OpenGK - Recent changes [en]

Main Page

Ardamir — Thu, 17 Sep 2026 22:38:48 GMT

← Older revision		Revision as of 22:38, 17 September 2026
Line 49:		Line 49:
	==== Siemens L4 2.0L Firmware ====		==== Siemens L4 2.0L Firmware ====
	[[SIMK43 Airflow and Load Model]]<br>		[[SIMK43 Airflow and Load Model]]<br>
	[[SIMK43 Ignition Strategy]]		[[SIMK43 Ignition Strategy]]<br>
			[[SIMK43 Fuel & Injector Control Model]]

	==== Siemens V6 2.7L Hardware ====		==== Siemens V6 2.7L Hardware ====

Fuel Injector Specifications

Ardamir — Thu, 17 Sep 2026 18:59:27 GMT

Fixed EVO injectors dead times

← Older revision		Revision as of 18:59, 17 September 2026
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	\|-		\|-
	\|4.69		\|4.69
	\|6.~~120~~		\|3.825
	\|-		\|-
	\|7.04		\|7.04
	\|5.~~232~~		\|3.270
	\|-		\|-
	\|9.38		\|9.38
	\|2.~~712~~		\|1.695
	\|-		\|-
	\|11.73		\|11.73
	\|1.~~776~~		\|1.110
	\|-		\|-
	\|14.08		\|14.08
	\|1.~~296~~		\|0.810
	\|-		\|-
	\|16.42		\|16.42
	\|0.~~912~~		\|0.570
	\|-		\|-
	\|18.70		\|18.70
	\|0.~~648~~		\|0.405
	\|}		\|}
	{\| class="wikitable"		{\| class="wikitable"

SIMK43 Fuel & Injector Control Model

Ardamir — Thu, 17 Sep 2026 15:19:49 GMT

← Older revision		Revision as of 15:19, 17 September 2026
Line 216:		Line 216:
	The choice depends on the operating state.		The choice depends on the operating state.

	=== ~~5.1~~ IP_TI_COR__N__MAF ===		=== IP_TI_COR__N__MAF ===

	The normal basic-TI correction map is:		The normal basic-TI correction map is:
Line 255:		Line 255:
	It is '''not''' the primary injector-size calibration.		It is '''not''' the primary injector-size calibration.

	=== ~~5.2~~ IP_TI_COR_IS__N__MAF ===		=== IP_TI_COR_IS__N__MAF ===

	Idle operation has a separate correction surface:		Idle operation has a separate correction surface:

SIMK43 Fuel & Injector Control Model

Ardamir — Thu, 17 Sep 2026 15:18:19 GMT

Full injection model of SIMK43

Show changes

Fuel Injector Specifications

Ardamir — Thu, 17 Sep 2026 10:03:55 GMT

Added EVO X injectors to the list and updated dead times

← Older revision		Revision as of 10:03, 17 September 2026
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	\|3.5L VQ35VHR		\|3.5L VQ35VHR
	\|OEM Nissan		\|OEM Nissan
			\|-
			\|DENSO
			Mitsubishi
			\|JME600G
			\|EV6
			\|541cc
			\|532cc
			\|8
			\|12-14Ω
			\|2.0L 4B11T
			\|OEM Mitsubishi
	\|-		\|-
	\|DENSO		\|DENSO
Line 266:		Line 277:
	\|}		\|}
	{\| class="wikitable"		{\| class="wikitable"
	\|+Mitsubishi Evo X OEM ~~525cc~~		\|+Mitsubishi Evo X OEM 532cc
	!Volts		!Volts
	!Milliseconds		!Milliseconds
	\|-		\|-
	\|4.69		\|4.69
	\|3.~~825~~		\|6.120
	\|-		\|-
	\|7.04		\|7.04
	\|3.~~270~~		\|5.232
	\|-		\|-
	\|9.38		\|9.38
	\|1.~~695~~		\|2.712
	\|-		\|-
	\|11.73		\|11.73
	\|1.~~110~~		\|1.776
	\|-		\|-
	\|14.08		\|14.08
	\|0.~~810~~		\|1.296
	\|-		\|-
	\|16.42		\|16.42
	\|0.~~570~~		\|0.912
	\|-		\|-
	\|18.70		\|18.70
	\|0.~~405~~		\|0.648
	\|}		\|}
	{\| class="wikitable"		{\| class="wikitable"

