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Thread: Engine Underboost DTC?

  1. #1
    Lifetime Member LBZoom's Avatar
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    Default Engine Underboost DTC?

    Hey guys,

    I've got a 2006 LBZ engine, and lately I've had a DTC come up for an engine underboost code, and I'm thinking there's no way it can be underboosted....I've turned the turbo up a pretty fair amount and i'm not even cranking enough fuel to blow smoke when it kicks down yet

    Also, looking at the tables for desired boost w/EGR off, at 800 RPM's the desired boost levels range from about 14-17 lbs of boost in my particular tune depending on altitude, and according to my log file the truck idles (700RPM) at about 15lbs of boost....my gauge shows the truck idling between 2-4lbs of boost...which one is right? What kind of boost pressures are some of you guys reading on your gauges at idle?

    Here is my log file...starts with idle, then a couple revs, and then take-off
    Attached Files Attached Files

  2. #2
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    You have to deduct baro pressure to get boost pressure. At sea level it's 14.7 lbs, so if you were reading 20lbs at sea level, it's actually like 5.3 lbs of boost.

  3. #3
    Lifetime Member LBZoom's Avatar
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    Ohhh...okay now I understand haha. Thanks man!

  4. #4
    Lifetime Member killerbee's Avatar
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    its a misnomer code. You get it when vane position is maxed out, and you still cannot attain desired boost. It typically codes when doing what you are doing.
    Michael, Systems Engineer 04.5 D-max LLY, Phoenix, Arizona Email
    Custom Tuning Services
    DURAMAX/CUMMINS ECM's TCM's for sale, all years, 20% wholesale discount available
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  5. #5
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    if your target vane position isnt close to what it should be for your desired boost it can throw it. also if you arnt making what you call for it can too. I swing no boost at an idel.
    Philip
    V2 from Tippin
    2010 Camaro LS3

  6. #6
    Lifetime Member LBZoom's Avatar
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    Awesome thanks for your help guys!

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