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Has anyone done the knock sensors on the 4.0L?

Discussion in '2nd Gen. Tacomas (2005-2015)' started by Thatgreentaco, Jul 6, 2020.

  1. Jul 6, 2020 at 9:01 PM
    #1
    Thatgreentaco

    Thatgreentaco [OP] New Member

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    Girlfriend’s 4Runner with the 4.0 has thrown the traction control light and check engine light, when I ran the code it was indicating the knock sensor was faulty. My jaw dropped when I saw the 20 hour estimate for doing the sensors by the book, but there was mention of people replacing the sensors and harness without having to take the heads off , by instead cutting the bracket that holds the coolant pipes that are obstructing the sensors from being easily removed. If anyone has done this, seen any videos or threads with this or knows a guy who has I would love all the information possible. Thank you
     
  2. Jul 6, 2020 at 9:24 PM
    #2
    Muddinfun

    Muddinfun Well-Known Member

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  3. Jul 6, 2020 at 9:26 PM
    #3
    Bishop84

    Bishop84 Well-Known Member

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    Very hard, I can do them quickly, but I have years of experience and many 12mm wrenches with various angles.

    It's almost always the subharness.
     
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  4. Jul 6, 2020 at 9:42 PM
    #4
    TacoTuesday1

    TacoTuesday1 Well-Known Member

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    Never heard of knock sensors needing replacement. I feel like a misfire interpreted by them would result in a misfire code, not a knock sensor code

    and that if there was a knock sensor code, depending on what it says, may indicate faulty wiring leading to them

    I wonder if a torch helps for that
    to heat up a wrench until it glows hot red and then bend it into a certain shape in a vice
    a cheap extra wrench maybe
     
  5. Jul 6, 2020 at 9:45 PM
    #5
    jandrews

    jandrews Carolina Alliance Southwest Region Ambassador

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    Mice got mine 6 days before I needed the truck to tow a trailer on a cross country move. Luckily I have a good mechanic for jobs I can't/won't tackle myself. He managed it in 5 hours, some $800 at the end of the job, using a bit of a hack for access which I believe was what you mentioned with the bracket cut/replacement. Apparently the damn things are down in between the cylinders in the block and the typical access involves pulling the head. Whoever at Toyota thought a goddam sensor replacement having a 20hr book time was ok should be drug out back and shot.
     
  6. Jul 6, 2020 at 9:55 PM
    #6
    Muddinfun

    Muddinfun Well-Known Member

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    I’ve cut, bent, and welded lots of wrenches and sockets over the years. I’ve made box end wrenches with about a 1” offset. I made a 1/2” really deep socket for adjusting E brake cables. About 6” long. Sometimes you just can’t get where you need to be with conventional tools.
     
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  7. Jul 6, 2020 at 10:00 PM
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    12TRDTacoma

    12TRDTacoma Powered by Ford, GM, VW, and Mercedes

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    It's true. A good mechanic has custom tools in his arsenal as well.
     
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  8. Jul 6, 2020 at 10:00 PM
    #8
    Muddinfun

    Muddinfun Well-Known Member

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    Then there’s this rocket scientist.

    82DD43E0-EB4D-4B73-BF4D-F93477ED051F.jpg
     
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  9. Jul 6, 2020 at 10:02 PM
    #9
    Amo-cat3

    Amo-cat3 Wizard Sleeve Master

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    Hey I'm one who cut the bracket holding the coolant pipes together to remove. I reinstalled without reconnecting the cut metal tab bracket and its been about 3 years now and no leaks. I was on another thread I'll try to find it, had some good info in it. I replaced both knock sensors and harness since i was so far into it. I used my M12 sawzall with short hacksaw blade and took my time cutting the tab that holds the two pipes together. It's aluminum but doesn't cut as easily as I thought it would.

    Here it is:
    https://www.tacomaworld.com/threads...p0333-diy-knock-sensor-harness-repair.547066/
     
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  10. Jul 7, 2020 at 4:22 AM
    #10
    Larzzzz

    Larzzzz Grande' Ricardo

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    I think that one flunked. Who TF decided that was a good place for a starter...? Especially with cars that shut off at lights, starters aren't going to last as long with the workout their getting.

    What motor is that out of? So I know to steer ppl away from it....
     
  11. Jul 7, 2020 at 4:28 AM
    #11
    SR-71A

    SR-71A Define "Well-Known Member"

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    That was my first thought too when I heard of the start stop function a handful of years back..
     
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  12. Jul 7, 2020 at 5:49 AM
    #12
    caffeinated_medic

    caffeinated_medic Well-Known Member

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    I just had both mine replaced. Turns out I had a head gasket leak, and the coolant was building up on the sensor.
    My mechanic definitely did the breakdown in about 3-4 hours.

    4F9A7ED7-A88B-4611-98FE-3EE0284E12FE.jpg

    So, two head gaskets, two knock sensors, one air manifold gasket, and a hydraulic tensioner later....
    Ramen noodles with a sriracha based sauce, follow me for more recipes.
     
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  13. Jul 7, 2020 at 7:10 AM
    #13
    Muddinfun

    Muddinfun Well-Known Member

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    Cadillac did it. I’m not sure if there’s other engines like that.
     
  14. Jul 7, 2020 at 7:22 AM
    #14
    hx989

    hx989 Superunknown Member

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    Toyota put the starter in the same spot on the 4.7L V8 and possibly others
     
  15. Jan 2, 2021 at 1:26 PM
    #15
    Thatgreentaco

    Thatgreentaco [OP] New Member

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    Forgot to update, but I did the knock sensor replacement with the help of this awesome video https://www.youtube.com/watch?v=pRwMXzAH19w Was fairly straight forward, only thing I recommend is to order replacement O rings for the coolant pipe, the old ones leaked when I put it all back together.
     
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  16. May 25, 2021 at 1:52 PM
    #16
    Rexfordian13

    Rexfordian13 Well-Known Member

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    Ugh...this doesn’t sound like a fun project.004FE0A9-6150-4DE2-9532-ABFFA3BC959C.jpg
     
  17. May 25, 2021 at 8:02 PM
    #17
    Taco'09

    Taco'09 Well-Known Member

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    We had an explosion of mice around here a few years ago and quite a few knock sensor wiring issues. Yum, yum that soy wire insulation + warm place to hang out on a cold night.......
    But I digress. Yes it can be done without removing the heads. Since I never ever wanted to go back in there again I stuffed that area of the 'V' under the pipe with bronze wool. Mice will not go near it. Not a problem with shorts occurring if you just keep it away a little, besides the connectors are not open.
     
  18. May 26, 2021 at 5:53 AM
    #18
    ARB1977

    ARB1977 It’s a beaut Clark

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    Not knock sensor related but a squirrel decided to chew through my abs harness. Turned that one over to insurance. 500 deductible...cost 5300 to replace, lol.
     
  19. Jun 15, 2021 at 7:33 PM
    #19
    Rexfordian13

    Rexfordian13 Well-Known Member

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    My local shop got further into the diagnostic process than I expected, offered a couple options and ended up just replacing the harness…which I appreciate greatly. I did not want to loose a summer weekend tearing into this project.
     

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