Main Page

Ardamir — Thu, 17 Sep 2026 07:55:13 GMT

Siemens L4 2.0L Firmware

← Older revision		Revision as of 07:55, 17 September 2026
(2 intermediate revisions by the same user not shown)
Line 46:		Line 46:
	[[2.0L ECM]]		[[2.0L ECM]]
	<br>		<br>

			==== Siemens L4 2.0L Firmware ====
			[[SIMK43 Airflow and Load Model]]<br>
			[[SIMK43 Ignition Strategy]]

	==== Siemens V6 2.7L Hardware ====		==== Siemens V6 2.7L Hardware ====

SIMK43 Ignition Strategy

Ardamir — Thu, 17 Sep 2026 07:49:42 GMT

Added new category

← Older revision		Revision as of 07:49, 17 September 2026
Line 1,459:		Line 1,459:

	Ignition timing is therefore simultaneously a combustion parameter, a knock-control mechanism, and one of the ECU's fastest torque-control actuators.		Ignition timing is therefore simultaneously a combustion parameter, a knock-control mechanism, and one of the ECU's fastest torque-control actuators.

			__INDEX__
			__NEWSECTIONLINK__
			[[Category:Siemens L4 2.0L]]
			[[Category:Documentation]]

SIMK43 Ignition Strategy

Ardamir — Wed, 16 Sep 2026 17:54:46 GMT

Full ignition model of SIMK43

New page

This document describes the ignition-angle and ignition-torque model implemented in the '''Siemens SIMK43 ca663056''' calibration.

It documents how the ECU calculates its Reference and Basic ignition angles, applies operating-condition corrections, represents ignition retard as a torque-efficiency quantity, converts torque requests into ignition-angle requests, incorporates knock control, applies the minimum allowable ignition angle, and determines the final spark angle independently for each cylinder.

== Index ==

__TOC__

== General Architecture ==

SIMK43 does not use a simple strategy consisting of one main ignition map followed by a small number of corrections.

Ignition timing is integrated directly into the engine torque model.

The ECU maintains two principal ignition-angle references:

* '''Reference ignition angle'''
* '''Basic ignition angle'''

The Reference angle represents the ignition timing used by the torque model as its reference point.

The Basic angle represents the normal operating ignition-angle path.

These two paths are corrected independently before entering the torque and final-spark calculations.

The overall structure is:

<pre>
ENGINE OPERATING POINT
RPM / Load / Temperature / Lambda / VVT
|
+-----------+-----------+
| |
v v
IGA_REF map IGA_BAS map
0x15CA5 0x158ED
| |
v v
Reference corrections Basic corrections
| |
v v
IGA_REF_COR IGA_BAS_COR
| |
| +-------+-------+
| | |
| v v
| Average knock Per-cylinder
| correction knock correction
| |
| v
| Basic + Avg Knock
| |
+-------+-------+
|
v
Ignition efficiency model
|
v
Torque coordinator
|
v
Requested ignition angle
|
+-------------------+
|
Basic + cylinder knock ------------------+
|
Minimum allowable ignition -------------+
|
v
FINAL PER-CYLINDER SPARK
|
v
Final average ignition
|
v
Ignition efficiency
|
v
Torque model feedback
</pre>

The important point is that ignition timing serves two purposes simultaneously:

* It determines the actual combustion phasing of the engine.
* It acts as a fast torque-control actuator.

The ignition model therefore has to describe both the physical spark angle and the amount of torque that is expected from that spark angle.

== Ignition-Angle Conventions ==

Ignition angle is expressed in crankshaft degrees.

Throughout this document:

'''IGA'''

means ignition angle.

'''degCRK'''

means crankshaft degrees.

A more advanced spark angle is numerically further toward the advanced direction.

A retarded angle is later relative to the Reference ignition angle.

SIMK43 commonly represents ignition torque loss using a positive '''retard difference''' from the Reference angle.

