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  1. #11
    Jr. Mechanic
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    Mar 2013
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    adirondacks,n.y.
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    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. #12
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    Sep 2010
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    everett, massachusetts
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    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. #13

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    Quote Originally Posted by j cat View Post
    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.


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

    - - - Updated - - -

    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 .
    2005 chevy reg cab 2500 6.0l
    bds 7" ntbd high clearance kit
    7%tint 15% Windsheild tint

  4. #14
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    Sep 2010
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    Quote Originally Posted by yeevveey211 View Post
    does just the engine light show up for those start cycles or does still misfire?.

    - - - Updated - - -

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

  5. #15
    Jr. Mechanic
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    Mar 2013
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    adirondacks,n.y.
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    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. #16
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    Quote Originally Posted by geo1 View Post
    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!
    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. #17

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    Quote Originally Posted by j cat View Post
    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 .
    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

    - - - Updated - - -

    so your saying take the intake manifold off and check the two knock sensors connections?

  8. #18
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    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. #19

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    Quote Originally Posted by j cat View Post
    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.

    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

    - - - Updated - - -

    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.
    Attached Thumbnails Attached Thumbnails image.jpg  

  10. #20
    Jr. Mechanic
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    Mar 2013
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    adirondacks,n.y.
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    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

    - - - Updated - - -

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

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