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Spark Plug change - engine misfire

Discussion in '3rd Gen. Tacomas (2016-2023)' started by john003, Nov 15, 2024.

  1. Nov 15, 2024 at 7:01 PM
    #1
    john003

    john003 [OP] Member

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    hi everyone I decided to do my spark plug change today. I waited till 75k bc I was a bit hesitant to do it myself, but a few YouTube videos helped me out.

    my issue is that once I start up the truck my engine starts shaking in idle and when I’m going very slow. I was not getting any check engine light even after driving it for a few miles. I was hoping it would pop up so I can scan it and see where im misfiring. What could be my issue here?

    I got the Denso Spark Plug Iridium TT - 4705 off Amazon. And I did not gap them due to it saying it’s pre-gapped and others saying they don’t gap them. Also when tightening them I got them hand tight, and I did just a bit less than a 1/4 turn.

    Thank you for any help guys:(

    Update 11/18: It’s all good now. After a few days trying to solve this issue I had to take it into the dealership. Turns out it was a bad damaged/bad pcv valve hose and it wasn’t plugged in all the way. I messed it up while changing the 6th cylinder plug and never noticed. (It’s the one covered by the foam piece) Oh well at least I’ll always remember this. I appreciate for all the help!! I hope anyone who sees this learns from my mistakes haha.
     
    Last edited: Jan 3, 2025
    SouthFLTaco likes this.
  2. Nov 15, 2024 at 7:34 PM
    #2
    Bishop84

    Bishop84 Well-Known Member

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    It's either the spark plugs or workmanship.

    You need to start by checking that every coil is plugged in, every hose is connected etc.

    Amazon has a reputation of counterfeit spark plugs, so there's a small possibility the plugs are fakes, maybe damaged etc.

    Removing one and verifying the gap won't hurt.

    Ideally, you'd put the old plugs back in, and see how it runs.
     
    JCT86, shakerhood, skidooboy and 7 others like this.
  3. Nov 15, 2024 at 7:45 PM
    #3
    TnShooter

    TnShooter The TacomaWorld Stray

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    Did you use Dielectric grease or Anti-seize when doing them? I've seen too much anti-seize cause issues.
    The same with dielectric grease.
    The grease does NOT go on the plug. It goes on the inside lip of the coil, to keep the coil from sticking to the plug .
    Dielectric grease prohibits the flow of electricity. It does NOT help it it. It "stops it".
     
    CrazyCrewChief and john003[OP] like this.
  4. Nov 15, 2024 at 7:53 PM
    #4
    DavesSR5

    DavesSR5 Well-Known Member

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    Hook up any good scanner and it should show you pending codes as well as history codes even with no check engine light (CEL/MIL)...

    But you probably installed the wrong spark plugs though, try installing the correct Denso FK20HBR8 Iridium Long-Life Spark Plugs 3491 that was designed for it... And go to your local parts house, if you have an Advance Auto or an O'Reilly Auto, they normally have online coupons...
     
    john003[OP] likes this.
  5. Nov 16, 2024 at 5:23 AM
    #5
    Greg-tacoma

    Greg-tacoma Well-Known Member

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    I am with Dave, you likely installed the wrong plugs. There is so much information on what plugs to use. On this specific topic, spend the money and get them at the dealer. Ok I know I’ll get blasted, spend the extra $$ you have already doubled the install time.
    Good luck
     
    john003[OP] and DavesSR5 like this.
  6. Nov 16, 2024 at 6:43 AM
    #6
    InThePlains

    InThePlains Well-Known Member

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    https://www.densoautoparts.com/spark-plug-installation/

     
    john003[OP] likes this.
  7. Nov 16, 2024 at 6:46 AM
    #7
    InThePlains

    InThePlains Well-Known Member

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    Do not buy plugs from Amz, period.

    I only buy from Toyota dealers during Black Friday and other big sales, cheaper, too.
     
