Parameter roles
MS4X describes MS45 fuel-mass calculation before conversion to injection time. Entry points include:
| Role | Names |
|---|---|
| Lambda target | ip_lamb_bas_[1/2]; ip_lamb_fl__n |
| Injector characteristic | c_fac_mff_ti_stnd_[1/2] |
| Global time correction | c_ti_as |
| Latency / minimum time | ip_ti_add_dly; c_ti_min; c_ti_min_thd |
| Starting fuel mass | ip_mffpr_cst; ip_mff_cst |
Bracketed labels abbreviate groups. MS4X reference.
Choose one explained injector-calibration basis
Start by writing down what each quantity represents and where the proposed correction belongs. Distinguish a characteristic used during calculation from a global correction at another stage. Applying the same flow adjustment at two stages can compound it: two multipliers of 0.5 produce 0.25, not 0.5. This arithmetic is an illustration of double counting, not a recommended MS45 setting.
Keep the injector manufacturer’s pressure/voltage data with the calibration. The shared injector guide explains why a flow ratio cannot determine latency. Check actual table units before comparing starting maps with another controller.
Test starts, feedback and load separately
Build cold-start comparisons at similar coolant temperature, soak time and battery voltage, then evaluate warm restarts and idle separately. Record when the lambda signal becomes useful and which feedback state is active. Keep the learned-state record so that an adaptation change is not mistaken for a direct table effect.
The MS45.0 and MS45.1 pages describe their differing sensor/learning context. For a high-load evaluation, compare target and measured lambda using an appropriate measurement and retain fuel-delivery evidence.
Idle validation
Use an idle test matrix covering temperature, A/C and transmission load. Record the selected target and actual speed, as well as available air-actuator and ignition data. Review each applicable state when changing an idle target; the resulting driveability is the validation, rather than the fact that a single table was edited.
Sources and scope
Original reference notes by Tuning Wiki, informed by the linked MS4X Wiki pages. MS4X Wiki contributors and the authors credited by each linked project remain the source authors. Sources checked 10 November 2026. Suggested validation steps and worked arithmetic are editorial guidance; they are not a tested calibration or a claim of hardware verification.
- Siemens MS45 (revision 23142).