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Help: Engine Vibrations

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  • #1

    Help: Engine Vibrations

    Help! Engine Vibrations >>>
    Are engine vibrations stuff to worry about?
    is it bad? Will it affect my performance?

    I first noticed it
    a couple of weeks ago when I was revving it up for some
    friends. One of them told me that my car was shaking
    (back and forth sideways) I was reving it in neutral with
    the cut out open. Also recently (a couple of weeks ago
    I started hearing this slight rattle coming from behind the
    instrument panel) (not very loud rattle)

    Note: The car didnt make such vibrations months ago,
    I have'nt gotten in any accidents ever, I baby the
    car most of the time and dont race to often, I dont see how
    any big harm could have come to it.

    it dyno'd 300rwhp just 8 months ago (completely stock
    except k&N airfilter.

    1998 z28, m6.
    Tags: None
  • #2
    I dont know how experienced you are with cars, so this could be a dumb question. Are you sure that your firing on all eight; a miss can cause quite a vibration and can come on quite suddenly.
    96 WS6 Formula: Ram Air, 383 Stroker, Ported LT4 Heads and Manifold, 1.6 Crane Rollers, 58MM T.B., AS&M Headers, Borla Exhaust, Meziere Elec. H2O Pump, Canton Deep Sump Oil Pan, 100 HP OF TNT N2O!! , T56 Conversion w/ Pro 5.0 shifter, SPEC Stage 3 Clutch, Hotchkiss Subframe Conn., Lakewood Adj. Panhard Bar, Spohn Adj. LCA's, BMR Adj. T.A., Custom 12 bolt w/ 3:73's, Moser Axles, Eaton Posi, Moser Girdle
    11.6 @ 123mph (1.6 60' - getting there )

    Comment

    • #3
      re

      Im not sure if all eight are firing or not? I dont have much
      mechanical experience with cars. The vibration is not that
      big, I didnt even notice it while I was driving the car untill
      the mechanic pointed it out to me. He said it could potentially
      be a performance problem like a misfire but he wasnt sure
      without doing a diagnostic.

      Comment

      • #4
        Is it lacking power? If so, it could be misfiring. Judging whether or not it is a misfire or another vibration usually comes with experience, but the best thing to do is check and see if all eight plugs are firing. If your into doing it yourself that is. You can buy an inline spark checker at a good auto parts store or auto tool supply place. This simply plugs in line between the plug and the wire and lights up if that cylinder is firing. Otherwise you would have to pull all the plugs, which is a headache. If you find it is an ignition misifre then we can go from there with the diagnosis. If all of the plugs are firing, it could still be a misfire due to lack of fuel (bad injector or wiring) or compression (bad rings, valve etc). These causes are much less common though, especially since its so new. If its not a cylinder misfiring there are still other avenues to explore such as engine balance or maybe a bad MAF or TPS etc. making it run rough.
        96 WS6 Formula: Ram Air, 383 Stroker, Ported LT4 Heads and Manifold, 1.6 Crane Rollers, 58MM T.B., AS&M Headers, Borla Exhaust, Meziere Elec. H2O Pump, Canton Deep Sump Oil Pan, 100 HP OF TNT N2O!! , T56 Conversion w/ Pro 5.0 shifter, SPEC Stage 3 Clutch, Hotchkiss Subframe Conn., Lakewood Adj. Panhard Bar, Spohn Adj. LCA's, BMR Adj. T.A., Custom 12 bolt w/ 3:73's, Moser Axles, Eaton Posi, Moser Girdle
        11.6 @ 123mph (1.6 60' - getting there )

        Comment

        • #5
          re

          Thanks for your response. I can't really tell whether
          there's something wrong from just the feel but Im supposed
          to be going up to the track on the 6th anyway so I guess I'll
          find out. If there's any more indication of a problem I'll prolly
          have to get it looked at perhaps at the dealer.

          Comment

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