bad engine knock! PLEASE HELP!!!

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by yeevveey211, Mar 16, 2013.

  1. geo1

    geo1 Member 1 Year 100 Posts

    j cat,i enjoy reading youre input,to the po300,have you seen one go away?on own,my few expierences always needed a relearn,even after problems fixed,input helpful thanks
     
  2. j cat

    j cat Rockstar 4 Years 1000 Posts

    yes on my 2000 I had this glitch occur 2 X over the 13 years. In the oem shop manual it actually explains how this can occur with no failures.

    If the engine has a sudden surge in torque it is possible that the timing sensors get out of position for a milli sec and then the p0300 will come on. then the check engine light will stay on for many start cycles before it resets. I twice had to manually reset this and no issues so far.

    I never used the relearn . some have had to use the relearn when replacing the timing sensors but not all.

    It seems that most times this is due to low fuel pressures/low fuel volume. weak pump ,regulator, or not replacing the fuel filters if installed.
     
  3. yeevveey211

    yeevveey211 New Member



    does just the engine light show up for those start cycles or does still misfire?.

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    i disconnected my battery and am going to battery test Tom . simple first. checked my plugs they are all fine Dosent look like they need to be replaced . I Have had no Time to work on her . I also am going to spark test all coil packs to see if hats the problem. I don't have a fuel pressure tester I wish I did to check the injectors .
     
  4. j cat

    j cat Rockstar 4 Years 1000 Posts

    auto zone / advance auto should have the pressure gages.
     
  5. geo1

    geo1 Member 1 Year 100 Posts

    this is why i am here,my last po300 was solved with a relearn,but not before changing front knock sensor and pig tail harness,02 silverado 6.0 liter,constantly learning here!
     
  6. j cat

    j cat Rockstar 4 Years 1000 Posts

    with the KS having a bad connection this would cause the timing to jump creating the 300 code. also this most always will produce the KS code .

    washing the engine usually causes the KS issues. the upper intake was not properly sealed at the factory build. TSB states to seal the front and leave the rear open .
     
  7. yeevveey211

    yeevveey211 New Member

    u know I was thinking about that because up here in photo we only had once very nice day and I washed my truck before work and now it's snow gain son of a b**** I washed it before work and this happens the morning after

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    so your saying take the intake manifold off and check the two knock sensors connections?
     
  8. j cat

    j cat Rockstar 4 Years 1000 Posts

    look between the upper and lower intake manifolds at the front of the engine . is the space sealed or open . if open a very good chance this is a problem.

    I had rodents chew on the foam GM used causing this to be open slightly but I caught it before any damage was done.

    I used a silicone based gasket sealer with a foam material . worked the pre cut/shaped foam first then applied sealer to foam and then installed for a very water proof flex gasket . then after the sealer set applied more sealer to the face of the gasket material . so far it is still perfect.

    rodents dont like this stuff around here anyway.
     
  9. yeevveey211

    yeevveey211 New Member


    had checked about half hour ago . no open spaces or gaps.
    but since it's the only nice day for a week or so here I took advantage of it and checked a couple of things for my truck.
    1. battery is good and has good cranking amps and at a solid state
    2.hooked up computer it cleared the p300 code
    3. still knocking . but have good spark through all cylinders
    but I did find a little glitch here when I washed my truck the day before this happneed there is a leak through the weather stripping above the firewall. I took a couple pictures for ya guys

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    sorry lts not turned. but you can see the bent weather stripping and I could see where the water when down on top if the motor.
     

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  10. geo1

    geo1 Member 1 Year 100 Posts

    thanks for tsb info,i left rear foam in,will remove asap,back to po300 on yees v rod,any symptoms?i had none,took a month before k.s. code came up

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    good question,say the vehicle was parked down hill,would water wick thru from rear onto valley?
     

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