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Thread: 3 bar SD OS MAF fail setup and octane table behavior

  1. #1
    Tuner homebuilt's Avatar
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    3 bar SD OS MAF fail setup and octane table behavior

    Hello,

    Does anyone know how to setup the 3 bar SD OS with regards to the MAF fields?

    I don't have a MAF sensor physically installed and I don't know if you are to still set the MAF to fail like you would for VE tuning calibration?

    Without a sensor present would the PCM observe a signal > 0 htz to cause it to fail or would it just stay at the lowest value in the MAF Hz table?

    Also, the SD OS states that it maintains the function of the high and low octane tables. If I set the MAF to fail would this still divert to the low octane table? How would I control what spark table the PCM is using during tuning?

    Lastly what would the effect be on this OS be if steady state was prevented by changing the Steady State parameters under Airflow -> Dyanamic ?

  2. #2
    Tuner homebuilt's Avatar
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    My car will be running again in a few days. If no one knows the answers to my questions I could also do some trial and error tests to see how the VCM is using the MAF and spark tables.

    Another thing I didn't mention is that my VE table values the last time the engine ran seemed low but it had two fried plug wires and it was misfiring. I would have expected that to create a perceived lean condition and I would have increased the VE values to get back to the commanded Lambda (while actually causing it to be rich as my black plugs confirmed).

    I will post the tune tomorrow in case anyone can offer some insight.
    Last edited by homebuilt; 05-28-2012 at 07:36 PM.

  3. #3
    Advanced Tuner oakley6575's Avatar
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    There are plenty of tuning tutorials around here. Read through them so you understand how to properly set up open loop, closed loop, SD, and MAF tunes. Take a look at ls1tuningguide.com
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  4. #4
    Tuner homebuilt's Avatar
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    Thank you for the link. This is a nice handy site which I had not run across before. However I read through everything and didn't find anything I didn't already know. My question is specific to the speed density (SD) 3 bar OS. I don't know how this OS is coded with regards to the MAF sensor and spark advance tables.

    For example, I don't know if you should or should not set the MAF to fail with this OS. Or if it even makes any difference in the operation. Also with a regular OS failing the MAF forces the VCM to to the low octane spark table. I would like to know how the speed density (SD) 3 bar OS is using the tables and if you can force it to use one or the other while dialing in the tune.

  5. #5
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    3 Bar SD = Speed Density = no MAF and both timing tables will be used
    Last edited by orange ss; 05-29-2012 at 12:26 PM.

  6. #6
    Tuner homebuilt's Avatar
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    So no matter what, the SD OS ignores the MAF tables?

    For steady state VE tuning with this SD OS is it still beneficial to lock-out steady state to avoid transient fuel modifiers from being used?

    My tune is attached for reference.

  7. #7
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    Quote Originally Posted by homebuilt View Post
    So no matter what, the SD OS ignores the MAF tables?
    yes, that's the premise behind speed density and why you fail the MAF to enter that mode

  8. #8
    Tuner homebuilt's Avatar
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    I'm sorry. Perhaps I didn't word my question very well. I understand the two ways to force a normal operating system tune to operate in speed density mode.

    My question is: With 3 bar speed density only operating system, what are the particular MAF settings required? (i.e. no error reported, fail at 0 with MIL etc.)

    Or does this operating system ignore the MAF fields all together?

    I had low VE values which seemed unusual and I want to be sure that I rule out this MAF question as a possible cause. I didn't know if it was sitting at the lowest value in the table and using that in the calculations or something.

    Also, if this operating system can maintain the function of the high and low octane spark tables I didn't want to set the MAF to fail and limit myself to the low octane table. Again this is if this OS has the ability to fail the MAF which I don't know.

    If no one knows the answer I can test a few things out once the car is running but I was hoping to avoid having to figure that out if it is already known.

  9. #9
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    MAF Frequency fail = 0
    error reported, no light

    3 Bar SD OS is SD only but recommned to fail MAF manually as well.

  10. #10
    Tuner homebuilt's Avatar
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    Thank you.

    If the MAF is failed then wouldn't this cause the VCM to default to the low octane spark table?

    One of the features mentioned with the 3 bar SD OS was that it kept that functionality.

  11. #11
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    apparently timing table functionality will remain, Bill recommended to fail MAF manually

  12. #12
    Senior Tuner LSxpwrdZ's Avatar
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    On most of the SD stuff I do it doesn't really matter what the DTC's are set at to still run off the VE table only. I've tried setting multiple Custom SD OS's to 0-MIL On First Error; 2-No MIL; and 3-No Error Reported and they all function the same. I normally use the 2-No MIL or 3-No Error Reported on the SD setups I tune. Timing tables work like stock with the custom SD OS's.
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  13. #13
    Tuner homebuilt's Avatar
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    Very helpful. Thank you.

  14. #14
    Tuner homebuilt's Avatar
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    Along the same 3 bar setup line (scanner), I followed the help file directions, I don't have a boost PID or anything and the histograms were stopping at 105 lap. I figured out how to get it to work by creating manual histograms using the 3 bar PID.