The fundamental relationship is:

<pre>
IGA_DIF = IGA_REF_COR - IGA
</pre>

Therefore:

<pre>
IGA_DIF = 0 deg
</pre>

means that the current ignition angle is equal to the corrected Reference angle.

A larger positive IGA_DIF means that spark has been moved further away from Reference in the retard direction.

Conceptually:

<pre>
IGA_REF_COR
|
| 0 deg retard
v
Reference spark
|
| Increasing IGA_DIF
v
More retarded spark
|
v
Lower ignition torque efficiency
</pre>

== Engine Operating Point ==

The principal ignition maps operate primarily as functions of:

* engine speed
* cylinder air charge

Cylinder air charge is expressed in:

<pre>
mg/stk
</pre>

The load quantity is therefore the same cylinder-charge state produced by the [[SIMK43 Airflow and Load Model|SIMK43 airflow/load model]].

The basic relationship is:

<pre>
Engine speed
+
Cylinder air charge
|
v
Ignition base maps
</pre>

Additional operating conditions modify the resulting ignition angles.

These include functions related to:

* intake-air temperature
* coolant temperature
* lambda
* ambient pressure
* valve timing
* transient operation
* knock control
* exhaust temperature protection

== Reference Ignition Angle ==

The principal Reference ignition-angle map is:

'''IGA_REF'''

Address:

<pre>
0x15CA5
</pre>

It is a 16 x 12 map indexed by:

* engine speed
* cylinder air charge

Its output is:

<pre>
degCRK
</pre>

Functionally:

<pre>
IGA_REF = f(RPM, MAF_CYL)
</pre>

The Reference ignition angle is not simply another normal operating spark map.

It establishes the ignition angle that the ECU uses as the reference point for ignition-related torque calculations.

Conceptually:

<pre>
RPM
+
Cylinder load
|
v
IGA_REF
0x15CA5
|
v
Reference ignition angle
</pre>

The Reference angle represents the theoretical or reference torque-producing spark angle used by the ECU's ignition-efficiency model.

It therefore acts as the '''zero-retard reference''' for the torque calculation.

=== Reference Ignition Corrections ===

The Reference ignition path contains additional corrections that modify the base Reference map before it is used by the torque model.

Identified ca663056 calibrations include:

'''IP_IGA_REF_TEMP'''

Address:

<pre>
0x15D6D
</pre>

This provides a temperature-related correction to the Reference ignition path.

Another identified correction is:

'''IP_IGA_REF_OFS_IVVT'''

Address:

<pre>
0x1942C
</pre>

This provides a VVT-related Reference ignition offset as a function of engine speed and cylinder load.

The functional structure is therefore:

<pre>
IGA_REF
|
+---- Temperature influence
|
+---- IVVT influence
|
+---- Other operating-state corrections
|
v
IGA_REF_COR
</pre>

The corrected Reference angle becomes the zero point used by the ignition-efficiency calculations.

== Basic Ignition Angle ==

The principal Basic ignition-angle map is:

'''IGA_BAS'''

Address:

<pre>
0x158ED
</pre>

It is also a 16 x 12 map indexed by:

* engine speed
* cylinder air charge

Its output is:

<pre>
degCRK
</pre>

Functionally:

<pre>
IGA_BAS = f(RPM, MAF_CYL)
</pre>

The Basic ignition angle represents the normal operating ignition path.

Conceptually:

<pre>
RPM
+
Cylinder load
|
v
IGA_BAS
0x158ED
|
v
Basic operating ignition angle
</pre>

The Basic map does not have to be identical to the Reference map.

In many operating regions, Basic can be intentionally more retarded than Reference.

The difference between them forms part of the ECU's available ignition torque reserve.

=== Basic Ignition Corrections ===

The Basic ignition path contains a larger set of operating-condition corrections.

Identified calibrations include:

'''IP_IGA_BAS_OFS_IVVT'''

Address:

<pre>
0x193EC
</pre>

This provides a VVT-dependent offset to Basic ignition timing.

'''IP_IGA_BAS_TEMP'''

Address:

<pre>
0x15A95
</pre>

This provides a temperature-related Basic ignition correction.

