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Thread: 05 GTO Intermittant Misfire hesetation

  1. #1
    Registered Newbie

    Join Date
    Aug 2016

    05 GTO Intermittant Misfire hesetation

    Hey folks newb here on the forum and I'd thought I'd spitball a rather annoying issue to see if any of you folks have come across this.

    2005 GTO LS2 Stock engine 127k on the block.

    Cold running engine performs normally stable Idle no hesitation.

    after 15 minutes or so, the vehicle goes into a state where it will accelerate normally from dead stop but if the vehicle has the brake pressed momentarily or RPMs drop below 1.5k, any acceleration will have hesitation and / or misfiring till i get her back above the 2k zone. now it is not consistent, so it doesn't do it all the time in this state, sunny warm days are the worst. overcast days, problem hardly shows it's self.

    I've taken it to a GM dealership and complained about the issue and they were not able to track it, and it's not throwing Check engine code.

    I can't seem to determine if it's spark or air/fuel, let alone if it's bad timing read..

    anyone have something like this happen to them?


  2. #2
    Registered Newbie pinkblob66's Avatar

    Join Date
    Aug 2016
    Tampa, FL
    I was having a similar issue and actually just posted about it, but my issue ended up being an O2 sensor. I was having codes, but they were not constant. They would appear and then go away after a couple turns of the key. It seemed to happen after the vehicle warmed up and during the day, but not so much at night. Found out by looking at the plugs and noticing bank 1 was fried compared to the other side. Changed out the O2 on the driver side and I was good to go.

    I'm not saying that changing the sensors is the way to go, but definitely check your sparklers for inconsistencies. Just my $0.02

    I also wouldn't rule out a vacuum leak.

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