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Scanner shows misfires but not on individual cylinders.

Discussion in 'Chevy Trucks' started by 70monte, Jul 19, 2010.

  1. 70monte

    70monte Senior Member
    Messages: 468

    I had my Autoxray 6000 scanner hooked up to my 98 K3500, 7.4L/4L80E and noticed that it showed some misfires in the misfire count but that under misfires for the individual cylinders, they all showed 0. What could be causing this to show up like that?

    There are no trouble codes stored or SES light showing and the truck has always idled kind of rough even with a full tuneup and new distributor. The truck doesn't feel like its missing when its going down the road.

    Is this anything to be worried about? Thanks.

  2. lotec25

    lotec25 Member
    from Florida
    Messages: 47

    Never used this scanner before, so i might be going in the wrong direction. But do you have to select what vehicle/motor it has? And if so is it set correct? You could allways run by autozone/advanced and see if there's shows the same just to rule It out. How is the exhaust? are the cats clean? Kind of strange even after a tuneup it still has a ruff idle. Does the Autoxray show you full pressure?
  3. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Ignore the misfire counts. All engines misfire to a degree and many scanners allow you to monitors them. The counts visible on the scanner are only for the CURRENT drive cycle anyway and don't give you any real clues to an issue until you already have one. And when/if you do by then it will produce enough misfires (indicating a real problem) to set a hard code for it. Just like what you looked for and found none.
  4. 70monte

    70monte Senior Member
    Messages: 468

    Thanks for the info. On this scanner you select the brand(GM) and then the year. The exhaust appears to be okay and the cats look original(103,000miles on truck) The tailpipe is very clean with no black soot at all. I replaced both precat O2 sensors a few thousand miles ago.

    I will ignore the misfire counts. I did notice while monitoring the scanner that the misfire counts were going up and then all of a sudden it showed a lower number so I wasn't sure what that meant. Thanks again guys.