'''IP_IGA_BAS_TEMP_FAC'''

Address:

<pre>
0x15AD5
</pre>

This provides an additional temperature-dependent correction factor.

'''IP_IGA_BAS_AMP_COR'''

Address:

<pre>
0x159AD
</pre>

This provides an ambient-pressure-related Basic ignition correction.

'''IP_IGA_BAS_LAMB'''

Address:

<pre>
0x159CD
</pre>

This provides an additive ignition correction associated with lambda setpoint.

The functional Basic path can therefore be represented as:

<pre>
IGA_BAS
|
+---- IVVT correction
|
+---- Temperature correction
|
+---- Ambient-pressure correction
|
+---- Lambda correction
|
+---- Transient / operating-state corrections
|
v
IGA_BAS_COR
</pre>

The resulting corrected Basic angle is the normal ignition candidate before torque intervention and per-cylinder knock correction are applied.

== Ignition Torque Reserve ==

The corrected Reference and Basic ignition angles define an important torque-control quantity.

Conceptually:

<pre>
Ignition torque reserve = IGA_REF_COR - IGA_BAS_COR
</pre>

If Basic is more retarded than Reference, the ECU has the ability to increase engine torque rapidly by advancing ignition timing toward Reference.

Example:

<pre>
IGA_REF_COR = 30 deg
IGA_BAS_COR = 24 deg

Reserve = 6 deg
</pre>

The Basic engine operating point is therefore 6 degrees behind the Reference angle.

The ECU can move toward the Reference angle without waiting for a large air-path change.

Conceptually:

<pre>
More retarded More advanced

IGA_BAS_COR -----------------------------> IGA_REF_COR
| |
Normal operating Reference torque
spark spark
| |
+------------ Torque reserve --------------+
</pre>

Ignition therefore provides a very fast torque-control mechanism.

== Knock-Control Integration ==

Knock control operates in parallel with the normal Basic ignition path.

SIMK43 maintains both:

* an average knock correction
* individual per-cylinder knock corrections

These have different roles in the ignition model.

The '''average knock correction''' is used when calculating the torque efficiency associated with the Basic ignition path.

The '''individual cylinder corrections''' are applied later when determining the actual final ignition angle of each cylinder.

The structure is therefore:

<pre>
IGA_BAS_COR
|
+-----------+-----------+
| |
v v
Average knock Per-cylinder knock
correction corrections
| |
v |
Basic torque-efficiency |
calculation |
v
Final cylinder spark
</pre>

This separation allows the torque model to account for the overall torque loss caused by knock retard while still applying the necessary protection independently to each cylinder.

=== Basic Ignition Angle with Average Knock ===

For the torque model, the corrected Basic angle is combined with the average knock correction.

Conceptually:

<pre>
IGA_BAS_KNK = IGA_BAS_COR + IGA_KNK_AVG
</pre>

A knock correction in the retard direction moves the effective Basic angle later.

The ECU then calculates the retard difference between Reference and the knock-corrected Basic angle:

<pre>
IGA_DIF_BAS = IGA_REF_COR - IGA_BAS_KNK
</pre>

Negative retard differences are not physically required for the normal efficiency calculation, so the effective difference is constrained to the valid retard region.

Conceptually:

<pre>
IGA_DIF_BAS =
max(
IGA_REF_COR - IGA_BAS_KNK,
0
)
</pre>

This difference is then converted into Basic ignition torque efficiency.

== Ignition Efficiency Model ==

SIMK43 represents the effect of spark retard on torque using an ignition-efficiency model.

The principal calibration is:

'''IPM_EFF_IGA'''

Address:

<pre>
0x14FD4
</pre>

Definition:

<pre>
EFF_IGA = f(IGA_DIF)
</pre>

where:

'''IGA_DIF'''

is spark retard relative to corrected Reference ignition.

The fundamental calculation is:

<pre>
IGA_DIF = IGA_REF_COR - IGA
</pre>

followed by:

<pre>
EFF_IGA = IPM_EFF_IGA(IGA_DIF)
</pre>

Conceptually:

<pre>
Current ignition angle
|
v
Reference - Current
|
v
Ignition retard
[degCRK]
|
v
IPM_EFF_IGA
0x14FD4
|
v
Ignition torque efficiency
</pre>

When:

<pre>
IGA = IGA_REF_COR
</pre>

then:

<pre>
IGA_DIF = 0
</pre>

and ignition efficiency is approximately unity.

