living that false knock life.

Discussion in 'Forced Induction - 5.0L V8 Engine' started by Tugger50H, Jun 1, 2018.

  1. Tugger50H

    Tugger50H Well-Known Member

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    So much has changed on the car. Recently had a converter installed, replaced exhaust (old exhaust had a broken baffle), 18 intake manifold. Tuning the intake noticed I was getting positive knock and i'm running out of ideas.

    I have found a handful of things i thought would resolve the issue and while I feel like I have made progress in getting it to knock less the I have gone from +4 spikes to +8 spikes.

    Any idea or suggestions greatly appreciated.

    datalog12.jpg
     
  2. OP
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    Tugger50H

    Tugger50H Well-Known Member

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    Well discovered a transmission bolt on the passenger side that was forgotten. Not sure how long those are but it was sticking about roughly two inches and rattled pretty good when I tapped on it. I'll keep searching and giving everything a once over but think something like could cause my knock?
     
  3. Jimmy G

    Jimmy G Hangin' about, waitin'..

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    Yep, absolutely.
     
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    Tugger50H

    Tugger50H Well-Known Member

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    Well besides putting the stock exhaust on I think I have touched every bolt twice now. Outside of that it's either real knock or the tune. I'll see what she does tomorrow.
     
  5. 09jsw

    09jsw Well-Known Member

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    Could be bad gas. Throw some race gas in or oct booster
     
  6. wildcatgoal

    wildcatgoal @sirboom_photography

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    The flex joint on the passenger side OEM exhaust "header" can cause false knock. If you have SP/SW headers, your header pipes could be vibrating on each other. Known some instances where they had to be spread a wee gnat's ball hair to stop that.
     
  7. Roh92cp

    Roh92cp Well-Known Member

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    I get some positive knock when shifting hard at WOT 3 to 4 usually see like 3.5 positive right after a shift which smooths out after a bit. I wonder if the motor shifts or moves hard a the shift and hits something causing that.
     
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    Tugger50H

    Tugger50H Well-Known Member

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    Well I have managed to make it worse. I didn't do much of a pull but at WOT it was adding timing the whole way. After the pull cruising 60mph, 20% throttle it saw a +8 that was more than just a single spike. Thinking at this point it could maybe be the exhaust but I have been over dozen times only thing I could do is put on the stock axle back. Only other guess is it's the tune or I have a real issue.

    I'll going to try the stock exhaust even though I feel like I'm wasting my time then it's. Compression and leak down test.


    Car is on pump e85. Last three fill ups have tested 85-90 on my hydrometer.
     
  9. kcc0521

    kcc0521 Well-Known Member

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    Where did you buy the hydrometer and how much are they? I had false knock after my 2018 intake install on e85 as well. If you have a auto dipstick tube please make sure it is not hitting the head. Also check exhaust tips to valance. My car like to create false knock when making pulls on the street with traction control on.
     
  10. isedawishy

    isedawishy GTPPTT6REIGHTY

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    Bang around on the exhaust! I agree with checking the exhaust tips. That was one of the culprits for me.
     
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    Tugger50H

    Tugger50H Well-Known Member

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    Put the stock exhaust on and didn't seem to make huge difference just cruising around. Still saw some small knock spikes but I did manage to get a clean solid WOT pull for tuning.
     
  12. 205.0

    205.0 Well-Known Member

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    I had the exact same blower setup and could never figure it out. Went over the whole car over 10 times throughout 3 months. Ended up selling the kit and no knock since.
     
  13. sigintel

    sigintel Well-Known Member

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    You try swapping back drive shaft?
     
  14. venumous

    venumous Well-Known Member

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    Knock is fun times. Love it.
     
  15. Joe 5.0

    Joe 5.0 Well-Known Member

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    Good ol' false knock; it's driving me nuts!

    Check your cold air intake tube and make sure it's not pressed up against the hood. When I had the GT350 TB installed, it was difficult to close the hood because of the tube, and I think that was causing most of my knock. Also, check bolts underneath the hood was well (IM bolts, fuel rail, etc.).

    I have about 1 degree of knocking during WOT pulls and the shit is driving me nuts.
     
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