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  1. #1

    Default Detonation. . .why now?

    I have a 2007 Silverado Crew Cab, 2WD 5.3L with 45000 miles. Since new, it has not had an issue running 87 octane gas, but lately it has been pinging under moderate - full throttle. I tried higher octane gas, and though it pings less, it is still there. This truck has never worked hard a day in its life. I have thought about replacing the spark plugs, but I have had other vehicles run much further before needing replacement and doubt that this could be the problem. Could I have a bad knock sensor? If so, would the check engine light come on? I do not wish to continue spending the extra money on 89+ octane gas.

  2. #2
    murdog94's Avatar
    Join Date
    Feb 2008
    Cloquet, Minnesota, United States
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    It sounds like you have the typical 5.3L carbon build up problem. i would try a really good seafoam treatment. and then go from there because the 5.3L had a habit of building up carbon in the combustion area that would cause detonation... keep us posted as well.


    1997 Chevy S-10 Blazer 4X4 with 330K miles and counting (Hunting rig).

    2009 Saturn Aura XE (wifes car)

    2011 F-150 Crew 4X4

    "Hold it to the floor till you see God.... Then Brake!!!!"

  3. #3


    Yep a little bit of carbon build-up goes a long way.
    Try a SeaFoam treatment as previously recommended.

  4. #4
    Sr. Apprentice
    Join Date
    Nov 2010
    Ann Arbor, MI
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    Good idea on the Seafoam, but I would also clean the MAF and throttle body. I had the same issue with my Suburban along with an occasional check engine light when under hard acceleration. Cleaned both and it is running like a dream.

    Good luck!

    2003 Suburban
    1968 Camaro 454

  5. #5


    Yep, Seafoam, clean throttlebody and MAF.

    2005 Chevy Silverado Z71 Crew Cab
    6" Skyjacker lift w/Edlebrock dual front remote resoviour shocks, single rear remote. Rancho skid-plate.
    17" x 9" M/T Classic Lock Wheels, 35" BFG A/T or M/T tires
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    Banks CAI intake, ported throttlebody, JBA coated headers, over-sized Magnaflow cats, Magnaflow cat back exhaust, Diablo tuned
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    One black Lab in rear seat.

  6. #6


    All good advice here...

    Don't forget to do a fuel pressure test. Low fuel pressure will cause detonation, which causes damaged rod bearings, which causes...
    When you hear hoofbeats, look for horses not zebras.

  7. #7


    Sounds like good advice to mem does the truck diesel when you shut it down?

  8. #8


    It's not going to diesel, the fuel pump and injectors are off.

  9. #9


    That's a good point.

  10. #10


    Well, after adding a can of Seafoam during my last fill up, the detonation is much less than it was. I will try another can with the next fill up and let you know if it finally goes away. Thanks for all of the ideas.

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