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Thread: Rough idle!

  1. #1

    Default Rough idle!

    Hey guys and gals,

    I recently purchased a 2008 Silverado LT 5.3L V8 with 52,000km. After getting comfortable with the ride, I noticed a rough idle, in gear, while stopped. The rpms fluctuate between 400 and 750, it never stalls but I get a bogged out feel. During the fluctuation, the oil pressure drops slightly, lights dim/flicker, and, annoying vibration.

    Plugs are original, runs in 87 octane.

    Could anybody lead me in a certain direction as to what could be the cause? any feedback is appreciated!
    ​Stay Classy, Wear a Bowtie!

  2. #2
    Sr. Engineer
    Join Date
    Oct 2010
    Indianapolis, In


    Try injector cleaner and then a plug change if that does not help. I have had good results with Lucas products and I it did more good than the Sea Foam treatment did.
    2000 GMC YUKON SLT, 5.3L tow pkg, G80 rear/w 3.73 gear

  3. #3


    I would have the alternator checked out. I was having a similar issue with my 03 and it turned out to be the alternator and battery.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

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