As ignition is retarded further from Reference, ignition efficiency decreases.

=== Meaning of Ignition Efficiency ===

Ignition efficiency represents the fraction of Reference torque that the ECU expects to remain after ignition retard.

Conceptually:

<pre>
EFF_IGA = 1.0
</pre>

means approximately full Reference ignition torque.

A lower value means the ECU expects less torque because combustion has been deliberately phased later.

For example, conceptually:

<pre>
Reference spark
IGA_DIF = 0
EFF_IGA approximately 1.0

|
v

Small retard
IGA_DIF increases
EFF_IGA decreases

|
v

Large retard
IGA_DIF increases further
EFF_IGA decreases further
</pre>

The efficiency model therefore converts an ignition-angle difference into a torque-domain quantity.

=== Basic Ignition Torque Efficiency ===

The Basic ignition path is converted into a torque-efficiency value using the average knock-corrected Basic angle.

The functional sequence is:

<pre>
IGA_BAS_COR
|
v
Add average knock correction
|
v
IGA_BAS_KNK
|
v
IGA_REF_COR - IGA_BAS_KNK
|
v
IGA_DIF_BAS
|
v
IPM_EFF_IGA
0x14FD4
|
v
EFF_IGA_BAS
</pre>

Mathematically:

<pre>
IGA_BAS_KNK = IGA_BAS_COR + IGA_KNK_AVG
</pre>

<pre>
IGA_DIF_BAS =
max(
IGA_REF_COR - IGA_BAS_KNK,
0
)
</pre>

<pre>
EFF_IGA_BAS = IPM_EFF_IGA(IGA_DIF_BAS)
</pre>

This means knock retard is fed back into the torque model.

If knock control retards ignition, the ECU does not continue assuming that the engine is producing the same torque.

The reduced spark efficiency is reflected in the calculated torque state.

=== Torque Coordinator and Requested Ignition Efficiency ===

The torque coordinator does not have to request a particular spark angle directly.

Instead, it can express the required ignition intervention as a requested ignition efficiency.

Conceptually:

<pre>
Requested engine torque
|
v
Torque coordination
|
v
Requested ignition efficiency
|
v
EFF_IGA_SP
</pre>

A requested efficiency near unity requires ignition close to the Reference angle.

A lower requested efficiency requires additional spark retard.

This creates a clean relationship between the torque-control system and the ignition system:

<pre>
Torque request
|
v
Required torque fraction
|
v
Requested ignition efficiency
|
v
Required spark retard
</pre>

=== Inverse Ignition-Efficiency Model ===

The ECU contains an inverse calibration that converts requested ignition efficiency back into the spark retard required to produce that efficiency.

The calibration is:

'''IP_IGA_DIF_SP'''

Address:

<pre>
0x15BED
</pre>

Its functional relationship is:

<pre>
IGA_DIF_TQ_REQ = IP_IGA_DIF_SP(EFF_IGA_SP)
</pre>

The structure is:

<pre>
Requested ignition efficiency
|
v
IP_IGA_DIF_SP
0x15BED
|
v
Required retard from Reference
|
v
IGA_DIF_TQ_REQ
</pre>

This is effectively the inverse of the forward ignition-efficiency model.

Forward:

<pre>
Ignition retard
|
v
IPM_EFF_IGA
|
v
Ignition efficiency
</pre>

Inverse:

<pre>
Requested ignition efficiency
|
v
IP_IGA_DIF_SP
|
v
Required ignition retard
</pre>

== Torque-Requested Ignition Angle ==

Once the required retard from Reference has been calculated, the ECU converts it back into an absolute ignition angle.

