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Thread: Summary Notes

  1. #31
    Joe (Moderator) joecar's Avatar
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    Apr 2003


    Yes, thanks to all who have contributed their experiments results, and to all who have explained to me the fine points.

  2. #32
    Member Laychut's Avatar
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    Jan 2011

    Default Great stuff!

    Hi Joecar,
    I am only new to tuning and this summary post is great. You have answered a truck load of questions I had. Thank you very much!

  3. #33
    Joe (Moderator) joecar's Avatar
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    Apr 2003


    No worries, thanks for the feedback, this thread is meeting its intended function

  4. #34
    Joe (Moderator) joecar's Avatar
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    Apr 2003


    Updated the calc_pids.txt file in post #2, added a pid for calculating cylinder airmass from GM.VETABLE_DMA.


  5. #35
    Lifetime Member
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    Oct 2003


    Quote Originally Posted by Steve Bryant View Post
    I am reviewing, correcting my own misunderstandings and re-learning a lot of the concepts about tuning using EFILive. I've been involved with EFILive on an on-again ... off-again basis since 2005. This thread contains so much distilled wisdom. My hat is off to all!!!


    I agree with Steve on this one. This thread needs to be stickied (stuck? ) in more than a single subforum. There is an amazing amount of info here - thanks, joecar!! You guys need to broaden it's access....just a thought.


  6. #36
    Joe (Moderator) joecar's Avatar
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    Apr 2003


    Hey Joel, how's it going

    Thanks, any comments from you guys are welcome... I'm hoping to tidy it up a little, and possibly add spark timing relationships;.

    I'll add links in the other subforums to this thread.

  7. #37
    Joe (Moderator) joecar's Avatar
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    Apr 2003

    Default SOL (semi-open loop)

    SOL (semi-open loop)

    enabled via:
    - OS: B4206
    - COS: always enabled

    if enabled, SOL is active only during OL;

    SOL uses STFT to trim to stoich cells in B3605 or B3647;
    for non-stoich cells in B3605 or B3647 SOL does not trim;
    if PE enables while SOL trimming, if PE is richer then stoich, you will see PE fueling (i.e. the richer of the active tables);

    SOL can function only if trimming to stoich is possible, otherwise it won't function.
    Last edited by joecar; August 19th, 2015 at 10:50 AM.

  8. #38
    Joe (Moderator) joecar's Avatar
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    Apr 2003

    Default Injector Flowrate Calcularions

    Quoted from this thread: Calculating-Injector-Flow-rate

    Marcin's injector flowrate spreadsheet is attached to this post (scroll to bottom of post).

    The math behind this is as follows (for those who want to know)...


    R0 = injector's rated flowrate measured at pressure P0
    P0 = pressure at which the injector's rated flowrate R0 was measured (see Note below)
    FP = regulator's gauge pressure, also known as regulator's base pressure.

    MAP = manifold absolute pressure
    BARO = barometric absolute pressure = 101.3 kPa at sea level = 100 kPa approx. a little above sea level
    MANVAC = manifold vacuum = BARO - MAP

    gauge pressure = absolute pressure - BARO = value shown by pressure gauge
    absolute pressure = gauge pressure + BARO

    Pressure difference across an injector: this is the difference in the absolute pressures above and below the injector.

    An unreferenced regulator has its pressure set constant; this pressure is FP (gauge) or FP + BARO (absolute).

    A MAP-referenced regulator has a reference hose connected to the intake manifold,
    so its pressure has MAP added to it; this pressure is FP + MAP (gauge) or FP + BARO + MAP (absolute);
    with reference hose removed, this pressure becomes FP + BARO (guage) or FP + BARO + BARO (absolute).

    The flowrate of an injector is directly proportional to the squareroot of the pressure difference across the injector (this is the Bernoulli pressure relationship).

    Note on Injector Flowrate Measurement:
    when R0 is measured on an injector flow bench, P0 is actually the pressure difference across the injector:
    absolute pressure above injector = P0 + BARO; absolute pressure below injector = BARO; so then difference = P0.

    Note regarding 1997-1998 Y-car:
    The FPR is
    not MAP-referenced (follow the reference hose to verify it sees atmosphere/BARO).

    Unreferenced Regulator (e.g. 1998-2002 F-car, 1997+ Y-car)

    Pressure difference (of absolute pressures) across injector = (FP + BARO) - (MAP) = FP + BARO - MAP = FP + MANVAC

    IFR = R0 * sqrt
    ((FP + MANVAC) / P0) = varies/slopes with MANVAC

    At the rail, absolute pressure is FP + BARO, so gauge pressure is FP.
    --> Directly measure FP at rail with engine running (FP should be constant).

    The spreadsheet calculates this equation (Example 1, post #3).

    MAP-Referenced Regulator (e.g. trucks)

    Pressure difference (of absolute pressures) across injector = (FP + BARO + MAP) - (MAP) = FP + BARO

    IFR = R0 * sqrt((FP + BARO) / P0) = constant/flat regardless of MANVAC

    At the rail, absolute pressure is FP + BARO + MAP, so gauge pressure is FP + MAP.

    Remove reference hose, regulator is now exposed to barometric pressure (so MAP = BARO),
    and rail absolute pressure is FP + BARO + BARO, so gauge pressure is FP + BARO.
    --> With reference hose removed, directly measure FP + BARO at rail with engine running.

    The spreadsheet calculates this equation at MANVAC=0 if measured FP + BARO is entered (Example 2, post #3).


    Rail pressure is measured in psi, and MAP or MANVAC is measured in kPa.
    You need to convert one to the units of the other before calculating IFR.

    Convert psi to kPa by multiplying by (100/14.5).

    14.5 psi = 100 kPa

    If injectors are rated in lb/hr:
    convert lb/hr to g/s by multiplying by 0.125998 (can round to 0.1260).

    1 lb/hr = 0.1260 g/s

    If injectors are rated in cc/min:
    convert cc/min to g/min by first multiplying by density of gasoline (typically 0.73 g/cc), and then dividing by 60.

    1 cc/min = 0.0122 g/s (depending on density of gasoline)

    Attached Files Attached Files
    Last edited by joecar; April 14th, 2016 at 08:58 AM.

  9. #39
    Lifetime Member Steve Bryant's Avatar
    Join Date
    Feb 2004


    I have now read through and researched these summary notes probably ten plus times in the past several months and now I consider them to be akin to the Rosetta Stone for the LS1B PCMs. At least as far as using EFILive Scan and Tune the Powertrain Control Module.

    So for anyone who is a new or even seasoned tuner, I'll say don't give up if all of this seems complicated, etc. It is complicated, but it can be so very rewarding for those who want to modify their engines, make their transmissions (automatics) shift differently, etc. This is great stuff!


  10. #40
    Join Date
    Feb 2019


    joecar, this is great there any way you/someone could convert the param/table numbers to current numbers since some of these were merged or renumbered.

    LS3 Manual 6 spd E38 os:12633056
    Texas Speed 1 7/8" headers w/3" exhaust
    Texas Speed cam 229/236 .629/.615 112 LSA
    Hi-Ram intake stock injectors 90mmTB

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