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Thread: How to go MAFless

  1. #21
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    Joe

    Since I haven't done either AutoVE or Calc.MAFT I guess I will go with the newer Calc.MAFT and skip the MAF correction. I will be doing this probably next week and post back how that goes.

    What about the custom OS for SD? We are planning to remove the whole MAF assembly and put in a simple (two wire) IAT sensor instead (less air restriction).

    From the COS LS1 Tutorial I gather I need COS 02030001. Will the COS take care of ignoring the MAF by itself without me having to fail it? Where Can I download it and is there any benefit from doing the OS swap?

    thanks

    Jorge

  2. #22
    Joe (Moderator) joecar's Avatar
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    Calc.MAFT:
    are you going OL (wideband only) or CL (LTFT and wideband)...?
    If you're going OL then you have to modify the Calc.MAFT procedure as follows:
    - in calc_pids.txt edit CLC-00-315 to use CALC.WO2BEN instead of CALC.SELBEN, <-- you don't have to do this if you're SD/MAF-less.
    - in your scantool VE map use CALC.WO2BEN as the pid on the Data tab;
    and like you said, do the VE correction portion and ignore the MAF calculation portion.

    COS:
    yes run a COS because in SD (MAF DTC present) this retains the adaptive spark (sliding between HO and LO spark tables as knock is detected);
    in OL it also gives you very good control over OL fueling.
    You will still need a MAF DTC to trigger, and physically removing the MAF will do this, altho you may have to set C6001 P0101,2,3 to 1-Trip, and C2903 to 1 time.
    02030001 comes with you're V7 software install...
    the 02030001 file is "empty", you full flash it first, and then from your last tune file you do a cal-only flash to populate the flashed COS with your tables...
    and then you have to edit B3647 and fix any out-of-range parameters in the Custom segment.

    If you run SD with the non-COS then you lose the adaptive spark feature (i.e. with MAF DTC present, the PCM runs from the LO spark table).
    Last edited by joecar; September 16th, 2013 at 06:34 PM.

  3. #23
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    Found the COS. I guess I am going that way. Thanks for all the info.

    I will surely have more questions before I do the actual process but I want to read some first.

    Best regards,

    Cheers from Puerto Rico

  4. #24
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    Joe

    What do you mean when you say that the COS gives m better control over Open Loop fueling? Do you recommend this? I like the idea of dealing with one specific sensor vs 2 approximate sensors. How do I get the pcm to use the Wideband reading and ignore the ltft?

    I have always thought that the adaptive spark is not an issue for me since I am using 104 octane fuel. So I have both HO and LO the same.

    Thanks

  5. #25
    Joe (Moderator) joecar's Avatar
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    COS has table B3647 "Open Loop Commanded Fuel" which has the form RPM x MAP...

    compare this to table B3605 which has form ECT x MAP.

    The COS replaces B3605 with B3647.

  6. #26
    Joe (Moderator) joecar's Avatar
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    If you have HO and LO the same, it might be simpler for you to run the non-COS stock OS...

    with the stock OS, when a MAF DTC is present, the PCM runs from the LO table.

  7. #27
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by noesfacil View Post
    ...

    How do I get the pcm to use the Wideband reading and ignore the ltft?

    ...
    To do the Calc.MAFT procedure in OLSD (i.e. Open Loop and MAF-less):

    a. set your tune to disable CL/LTFT/STFT (B3801, B4205, B4206);

    b. make sure your MAF will fail (C6001, C2903);

    c. in your scantool VE map use CALC.WO2BEN as the Data pid;

    d. do the VE correction (using CALC.WO2BEN as the correction factor);

    e. ignore the MAF calculation (i.e. CLC-00-315 does not need to be modified since you're ignoring it).

  8. #28
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    B3647 sounds very interesting and more intuitive to work with. I think I'll go the COS route because of that.

    With regards to my question about the pcm reading the wideband values, what I was wandering is once you tune and get your ve tables right, does the pcm need feedback from the Wideband for operating the engine. But Now I think I get it. Use the Wideband to get the VE right using Calc.MAFT. Once calibrated the engine will only use the VE tables, RPM and MAP values to calculate comanded fuel while ignoring MAF and LTFT/STFT.

    Is this correct?

    By the way, thanks again for your patience :>
    Last edited by noesfacil; September 17th, 2013 at 05:37 AM.

  9. #29
    Joe (Moderator) joecar's Avatar
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    No, the PCM does not read the wideband...

    The PCM reads the narrowband O2 sensors and calculates trims (STFT and LTFT) which it applies, and repeats in closed loop manner.

    The wideband is read by you (via your FlashScan V2)... you use the wideband lambda to calculate and apply a correction factor to the VE table.



    Yes, correct: fail the MAF (DTC triggers), disable CL/LTFT/STFT, use WO2BEN (calculated from wideband lambda) to correct VE using Calc.MAFT procedure.

    Yes, correct, if you leave the MAF failed and leave CL/LTFT/STFT disabled, then PCM will run OLSD (OL = open loop, SD = speed-density/MAF-less).



    No problem.

  10. #30
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    Got it.

    Thanks for confirming. I'm definitely giving a try to OLSD using the COS.

    I'll keep you posted on how it goes.

    Thanks

    J

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