. shepdawg

    shepdawg Junior Member

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    Hello all, I am coming up to 120,000 miles on my 2005 Prius. It's my understanding that the spark plugs are recommended to be replaced at that time. I remember reading an article many years ago where someone tested multiple different spark plugs and found some of the multi ground electrode type significantly increased fuel economy (around 8 mpg increase over stock replacement). Any advice would be appreciated.
     
    #1 shepdawg, May 14, 2014
  2. drmanny3

    drmanny3 Member

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    I really doubt that you can find a plug that will give you an increase in mileage compared to the stock plug. There is a lot of snake oil in spark plugs and oil. As long as the spark is sufficient to burn the air/fuel mixture in a smooth manner you are good to go. Extra electrodes in a low compression engine such as the Prius are not going to do much other than cost you more money. What you should do is remove your plugs and note how they are firing. Are they oil fouled or are they burning the fuel well. You should see an even medium tan to dark brown color. If they are black then they have been burning oil. 120,000 miles is a lot of mileage for a plug. Be careful when taking out the plugs to not allow dirt and other stuff to fall into the plug holes. Then hand turn the plugs when you first put them in to insure that you do not strip them. They need to be seated but we are not talking a lot of torque. I am not sure of the specs but hand tight plus 10 to 15 ftlbs of torque. Inspect the connectors to insure they are in good shape. Be gentle.
     
    #2 drmanny3, May 14, 2014
  3. Former Member 68813

    Former Member 68813 Senior Member

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    If you find that paper on MPG increase, let me know. Generally, multi-electrode plugs are considered just a gimmick, but it's conceivable that some users see benefits and some users see drawbacks as every engine model has a different combustion chamber configuration. I recently posted old "news" about a double tipped Denso plug that is energy efficient for sure.

    Fuel efficient spark plug | PriusChat
     
    #3 Former Member 68813, May 14, 2014
  4. JC91006

    JC91006 Senior Member

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    The proper plug for your car is this one:

    NGK (4996) IFR5T11 Laser Iridium Spark Plug,
     
    #4 JC91006, May 14, 2014
    wjtracy likes this.
  5. shepdawg

    shepdawg Junior Member

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    Thank you guys for the info.
     
    #5 shepdawg, May 14, 2014
  6. wjtracy

    wjtracy Senior Member

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    OK thanks I just ordered 4...
     
    #6 wjtracy, May 14, 2014
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Or Denso SK16R11
     
    #7 Patrick Wong, May 14, 2014
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  8. tf4624

    tf4624 Active Member

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    I will say there are plugs that do very well but the system I'm talking about is more than just plugs. Your going to have to get a plasma spark and will need to make and weld the proper plug design. Then of course test it. The ignition module will have be upgraded or changed out to supply the plasma. After that adjusting the fuel ratio and computer is nex. Redoing the fuel mapping to a leaner burn.
     
    #8 tf4624, May 18, 2014
  9. JC91006

    JC91006 Senior Member

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    And what would be the point?

    SM-N900P ?
     
    #9 JC91006, May 18, 2014
  10. tf4624

    tf4624 Active Member

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    Higher mpg. A lot depending on how lean you put it
     
    #10 tf4624, May 18, 2014
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