2008 5.3 suburban misfiring cyl #6 fouled plug repeatedly , oil...

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Thread: 2008 5.3 suburban misfiring cyl #6 fouled plug repeatedly , oil...

  1. #1
    Walking
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    2008 5.3 suburban misfiring cyl #6 fouled plug repeatedly , oil...

    I am new to this forum. In advance ,I thanks all of you for all the information I already collected .it has helped me pinpoint my issues..
    So,here we go :

    2008 truck , 4x4'built in USA,engine manufactured in 2008 February,truck finished in February and shipped to africa where I ordered the truck through a gm dealer.

    It has 50k approx. it has been great till recently.
    Took it to the gm dealer after it started misfiring and the code showed up as check engine and stabilitrak.

    The put a scanner and clearly showed cyl #6 misfire.
    We took all plugs out with the gm tech . All plugs perfect but #6. It was fouled because of oil.

    We put new plugs in it...erased the codes..started the engine..ran great for 2 min.. Then again,scanner showed cyl 6 misfire.

    Took it out and oil it is !
    The tech was quick to say u need a new engine ....after sone arm twisting,we got to ..you need pistons and rings ....then I read all the forum info on oil burning and lugs fouling and called them back last week. I am in Canada and keep the truck there.

    So here are my research and questions ... I am getting killed there with techies that never and don't know zip about the common issues of 5.3 of oil and plug fouling , and valve covers with baffles, and flex fuel regulators for spraying oil to the cylinders that go bad, and all the different tbs ... They are lost and ignorant. I am forced to do all the work for them of else I am lost with the truck there. I need to pinpoint as best as I can and take the parts with me next week.

    I never did an oil consumption test but it seems not to be an issue at all..no smell, no smoking..and the is fire issue is a first for the truck. Been great so far.

    - are my rings shot on cyl 6 ?
    -are my rings sticking and need the cleaning for rings gm recommends ? If yes, then why did just that one cylinder stick and all others remain perfect ? Wouldn't make sense..
    -valve cover with baffle....PVC valve,... I understand 08 had the new style valve covers ? And even if mine had the old style, wouldn't I find oil on more than one plug that would misfire or at least show sins of oil. ...?
    -can it be from the valve or valve guide or seal ?
    -can it be frm the flex fuel where apparently,08 motors we made with a different oil spraying system for each cylinder ..and in my case,#6 sprayer is not regulated properly or defaulting therefore shooting too much oil ? In that case, I could just have the cleaner tbs for the rings gm recommended, then fix the regulator issue of the flex fuel ..
    Please , consider my motor was build in feb 08, any ideas would be greatly appreciated. I travel next week. Mechanic wants me to bring be piston,one ring set,crank bearings,and all gaskets.... I am not convinced I need new rings , I feel Otis either coming from the fuel flex system or maybe the valve cover. (but then again, why just cyl 6 if the valve cover would be at error,then a few cyl would see oil..not just cyl 6) ...
    So am I right to feel all is pointing to the flex fuel system sprayer of cyl 6 !?
    How do we check this ? What's the way to see if defective or they say we need to reroute it with a shield.. .???

    Thanks in advance .

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  3. #2
    Walking
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    Re: 2008 5.3 suburban misfiring cyl #6 fouled plug repeatedly , oil...

    fouledplugvcdesign.txtStevemaman,

    Here are 2 bulletins that describe your issue, although the 1st is for cylinders 1 and 7, and the 2nd is for AFM engines. However, a PCV issue is the same with any of these motors, so check and see what a set of 2nd design valve covers run.....just for PM if for nothing else. Good luck...

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    6.2 Liter LS9 Supercharged V8 MrCritical's Avatar
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    Re: 2008 5.3 suburban misfiring cyl #6 fouled plug repeatedly , oil...

    If you have the AFM engine, DO NOT go by the oil life monitor. 4000 miles is tops for an oil change.

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    1.8 Liter ECOTEC Mr. Myagi's Avatar
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    Re: 2008 5.3 suburban misfiring cyl #6 fouled plug repeatedly , oil...

    Needs pistons and rings all 8 cylinders. Change your oil more frequently as stated above. The
    valve cover was poorly designed causing issues, suprised its 6 though. Usually 8 is fouled out pretty bad.



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