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Need help with multiple cylinder misfires.

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by Jhein, Jun 27, 2012.

  1. Jhein

    Jhein New Member

    I can't believe with all of the issues my truck has given me in the last couple of years, I haven't found all of you yet.

    I have a '99 V6 Silverado (Manual) with roughly 200k miles on it. Starting about a year and a half ago, I've had numerous problems with cylinder misfires. It happens whenever it wants. The first time it happened, I replaced the plugs and the wires to no avail. Finally was advised to change the distributor cap, and I did so. That seemed to take care of the problem. (Thanks chevy, by the way, for putting the Distributor cap in such an easy to reach place:grrrrrr:).

    About three months later, it did the same thing. Thinking that, with the new cap, it couldn't possibly be the issue, I took it in. Yet it was. The same thing. A hole burned right through to two terminals which I guess crossed the power. Ok, so problem fixed. So now about six months ago, same problem. I thought, ok, 65 dollar fix or something from the mechanic, good deal. Take it in. They tell me thats not it. The replace the distributor, because, as they told me, that's it.

    Except it wasn't. They called and said it was worse. It was the Spider assembly. Something I'd never heard of, and it sounded expensive. And it was. The whole bill was 800 bucks when all was said and done (even with me supplying the spider assembly off an extra engine I have for the truck). The night I drove it home, I had the problem again. Straight from the mechanic, it didn't even make it home. The truck will idle fine (or fine ish, If I rev it, I almost think I can hear (or not hear) a missing cylinder). But it's totally undrivable. I fixed it then with some STP fuel cleaner. And that was that.

    So over the last week, I've noticed a loss of power. It wasn't lugging but I could feel just a little jumpiness, like the power was coming and going. Now it's all out, all over again. It must take me 30 seconds to get up to 40 mph. I added some better gas and HEET, to no avail.

    Again, to describe it, it idles fine I guess. It doesn't backfire when I rev it at idle. But when I start from a stop, it's lurching forward, the gas is coming and going. The sound says I'm definitely misfiring.

    I really can't afford another few hundred dollars in repairs, so I need to be a bit more effecient in my replacements. I haven't come here yet having tried anything but fuel treatment, so I want to know where I should start. Could there be a problem with the newer cap again? Does it sound more fuel related? It threw out codes, which I'm going to check tomorrow, but I would bet my life savings it will just be random cylinder misfires.


    I'm 22, not mechanically oriented at all (although I can do the work, I just don't know where to start). Any advice would be appreciated. Maybe people who have had the problem I've had. I'd really appreciate it, everyone.
    Last edited: Jun 27, 2012
  2. Chris Miller

    Chris Miller Rockstar 100 Posts

    See what the codes say. The fact that a couple of distributor terminals melted might indicate some issues with the ignition control module.
  3. Jhein

    Jhein New Member

    Well really what it did was tear through the material between the terminals, and the electricity was sort of fighting itself.

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