Summary Notes

[joecar]

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).
If at any time PCM transitions OL then B3605, B3647 become 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.