1. We are working on the forum's attachment system. Attachments and avatars will be intermittently affected over the next 24 hours.
    Dismiss Notice

Random Flashing CEL

Discussion in 'Vortec 4.2L I-6' started by littleblazer, Jan 2, 2017.

  1. littleblazer

    littleblazer Gold Supporter

    Messages:
    6,678
    Likes Received:
    3,235
    Hey guys, as a lot of you know I have been chasing down a random stall out issue for the last 2 years or so on the truck and it has gotten progressively worse as time has gone on. See that thread here. I have tested everything I can to no avail and checked what I can with the data logging on the tech II still with no hard evidence of anything, well... crapping out. It still only stalls in the summer when it is hot out but it used to only be once or twice a year in the beginning. It then went to once a month then to almost a daily occurrence at some points and I couldn't catch it. Whenever I had the tool logging it behaved. Even when I could duplicate the issue 3 times in a row when plugging in the tech 2 it would behave. It was at the point where I could start the truck walk in a backyard and come back out to it not running. It would just die idling. The easiest way to get it to do it is a decently hard acceleration on a hot day to around 55 followed by a coast to a stoplight and then sitting there at an idle for a few minutes. That is the most consistent duplication I can create. And it always happens as the light turns green lol. I am restating a lot of what is in that other thread but some new issues have arisen.

    Now on the highway I am starting to get a random flash of the CEL, usually coasting onto an on (or off) ramp and just bliping the throttle (idle to maybe 1000 rpms). I am going to go on a limb and say it is related but no one wants to do a ride along so I can data log unless it's their vehicle. It's kind of hard to run the tech II and drive at the same time on the highway... Well okay, I just don't want a ticket or anything, I can do it but it makes me uncomfortable if you get what I mean. When the cel comes on, or well flashes, you feel the truck lose power for like a split second, almost like the motor is killed for a second, everything goes stalled mode for a flash of a light. I think it's getting worse as today it happened a few times in town and I am just worried it's going to start dying on me on the highway. If anyone has some tests I can look into that are easy to run myself, they would be greatly appreciated. Thanks in advance.
     
    Redbeard likes this.
  2. Mooseman

    Mooseman Moderator

    Messages:
    10,031
    Likes Received:
    4,617
    A flashing CEL usually means a misfire. You should check your misfire counts after getting the CEL.
     
    Mounce likes this.
  3. Mounce

    Mounce Silver Supporter

    Messages:
    12,348
    Likes Received:
    7,889
    Plug replacement history?
     
  4. littleblazer

    littleblazer Gold Supporter

    Messages:
    6,678
    Likes Received:
    3,235
    Well it just flashes once. Not like a misfire. Plugs done at 115k we're at 170 now. 1 coil pack failed so I replaced it. The flash lasts less than the blink of the directional and it only does it once...
     
  5. Blckshdw

    Blckshdw Moderator

    Messages:
    7,685
    Likes Received:
    6,447
    This topic came up a few years ago, as a number of us, myself included, had noticed this happen at a seemingly random rate.

    In my cases when I've noticed it, it's when I let off the gas pedal and coast. Usually in city traffic, approaching a red light. Would only see it if I was already looking at the cluster, or at the pavement right in front of the EXT. Quick little blip, easy to miss, and no pending codes on the SGII or Torque. No change in the truck's behavior other than that. Been happening for the 7 years I've been driving it.
     
    smt 59 and littleblazer like this.
  6. littleblazer

    littleblazer Gold Supporter

    Messages:
    6,678
    Likes Received:
    3,235
    That's primarily when I notice it as well.
     
  7. smt 59

    smt 59 Well-Known Member

    Messages:
    3,354
    Likes Received:
    1,118
    Had this since new, means nothing and I ignore it, same as the occasional battery gauge drop and lights randomly dimming like a surge or something. Chase it as much as you can but you will never find it.
     
    djthumper likes this.
  8. littleblazer

    littleblazer Gold Supporter

    Messages:
    6,678
    Likes Received:
    3,235
    Well the diming lights and surge is the funky pcm voltage regulation iirc. But that still doesn't explain the drop in power when it happens now that I think about it. When it does it you feel the truck kind of jerk.
     
  9. Trkdrvremt

    Trkdrvremt Gold Supporter

    Messages:
    347
    Likes Received:
    345
    Do you have a tech II? If so I could come down and drive you around.... Let me know when you want to set it up...
     
  10. littleblazer

    littleblazer Gold Supporter

    Messages:
    6,678
    Likes Received:
    3,235
    Thanks for the offer. :tiphat: But I wouldn't make you do that. With my luck it'll behave again the second the tool hits it. I'm at the point that the blinking cel is not the issue and something else is still going on anyway so I guess I'll wait until it gets warmer and I know it'll act up and then start doing ride alongs then. You're more then welcome to come down when it's only below freezing inside the truck. :rolleyes:
     
  11. smt 59

    smt 59 Well-Known Member

    Messages:
    3,354
    Likes Received:
    1,118
    There is no difference in performance at all when it happens, no jerk or stall feeling at all just keeps on trucking.
     

Share This Page