The relationship is:

<pre>
IGA_TQ_REQ = IGA_REF_COR - IGA_DIF_TQ_REQ
</pre>

The complete torque-request path therefore becomes:

<pre>
Torque request
|
v
Requested ignition efficiency
|
v
IP_IGA_DIF_SP
0x15BED
|
v
Required retard from Reference
|
v
IGA_REF_COR - retard
|
v
IGA_TQ_REQ
</pre>

This ignition angle represents the spark timing required by the torque coordinator.

=== Relationship Between Basic and Torque-Requested Spark ===

At this stage the ECU has at least two important ignition candidates.

The first is the normal operating path:

<pre>
IGA_BAS_COR
+ cylinder knock correction
+ additional cylinder-specific corrections
</pre>

The second is the torque-control path:

<pre>
IGA_TQ_REQ
</pre>

The torque coordinator must be able to reduce torque relative to the Basic path.

Therefore, under normal torque-reduction operation, the more retarded of the two candidates is selected.

Conceptually:

<pre>
Basic / knock candidate -----+
|
v
Select later
spark angle
^
|
Torque-request candidate ----+
</pre>

This allows torque intervention to retard spark below the normal Basic ignition request.

If no additional torque reduction is required, the Basic path remains dominant.

=== Ignition Torque Feedback Loop ===

The complete ignition-torque relationship therefore forms a closed loop.

The forward physical model is:

<pre>
Actual spark retard
|
v
IPM_EFF_IGA
|
v
Actual ignition efficiency
|
v
Calculated engine torque
</pre>

The inverse control model is:

<pre>
Requested torque
|
v
Requested ignition efficiency
|
v
IP_IGA_DIF_SP
|
v
Required spark retard
|
v
Requested ignition angle
</pre>

The final spark calculation then determines what angle is actually used.

That result is converted back into ignition efficiency and returned to the torque model.

Conceptually:

<pre>
Torque request
|
v
Requested efficiency
|
v
Required retard
|
v
Requested spark
|
v
Final arbitration
|
v
Actual spark
|
v
Actual efficiency
|
v
Torque model
</pre>

Ignition timing is therefore both an actuator and a feedback quantity within the torque-control system.

== Minimum Ignition Angle ==

SIMK43 also calculates a minimum permissible ignition angle.

The main ca663056 calibration involved in this path is:

'''Base Minimum Ignition Angle Difference'''

Address:

<pre>
0x15B1D
</pre>

It is a 16 x 12 map indexed by:

* engine speed
* cylinder air charge

This calibration participates in the calculation of the minimum ignition-angle limit.

The XDF identifies it as a '''minimum ignition angle difference''' rather than simply a direct final spark-angle table.

The disassembly shows that this map is processed through additional scaling and correction logic before the final minimum ignition angle is obtained.

The functional path is therefore better represented as:

<pre>
RPM
+
Cylinder load
|
v
Minimum-angle base map
0x15B1D
|
v
Scaling / corrections
|
v
Minimum allowable ignition angle
IGA_MIN
</pre>

The minimum-angle system prevents normal torque-control retard from moving spark beyond the allowed combustion-stability or protection boundary.

=== Minimum-Angle Temperature Protection ===

The minimum-angle system also contains an exhaust-temperature-related calibration:

'''IP_IGA_DIF_MIN_TEG'''

Address:

<pre>
0x15BDD
</pre>

This calibration modifies the permitted minimum ignition behaviour according to dynamic exhaust-gas temperature.

Functionally:

<pre>
Dynamic exhaust temperature
|
v
IP_IGA_DIF_MIN_TEG
0x15BDD
|
v
Minimum-angle correction
</pre>

The minimum ignition angle is therefore not simply a fixed RPM/load boundary.

It can be modified by engine thermal conditions and other operating-state corrections.

=== Interaction Between Minimum Angle and Knock Control ===

The normal minimum-angle limiter prevents torque control from requesting excessive retard.

Knock control, however, has a different priority.

If additional retard is required to protect an individual cylinder from knock, the normal torque-control minimum-angle restriction must not prevent the required protective retard.

The logic therefore distinguishes between:

* retard requested for torque control
* retard required for knock protection

Conceptually:

<pre>
Torque-control retard
|
v
Limited by normal IGA_MIN

Knock-required retard
|
v
Special protection authority
|
v
Can override normal retard restriction
</pre>

This prevents the torque-control minimum-angle system from interfering with knock protection.