    MGMDesertTaco and john003[OP] like this.
  8. Nov 16, 2024 at 7:00 AM
    #8
    stoney1911

    stoney1911 Professional Idiot

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    I literally just did this last weekend with the same plugs (4705s) probably from the same vendor on Amazon. Mine are working just fine. A noticeably smoother idle and run. No issues for 15XX miles. I hand tightened, hit the crush washer and then went 1/2 a turn. I’d pull your coils and give them another 1/8 of a turn or so and make sure your coils are seated on the plugs. Check your PCV line and make sure you properly seated all your connectors.
     
  9. Nov 16, 2024 at 9:16 AM
    #9
    t0p_d0g

    t0p_d0g 私はタコマが大好きです

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    What could be my issue here?”

    I agree with @Bishop84 he gave you the answer to your question.
     
    Chew, BillF1564 and Clearwater Bill like this.
  10. Nov 16, 2024 at 9:50 AM
    #10
    MGMDesertTaco

    MGMDesertTaco Come on, live a little...

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    90919-01263 or FK20HBR8

    Don't buy them from Amazon, buy from a dealer.
     
  11. Nov 16, 2024 at 11:57 AM
    #11
    kahanabob

    kahanabob Well-Known Member

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    This is why this 79 year old fart would not attempt to change my plugs myself.

    it's not my old 1990 Dakota.
     
  12. Nov 16, 2024 at 12:09 PM
    #12
    canuck guy

    canuck guy Well-Known Member

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    I understand trying to be budget conscious. But after a vehicle has served you for 75K/6 years, it deserves to go to a good shop/tech for new plugs. At the very least I would buy them from a dealer.
     
    FastEddy59 likes this.
  13. Nov 16, 2024 at 12:23 PM
    #13
    fxntime

    fxntime Well-Known Member

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    Make sure all the coils are plugged in and no wires were broken. Measure the length of the plug against an old one on both the ceramic side and threaded side.
     
  14. Nov 16, 2024 at 5:23 PM
    #14
    canuck guy

    canuck guy Well-Known Member

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    when I was a teen I did a "tune up" on my dad's car
    did not replace plug wires in correct order
    just a thought
     
  15. Nov 16, 2024 at 5:23 PM
    #15
    john003

    john003 [OP] Member

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    Update: I just picked up the 3491s from Advanced Auto Parts and also a gap gauge.

    I checked the gap on all my old plugs and they all read up to .027 but the manual says the gap should be at .032. And the 3491s I picked up are also reading at .027 Should I try installing them like this? Even the manual says to not gap iridium plugs. I figure if my old plugs and the new ones I got are the same sizes then it should fix the problem?
     
    Bishop84 likes this.
  16. Nov 16, 2024 at 5:27 PM
    #16
    BLtheP

    BLtheP Constantly Tinkering Member

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    Can’t offer much advice on this one, when I did my plugs and had a misfire after, it was because I forgot to plug in cylinder 3. Had a CEL and it ran real bad. Plugged that in and good to go.
     
    CrashZone likes this.
  17. Nov 16, 2024 at 5:29 PM
    #17
    RichochetRabbit

    RichochetRabbit Bing Bing Bing

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    The plugs for Tacomas come gapped. And you heard correctly that re-gapping iridium plugs can damage them. If you bought quality plugs this round, then install them and pay a little more attention this round (no insult intended ... just seems a good plan) to all of the details (coils back on correctly, tubs re-attached ,etc).
     
  18. Nov 16, 2024 at 5:36 PM
    #18
    hemlockz

    hemlockz Well-Known Member

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    One of the plugs could be wet with gas because it’s not firing… check that coil or cable
     
  19. Nov 16, 2024 at 5:38 PM
    #19
    t0p_d0g

    t0p_d0g 私はタコマが大好きです

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    OP, good luck this time I think you are headed in the right direction.
     
  20. Nov 16, 2024 at 5:45 PM
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    InThePlains

    InThePlains Well-Known Member

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