Results 1 to 9 of 9
  1. #1
    Moderatrix mojo jojo's Avatar
    Join Date
    Jul 2009
    Posts
    425
    Like
    0
    Thanked 0 Times in 0 Posts

    DIY: change spark plugs (Yaris)

    Well I changed my spark plugs today; here are some pics of the procedure.

    Tools needed:

    • socket wrench handle
    • 10mm socket
    • 17mm deep socket
    • 6" extender
    • magnetic 'wand' to lift plug from hole


    For safety's sake first unhook the negative terminal on the battery using 10mm socket. Remove engine cover. Now we're looking at the 4 ignition coils.





    Undo the wires--you have to press pretty hard on the back of the clip and pull to unhook.




    Remove the bolts using 10mm socket




    Remove ignition coil to get at plug beneath--do each spark plug one at a time.




    Using extender and 17mm deep socket, unscrew the plug.






    Use your magnet to lift the loosened plug out of the hole--I use a magnetized telescoping flash light




    Place the new plug in tip of the coil insulator. Use it to lower the plug into position and tighten it a couple turns. Finish tightening with your deep socket.



    Finish by reinstalling ignition coils one at a time. Reinstall bolts and re-hook wires. Reconnect battery. Start car and yay you're done

    A final step is to inspect the old plugs for oil, damage or colored deposits--these ones are pretty easy to read, all that red on the nose is from the octane booster I use all the time.

  2. #2
    Sean Advocate's Avatar
    Join Date
    Sep 2009
    Location
    San Jose California
    Posts
    1,150
    Like
    0
    Thanked 0 Times in 0 Posts
    great DIY mojo, thanks

    also like how you mentioned to inspect the old ones for residues.

  3. #3
    §†ęĄ¶‡Ћ-NCP96 id3379's Avatar
    Join Date
    Mar 2010
    Location
    San Diego, CA
    Posts
    231
    Like
    0
    Thanked 0 Times in 0 Posts
    You forgot you should always pre-gap the plugs. There are plug boxes that say "pre-gapped" but think about how many of the same cars use the same size plug, how do you know which car it was gapped for ? they have all different gap lengths.

  4. #4
    Moderatrix mojo jojo's Avatar
    Join Date
    Jul 2009
    Posts
    425
    Like
    0
    Thanked 0 Times in 0 Posts
    You're right, I did not set the gap, and in fact have no clear idea what might be the optimal setting.

    The spec for a new plug is 0.039 to 0.043 in. I read somewhere that because I'm boosted I should reduce that gap to make sure the denser fuel/air mix ignites. But then I read something else that said a wider gap creates a larger spark and burns the fuel/air more efficiently. So its confusing.

    Since I'm not getting any symptoms of improper gap like pre-ignition/detonation or misfires/fouling on plugs, I have frankly felt reluctant to mess with it. Buuuuuut since I'm changing these 2-3 times a year now I really ought to experiment on fine tuning.

  5. #5
    §†ęĄ¶‡Ћ-NCP96 id3379's Avatar
    Join Date
    Mar 2010
    Location
    San Diego, CA
    Posts
    231
    Like
    0
    Thanked 0 Times in 0 Posts
    Quote Originally Posted by mojo jojo View Post
    I read somewhere that because I'm boosted I should reduce that gap to make sure the denser fuel/air mix ignites.
    I was completely unaware that you were boosted (sorry), and your correct about your gap being slightly different since you are boosted and running a piggy back system.

  6. #6
    Moderatrix mojo jojo's Avatar
    Join Date
    Jul 2009
    Posts
    425
    Like
    0
    Thanked 0 Times in 0 Posts
    no no you make a great point its a general purpose diy so its important to be aware of and I left it out because I haven't been doing it...maybe you could make a diy on how to gap a spark plug? I think it would be very useful.

  7. #7
    §†ęĄ¶‡Ћ-NCP96 id3379's Avatar
    Join Date
    Mar 2010
    Location
    San Diego, CA
    Posts
    231
    Like
    0
    Thanked 0 Times in 0 Posts
    Quote Originally Posted by mojo jojo View Post
    no no you make a great point its a general purpose diy so its important to be aware of and I left it out because I haven't been doing it...maybe you could make a diy on how to gap a spark plug? I think it would be very useful.
    I will make one tomorrow

  8. #8
    Junior Member
    Join Date
    Jun 2012
    Location
    UK
    Posts
    1
    Like
    0
    Thanked 0 Times in 0 Posts
    Hello, this is a very useful post, as a keen DIY person, I wanted at least to remove my plugs, check them out and replace if not done by the last service agent. At lease I will know they have been done!! It is an interesting dialogue about the electrode gap. If you look at a UK site selling various brands for the 1.3VVTI model here: http://www.onlinecarparts.co.uk/car-...park-plug.html you will see that the standard seems to be 1mm, but if on LPG you need 0.7 to 0.8 . Now if you have a plug spanner with a rubber insert to grip the plug, BEWARE it is not a cheap far-east make, as the rubber insert can have a high metal content, and leave a line on the white insulator, that you just will not see. When you start to get misfires, you just cannot believe that your new plugs caused it!! I scratched my head for a week when I last worked on my old Ford Focus, and caused a track-line on TWO new plugs because of a bad quality spanner!! I had to use some special "magic foam" off the wife to remove the tracking, but ensured a good defense against flash-over with some high-voltage silicone grease rubbed around the insulator. It appears that the Yaris plug is covered very well from rain and water ingress, so as long as I don't mark the insulator, I probably don't need to worry about using Silicone Grease. TD

  9. #9
    Junior Member
    Join Date
    Apr 2012
    Location
    SoCal-San Gabriel
    Posts
    1
    Like
    0
    Thanked 0 Times in 0 Posts
    I know this is a older post but,
    Thanks for the do it yourself thread,
    Made it easier than I thought.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •