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Thread: Summary Notes

  1. #1
    Joe (Moderator) joecar's Avatar
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    Default Summary Notes

    Here are various summary notes relating mostly to LS1B...
    Last edited by joecar; September 6th, 2012 at 07:40 AM.

  2. #2
    Joe (Moderator) joecar's Avatar
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    Default Airflow and Airmass

    My current understanding:


    GM.MAF
    GM airflow [g/s].
    When MAF faults, this shows PCM calculated expected value (based on VE).

    SAE.MAF

    CARB airflow [g/s].
    When MAF faults, this shows actual value.

    GM.DYNAIR

    PCM calculated airflow [g/s] based on VE.
    Used in MAF rationality test and in MAF failed mode (speed density).


    GM.DYNCYLAIR
    PCM calculated cylinder airmass [g/cyl] based on VE.

    GM.DYNCYLAIR_DMA

    Internal PCM calculated cylinder airmass [g/cyl] based on VE.

    GM.CYLAIR_DMA
    Internal PCM calculated cylinder airmass [g/cyl] based on MAF.

    CALC.CYLAIR

    Scantool calculated cylinder airmass [g/cyl] based on MAF.
    {SAE.MAF.gps}*
    15/{SAE.RPM}.
    (the 15 comes from 120/8 where 8 is the cylinder count)


    GM.VETABLE_DMA
    Internal PCM lookup of VE [g*K/kPa].


    CALC.VE
    Scantool calculated VE [% and g*K/kPa] based on MAF, MAP, IAT, RPM.
    Comes with the scantool; not sure where the constants came from.
    Close in values to CALC.VEN (see below), but not sufficiently close.


    CALC.VEN
    Scantool calculated VE [%, g*K/kPa] based on MAF, MAP, DAT, RPM.
    Not corrected (i.e. no BEN correction).
    Requires definition in calc_pids.txt file, see attached for example.

    CALC.VET
    Scantool calculated VE [%, g*K/kPa] based on MAF, MAP, DAT, RPM.
    Includes correction (BEN selected from LTFT and/or wideband).
    Requires definition in calc_pids.txt file, see attached for example.

    CALC.MAFN
    Scantool calculated MAF [g/s] based on VE, MAP, DAT, RPM.
    Not corrected (i.e. no BEN correction).
    Requires definition in calc_pids.txt file, see attached for example.

    CALC.MAFT
    Scantool calculated MAF [g/s] based on VE, MAP, DAT, RPM.
    Includes correction (BEN selected from LTFT and/or wideband).
    Requires definition in calc_pids.txt file, see attached for example.

    CALC.VEDCA
    Scantool calculated VE [g*K/kPa] based on GM.DYNCYLAIR_DMA;
    Requires definition in calc_pids.txt file, see attached for example.

    CALC.DCAVE
    Scantool calculated cylinder airmass [g/cyl] based on GM.VETABLE_DMA;
    Requires definition in calc_pids.txt file, see attached for example.
    Attached Files Attached Files
    Last edited by joecar; April 14th, 2016 at 06:48 AM.

  3. #3
    Joe (Moderator) joecar's Avatar
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    Default Dynamic Air Temperature (DAT)

    GM.DYNAIRTMP_DMA
    Internal PCM calculated blended and filtered air charge temperature [C, F].

    GM.CHRGTEMP_DMA
    Internal PCM calculated blended air charge temperature before being filtered [C, F].

    CALC.DAT
    Scantool conversion of GM.DYNAIRTMP_DMA to various temperature units [C, F, K, R];
    this pid is for convenience (its short name fits easier on charts/gauges and in calc pids).
    Requires definition in calc_pids.txt file, see previous post for example.

    If those are to be used in the Ideal Gas Law equation P.V = n.R.T = (m/M).R.T they must first be converted to [K].

    Blending: see table B4901 Charge Temperature Blending.
    Filtering: see table B4902 Charge Temperature Filter.
    Last edited by joecar; April 14th, 2016 at 06:57 AM.

  4. #4
    Joe (Moderator) joecar's Avatar
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    Default VE/MAF and OL/CL

    Wideband reports the same EQR as commanded EQR if these are all true:
    - B3601 is the correct stoichiometric AFR for the fuel being used,
    - B4001 IFR and injector characterization tables are correct,
    - when/if PCM uses VE: B0101 VE is correct,
    - when/if PCM uses MAF: B5001 MAF is correct.

