Application and evidence scope
This page records the S4 2.7T examples in S4Wiki revision 5324. M-box means 8D0907551M; L-box means 8D0907551L. A note explicitly described as M-box has that scope. Confirm the precise software and definition before using an address or a reported stock figure.
2.7T injector-flow calculation
S4Wiki gives the following starting estimate, with displacement in litres and injector volume flow in cc/min at the actual differential fuel pressure:
KRKTE [ms/%] = 74 * (engine displacement / cylinder count) / injector flow
For the cited 2.671-litre six-cylinder engine:
KRKTE [ms/%] = approximately 32.9 / injector flow [cc/min]
Flow at a different pressure:
Q_new = Q_rated * sqrt(deltaP_new / deltaP_rated)The cited stock S4 pressure is 4 bar above manifold pressure. Use the injector’s pressure difference, test-fluid convention and rating conditions consistently when converting a flow figure.
| Source example | Flow at 4 bar | Approximate KRKTE from the estimate | Stock calibration reported by S4Wiki |
|---|---|---|---|
| S4 / A6 / allroad injectors | 349 cc/min | 0.0944 ms/% | 0.0978 ms/% |
| RS4 injectors | 480 cc/min | 0.0686 ms/% | 0.0676 ms/% |
The difference between an estimate and a reported calibration is part of the example, not a reason to replace the stock value automatically. The source explains that the formal injector calculation uses mass-flow characterisation and a test-fluid correction; converting a volume-flow rating requires the corresponding fluid density.
The engineering value in milliseconds is distinct from its raw representation. S4Wiki lists CPU-clock-dependent conversion factors and flags incorrect factors in older definition files. Verify the examined software’s timing conversion before interpreting or editing raw KRKTE data.
MAF offset and load consequences
The source distinguishes Bosch and Hitachi MAF-offset examples: 200 for the cited Bosch conversion and zero for the Hitachi case. Confirm the actual fitted sensor and file. Use the offset-aware relationship in the shared fueling guide when that conversion applies.
On the documented M-box, the source places fuel trims and adaptations in the fuel-quantity calculation; they do not themselves rescale the MAF-derived load and boost request. A MAF correction acts earlier in the air/charge model. This distinction helps explain why correcting an injector-flow error through the MAF can move the calculated load and pressure model.
Narrowband and two-bank context
The S4 discussion describes stock narrowband feedback near lambda one and the need for an independent wideband measurement of richer operation. Retain each bank’s short- and long-term correction information and the learning state with a comparison. This measurement statement belongs to that arrangement; establish another application’s sensor/control strategy separately.
M-box definition and lambda-path traps
| Item | Source-specific observation | Review action |
|---|---|---|
| LAMFA torque axis | The source flags a 2.7T axis-range problem equivalent to 0.5–1.0% where 50–100% is intended | Inspect raw axis data, conversion and input semantics; state whether a repair changes the data or its definition |
| ZKLAMFAW | M-box example address 0x1C3EE; source reports a 0.5-second stock time constant and an older XDF mislabel as ZKWLAFWL / percentage | Treat the displayed label and unit as a definition to verify |
| ZKWLAFWL | The source locates the actual M-box warm-up blending time constant at 0x18F6A | Keep it distinct from the enrichment-target filter |
| DLBTS versus KFDLBTS | The source identifies a 2D DLBTS in the M-box, not the 3D KFDLBTS found in some discussions | Match the function variant and dimensions before reusing an explanation |
The source describes driver/knock/warm-up enrichment being combined and filtered before the final comparison with component-protection lambda. Log the relevant intermediate and final targets when an edit seems delayed or inactive. The two addresses above are M-box reference observations, not a general address list for L-box or other ME7.1 software.
Source context and adaptation
Adapted, paraphrased and reorganised from S4Wiki contributors’ Tuning, revision 5324, under Creative Commons Attribution 4.0 International. This wiki adds scope labels, cross-links and interpretation notes. The cited software observations have not been independently reproduced by this wiki.
Source sections: Injector calibration and MAF scaling, LAMFAW, Component-protection enrichment.
Sources
Curated reference notes. Applicability follows the cited sources; hardware testing by this wiki is not implied.
- S4Wiki: Tuning — source for expanded ME7 references. S4Wiki contributors; Creative Commons Attribution 4.0 International. Paraphrased, expanded and reorganised by Tuning Wiki. Source revision oldid 5324; accessed 2026-11-10.