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Thread: MAF Signal

  1. #1
    Member Spindoctor's Avatar
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    Jun 2007
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    Default MAF Signal

    Hi all!
    Since I am new to GM format tuning (see my signature below) I have a question concerning the MAF output of this 06 LS2.
    When looking over logging files after a run the MAF raw signal (and other directly associated PID sigs) do not rise linearly with the RPM. They tend to rise and fall erratically. Is this a normal characteristic of the GM MAF? (resonant manifold sensitivity?)
    I am a BMW\Benz tech by day and any sig like this would get the MAF a trip to the dumpster.
    What I am trying to isolate on the particular engine is a constant Knock timing retard of about 2-3' from 2500 through 5500 at WOT.
    Could be our poor winter gas.
    Car runs great 330rwhp and 351rwtq. @12.25:1 afr. I think it could be better
    but not with KR happening.
    And whats up with the 82% max thrtl. Is that GM for WOT or do I have an issue?

    Also- Customer is complaining of the delay during paddle shifting. I agree it is SLOOW. Ferrari's will shift before you can lift off the paddle.
    He is a very competitive driver locally and this is his biggest issue.
    Is there anything I can adjust to make this shift faster\firmer?

    I promise to return info to the forum once I have learned a thing or two or five!
    Thanks in advance- The Spindoctor (Tim H)
    Back ground-Mustang AWD500 Dyno- Over 500 tunes on systems including: Autronic, MoTec, AEM,COBB,Haltec, Electromotive,Greddy, Microtech (to name just a few)and now EFI Live!

  2. #2
    Lifetime Member hymey's Avatar
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    Default

    Hi Spin,

    The knock sensors are very sensitive in these engines and I wouldn't rely on them for accurate data. I have heard these engines knock and the knock sensors didn't pick it up but on the other hand it has picked up false knock on numerous occasions. Turn KR off and run the car on the dyno. Listen for knock adjust timing accordingly and then enable the KR function and keep a close eye on it. You can adjust the KR settings.

    Cheers

    Joel

  3. #3
    Lifetime Member GMPX's Avatar
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    Quote Originally Posted by Spindoctor
    What I am trying to isolate on the particular engine is a constant Knock timing retard of about 2-3' from 2500 through 5500 at WOT.
    Could be our poor winter gas.
    What sort of timing is it trying to get at WOT?, pull 5 degrees out and see if the knock goes away, look at the tailpipe, it is puffing black smoke?

    Quote Originally Posted by Spindoctor
    And whats up with the 82% max thrtl. Is that GM for WOT or do I have an issue?.
    It's a GM thing.

    Quote Originally Posted by Spindoctor
    Also- Customer is complaining of the delay during paddle shifting. I agree it is SLOOW. Ferrari's will shift before you can lift off the paddle.
    Ferraris cost more that's why
    Paddle delay is an on-going issue, but the box can be made to shift a little faster and firmer. Many just disable all the torque managment in the TCM and drop the desired shift times down.

    Welcome to the world of late model GM tuning!, these ECM's are pretty powerful so it will probably take some getting used to.

    Cheers,
    Ross
    I no longer monitor the forum, please either post your question or create a support ticket.

  4. #4
    Lifetime Member
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    Hmm, Kirkland, WA huh? And you have an AWD dyno...hmmm. Need to get a baseline for my TB before I s/c it this summer...
    ~Erik~
    2013 Sonic RS Manual - 1.4L I4T E78, tuned, turbo mods, etc.
    2008 TrailBlazer SS 3SS AWD Summit White - LS2 E67/T42, bolt ons, suspension, etc.
    2002 Chevy TrailBlazer LT 4X4 Summit White - 4.2L I6 P10, lifted, wheels, etc.

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