    PCM calculates cylinder airmass from:
    - above B0120: MAF,
    - below B0120: MAF (steady throttle/airflow) and/or VE (transient throttle/airflow),
    - in SD (MAF-less, MAF DTC present): VE.

    MAF can be disabled by failing it (i.e. an immediate MAF DTC is required).
    VE can be disabled by setting the B0120 dynamic air threshold to zero.

    VE/MAF determine airmass.
    OL/CL determine commanded EQR.

    SD/MAF are orthogonal to OL/CL, there are 6 combinations of these:
    - OL SD
    - OL MAF-only
    - OL MAF/VE
    - CL SD
    - CL MAF-only
    - CL MAF/VE

    ( SD refers to VE-only )
    ( MAF/VE refers to: MAF during steady state, VE during transient )

    PCM also uses airmass to determine ignition timing and transmission [torque signal] pressure.

    PCM determines commanded EQR from:
    - CL: closed loop feedback trimming to stoichiometric (EQR 1.000),
    - OL: the richest EQR from the EQR tables active at that moment:
    -- B3605 OLFA (OL only) (see note below),
    -- B3647 OLFA (OL only) (COS) (see note below),
    -- B3618 PE (if PE has enabled from B3608-B3616, B3619-B3626),
    -- B3659 (if PP has enabled from B3652-B3658),
    -- B3603 (if EP has enabled from B1601-B1603),
    -- COTP (if COTP has been enabled by B0701-B0705) (I don't see a table for COTP EQR, but it typically is 1.25 EQR).

    When PCM is in CL and transitions to PE (i.e. CL-PE), B3605, B3647 are not active (those are active only in OL),
    this means B3618 determines commanded EQR in CL-PE mode (if PP/EP/COTP are not active).


    The various protection mode EQR's are reflected in the commanded EQR.
    The PCM selects the richest EQR from the EQR tables active at that moment.

    The PCM performs all fueling lookups/computations in EQR units.
    The PCM converts airmass and commanded EQR to fuelmass using B3601 (stoichiometric AFR).
    The PCM converts fuelmass to injector pulsewidth using the injector tables.

    PCM uses OL in any of those situations:
    - cold,
    - CL is disabled,
    - during EVAP and CAT testing (OL-Drive),
    - during an O2S fault condition on either bank (OL-Fault).

    (there seems to be multiple OL modes: pure OL, OL-Drive, OL-Fault)

    PCM uses CL mode:
    - when enabled (B3801, B4205) and the switch point (B4501) can be met by the NBO2,
    - when PE is enabled from CL mode, the PCM retains CL mode during PE,
    - in CL-PE, negative LTFT's are zeroed, LTFT's are then frozen, the resulting LTFT's are applied.

    PE mode:
    - is not exclusive of CL mode (i.e. can have CL-PE),
    - can be active during CL (but trimming will not occur if commanded EQR is not stoich);
    - during CL-PE/WOT, the LTFT's are applied (negative LTFT's are rounded up to zero first).

    PCM retains CL mode when transitioning to PE (i.e. B3605, B3647 are not active during CL-PE).

    The PCM may also use SOL (semi open/closed loop) to trim using STFT's during OL in these situations:
    - OEM: if B4206 is enabled, when B3605 contains EQR 1.
    - COS: if B4206 is enabled, when B3647 contains EQR 1.
    - COS: if B4206 is not present, when B3647 contains EQR 1.


    Last edited by joecar; August 21st, 2017 at 06:42 PM.

  5. #5
    Lifetime Member Chevy366's Avatar
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    Default

    Good stuff there joecar .
    2005 1500 HD , Custom OS3 SD tune .
    2006 Trailblazer
    Dinosaurs and Plants gave their lives so that we may drive , long live fossil fuel .

  6. #6
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Quote Originally Posted by joecar View Post
    I'm still trying to find a good description for these:

    GM.DYNAIRTMP_DMA
    Internal PCM calculated blended air charge temperature [K].

    GM.CHRGTEMP_DMA
    How is this different...?

