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Thread: What Is My O2 Sensor Telling Me?

  1. #1
    Tuner tonyvette's Avatar
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    What Is My O2 Sensor Telling Me?

    Around frame 11800 in the enclosed log, my bank 1 O2 sensor goes crazy while bank 2 stays static. Can someone guess at what is happening here? Misfire? Exhaust leak? Weak coil? I swapped coils from side to side this morning, but haven't logged yet to see if the problem switched sides.
    Thanks for your help!
    Tony

    8-18 afternoon.hpl
    2012 Colorado 5.3
    Magnum 70mm turbo
    RevMax 2800 stall converter
    DevilsOwn meth

  2. #2
    Senior Tuner SultanHassanMasTuning's Avatar
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    you got some misfiring there, another indication would be a lean AFR mixture... I see that your MAP is also high (what you got going on under the hood there tony )
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  3. #3
    Tuner tonyvette's Avatar
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    Hey Sultan! Trying to get the tune on my turbo straightened out! I logged after swapping coils from side to side. Still acting strange on bank 1. My plugs are Weapon X heat range 6 gapped .035. Plug wires are MSD Super Conductor 8.5s. I thought maybe I was spraying too much meth...7# nozzle, 40/60 meth/water mix. But that would show on both banks, right? Exhaust leak maybe? I don't see any indication of a leak around exhaust manifold or O2 sensors, but my exhaust is wrapped. Maybe I need to unwrap it and look closer? Would an exhaust leak cause this?

    8-19 lunch early.hpl

    Look at frame 15450

    As always, Thanks for your help Sultan!
    2012 Colorado 5.3
    Magnum 70mm turbo
    RevMax 2800 stall converter
    DevilsOwn meth

  4. #4
    Senior Tuner SultanHassanMasTuning's Avatar
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    this is pure a misfire event happening to your Bank 1:

    Bad coils
    bad plugs
    gapping not enough try .030

    try the stock coils and see what happens. i have used stock on high hp and never had issues
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  5. #5
    Tuner tonyvette's Avatar
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    I have the stock coils on the truck. I've read the stock truck coils are plenty strong so I never upgraded.

    I guess I'll pull the Bank 1 plugs first and regap them to .030. Is there a way to log and see which plug is misfiring?

    Thanks Sultan!
    2012 Colorado 5.3
    Magnum 70mm turbo
    RevMax 2800 stall converter
    DevilsOwn meth

  6. #6
    Senior Tuner SultanHassanMasTuning's Avatar
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    yes you can see the misfire counts per cylinder in the Primary table
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  7. #7
    Tuner tonyvette's Avatar
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    Got it. I loaded the table with current misfire for each cylinder but that was difficult to follow. So I loaded history misfire tonight. Will log tomorrow and see what it shows.

    It did show some misfires when I was looking at "current" but it didn't look like it corresponded with the spikes in my O2. It was just one or two occasional misfires in different cylinders during high load boost. This shit gets confusing!!!
    2012 Colorado 5.3
    Magnum 70mm turbo
    RevMax 2800 stall converter
    DevilsOwn meth

  8. #8
    Tuner tonyvette's Avatar
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    So I logged both current and history misfire and neither seems to correspond with the spikes I see in my Bank 1 O2. Are the misfires not being detected? Spark blowout? Last log with misfire history below:

    8-21 morning.hpl
    2012 Colorado 5.3
    Magnum 70mm turbo
    RevMax 2800 stall converter
    DevilsOwn meth

  9. #9
    Tuner tonyvette's Avatar
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    Today I regapped all my plugs to .028-.030. All the plugs looked good, white insulators. clean ground strap and tip. Misfire is still bad as ever. So I have removed the exhaust pipe from Bank 1 side to check for leaks. Nothing sooty visible around welds or O2 bungs, but I'm gonna grind down and reweld everything anyway since I have it out and unwrapped. This is really baffling me!

    8-23 regap plugs.hpl

    Frames 26600-26800 show serious misfires Bank 1. This is AFTER gapping plugs to .028-.030.
    2012 Colorado 5.3
    Magnum 70mm turbo
    RevMax 2800 stall converter
    DevilsOwn meth