FB MDRED 4.50 Functional Description
This function provides the injection suppression levels corresponding to the target torque request misol_w (relative to the indicated
Engine torque mibas_w, which results from the static ignition angle zwbase and basic lambda lambas).
A hysteresis must be used to ensure that there is no "bouncing" when selecting the reduction stages (cf. sub-function "HYST").
Cutting off the decimal places ("floor function") results in the new reduction level. in the sub-function "BBRED" *giggity* it is determined whether injection suppression
is allowed (B_mdee) and whether overrun fuel cut-off takes place (B_sa).
The real reduction level redist results from a max selection between redbas (base reduction level through bank shutdown
or by misfire detection) and the reduction level redsol calculated from misol.
Sub-function HYST: Hysteresis to prevent bouncing of the skip stage
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The hysteresis is determined by the difference between REDHYUC and REDHYOC and the offset of the hysteresis, based on the old value of
redsol, established by (1-REDHYOC). REDHYUC must always be greater than REDHYOC. Exceeds the calculated skip level redzst
the current value redsol by more than 1-REDHYOC (at redzst_w>redsol(k-1)-REDHYOC)
or REDHYUC (at redzst_w <= redsol(k-1)-REDHYOC) stages,
then the next fade-out level must be selected.
Subfunction BBRED: operating conditions of the torque intervention via injection suppression
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The characteristic curve REDZEM as a function of the motor temperature can be used to determine from which reduction stage the reduction occurs
injection suppression is actually allowed. If the calculated reduction level redneu is less than that in the characteristic curve REDZEM
preset value, ignition angle intervention is activated. Injection suppression is only possible if redsol>=redze
(see above) is or if the requested torque misol_w is smaller than the torque mizwmn that can be realized at the latest ignition angle
and the condition like B_ska, B_dknolu, B_nmax or B_sab & CREDSTU (1st bit) is set. In addition, the B_stend must be set so that
is not hidden during the starting process and the engine can run up. With B_asr =1, the cylinder suppression is then possible,
if the 0th bit of CREDSTU is also set to 1. Otherwise the ignition angle intervention is limited to zwmin and none
Cylinder suppression is possible.
Initiation of overrun fuel cut-off without prior torque reduction by cylinder suppression (1st bit of CREDSTU = 0): If misol_w
is smaller than mizwmn_w and B_sab is set, the condition B_sa is set and the target reduction stage redsol is equal to REDMX,
so that fuel cut-off takes place.
Sequential fuel cut-off (1st bit of CREDSTU=1): When the current reduction stage reaches the applicable threshold REDMXSA
or exceeds and B_sab is set, the condition B_sa is set and the target reduction level redsol is equal to REDMX,
so that fuel cut-off takes place.
In the case of MSR intervention (B_msr = 1), fuel cut-off is prohibited.
APP MDRED 4.50 application notes
Typical value:
REDMX = number of cylinders
REDHYOC = 0.5 (with simultaneous injection and ignition interventions)
REDHYUC = 0.6 (with simultaneous injection and ignition interventions)
MDHYEZ = 5Nm
CREDSTU[0] = 0 (cylinder suppression not possible with ASR)
Characteristic REDZEM (typical value see picture below)
This characteristic defines the threshold between injection suppression and ignition intervention. Depending on the engine temperature can be applied
from which reduction stage the injection suppression no longer leads to excess catalytic converter temperature.
https://files.s4wiki.com/docs/from the R4-5V PDF
Need to collect the FR for cross referencing versions of ME7 and their functions.
PRJ doesn't seem to want to educate.. .
My post was better than Yours.
"Booo"