    I am beginning to think that it is the same? Perhaps DYNAIRTMP.DMA does not include the the Charge Temperature filter...Would be nice to know. Any ideas on how to test it?
    Good work Joe!
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  7. #7
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Quote Originally Posted by joecar View Post

    PCM determines AFR from:
    - CL: closed loop feedback trimming to stoichiometric AFR (B3601),
    - OL: the richer of: B3605, B3647 (COS), and B3618 (if PE has enabled from B3608-B3616).

    Joe, this is still a little confusing to me. I agree in OL it selects the richer of B3605 and B3618. But in CL, OL utilizes B3618..regardless of B3605. Remember my little experiment?

    The various protection mode AFR's are reflected in the commanded AFR.
    The PCM selects the richest AFR from the AFR tables active at that moment.

    PCM uses OL when:
    - cold,
    - at WOT,
    - in PE,
    - during throttle/airflow transients,
    - CL is disabled.
    - during EVAP (OL-Drive) Depending on OS.

    VE/MAF determine airmass.
    OL/CL determine commanded AFR.

    SD/MAF are orthogonal to OL/CL (there exists 4 combinations of these).

    PCM also uses airmass to determine ignition timing and transmission pressure.
    Joe, again great work. I don't want to 'muddy' up your work with too many asterisks or exceptions, but the PE vs OLFA still seems to be the case. Perhaps the EVAP is just in the 2002..since no one else seems to comment on it..
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  8. #8
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by WeathermanShawn View Post
    Joe, again great work. I don't want to 'muddy' up your work with too many asterisks or exceptions, but the PE vs OLFA still seems to be the case. Perhaps the EVAP is just in the 2002..since no one else seems to comment on it..
    Thanks for all comments...

    I want to make sure I wrote it down correctly (with no stupid typos).

    Ok, I'll add those and reword... I am curious that no one commented on EVAP.
    Last edited by joecar; August 19th, 2015 at 11:13 AM.

  9. #9
    Joe (Moderator) joecar's Avatar
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    Default Stoichiometric AFR trimming

    Changing the stoich AFR effects the calculated fuelmass, but it does not effect trimming to the actual stoich of the fuel being used.

  10. #10
    Joe (Moderator) joecar's Avatar
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    Default Calculating VE from MAF


    VE[g*K/kPa]


    The units [VE] are shorthand for [g*K/kPa]

    VE[g*K/kPa] is also called "normalized airmass" (i.e. normalized for pressure/temperature).


    Per cylinder VE[VE]:
    VE[VE] = {SAE.MAF.gps}*{CALC.DAT.K}/{SAE.MAP.kPa}/{SAE.RPM}*120/NUMCYL

    When
    NUMCYL=8: the per cylinder VE[VE] becomes:
    VE[VE] = {SAE.MAF.gps}*
    {CALC.DAT.K}/{SAE.MAP.kPa}/{SAE.RPM}*15

    VE[VE] includes the factor
    /NUMCYL in order to obtain per cylinder VE[VE].
    VE[VE] depends on MAF, MAP, DAT, RPM, and
    is independent of cylinder volume.

    For math derivation see post #103 here: New-Tuning-Tutorial-WeathermanShawn


    VE[%]

    VE[%] = {SAE.MAF.gps}*{CALC.DAT.K}/{SAE.MAP.kPa}/{SAE.RPM}*3445.2/displacement

    where displacement is engine displacement in [L]

    VE[%] has the factor
    /NUMCYL in both numerator and denominator, so it cancels out.
    VE[%] depends on MAF, MAP, DAT, RPM and
    engine displacement (or cylinder volume multiplied by number of cylinders).

    Note:
    If you use VE[VE] (i.e. g*K/kPa) you do not need to know engine displacement anymore...
    the actual VE table does not use displacement (the tunetool uses it to display VE[%] if you have opted for % VE units).


    For math derivation see post #104 here: New-Tuning-Tutorial-WeathermanShawn


    DAT[K]

    DAT[K] = {GM.DYNAIRTMP_DMA.C}+273.15


    Math derivation:

    post #27 here: DYNAIRTMP_DMA-vs-CHRGTEMP_DMA
    posts #103,4 here: New-Tuning-Tutorial-WeathermanShawn


    Note:

    Take note that VE[%] is dependent on engine displacement, whereas VE[g*K/kPa] is not.
    Last edited by joecar; April 14th, 2016 at 08:44 AM.

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