== Per-Cylinder Ignition Path ==

Final spark timing is calculated individually for each cylinder.

Each cylinder receives its own knock correction.

Conceptually:

<pre>
IGA_BAS_COR
|
+--------------+--------------+
| | |
v v v
Cylinder 1 Cylinder 2 ...
knock correction knock correction
| |
v v
Basic + knock Basic + knock
candidate candidate
</pre>

The torque-request angle is common to the torque-control system, while knock correction can differ from cylinder to cylinder.

The final arbitration is therefore repeated independently for all four cylinders.

== Final Ignition Arbitration ==

The normal final per-cylinder ignition logic can be represented approximately as:

<pre>
IGA_FINAL_CYL =
max(
IGA_MIN,
min(
IGA_TQ_REQ,
IGA_BAS_COR
+ IGA_KNK_CYL
+ other cylinder corrections
)
)
</pre>

The inner selection:

<pre>
min(
IGA_TQ_REQ,
Basic + Knock
)
</pre>

selects the more retarded of the normal Basic/knock path and the torque-request path.

The outer selection:

<pre>
max(
IGA_MIN,
selected angle
)
</pre>

prevents the normal torque-control result from moving beyond the minimum allowable ignition angle.

The functional sequence is:

<pre>
Basic + cylinder knock
|
+----------------+
|
v
Torque-request angle -> Select more retarded angle
|
v
Apply minimum-angle limit
|
v
Final cylinder ignition
</pre>

Knock-protection authority modifies this normal limitation when additional knock retard is required.

=== Final Spark for Each Cylinder ===

The final result of the arbitration is four independent ignition angles:

<pre>
IGA_FINAL_CYL1

IGA_FINAL_CYL2

IGA_FINAL_CYL3

IGA_FINAL_CYL4
</pre>

These represent the actual spark-angle commands after:

* Basic ignition calculation
* Reference-based torque control
* knock correction
* minimum-angle limitation
* cylinder-specific corrections

The structure is:

<pre>
Final arbitration
|
+----------------+----------------+
| | |
v v v
Cylinder 1 Cylinder 2 Cylinder 3
final IGA final IGA final IGA
|
+---- Cylinder 4
final IGA
</pre>

=== Final Average Ignition Angle ===

The four final cylinder ignition angles are also combined into an average final ignition angle.

Conceptually:

<pre>
IGA_FINAL_CYL1
+
IGA_FINAL_CYL2
+
IGA_FINAL_CYL3
+
IGA_FINAL_CYL4
|
v
Average
|
v
IGA_FINAL_AVG
</pre>

The average angle is required because the torque model describes the overall engine rather than one individual cylinder.

=== Final Ignition Efficiency ===

Once the final average ignition angle is known, the ECU calculates ignition efficiency again.

First:

<pre>
IGA_DIF_FINAL = IGA_REF_COR - IGA_FINAL_AVG
</pre>

Then:

<pre>
EFF_IGA_FINAL = IPM_EFF_IGA(IGA_DIF_FINAL)
</pre>

The complete feedback path is:

<pre>
Final cylinder ignition angles
|
v
Average final ignition
|
v
IGA_REF_COR - IGA_FINAL_AVG
|
v
Final ignition retard
|
v
IPM_EFF_IGA
0x14FD4
|
v
Final ignition efficiency
|
v
Torque model feedback
</pre>

This is an important part of the SIMK43 torque architecture.

The torque model does not only calculate what ignition timing should be commanded.

It also recalculates the torque effect of the spark angle that actually survived final arbitration.

=== Final Spark Output and Event Scheduling ===

After the final spark angle has been calculated for each cylinder, the result is transferred to the low-level ignition event scheduler.

The ca663056 disassembly traces the ignition path all the way from the high-level ignition calculations to the crank-synchronous spark scheduling mechanism.

Functionally:

<pre>
Final per-cylinder ignition angle
|
v
Ignition output conversion
|
v
Crank-synchronous scheduler
|
v
Physical ignition event
</pre>

The scheduler converts the requested crankshaft angle into the timing required for the actual ignition event.

This is the final stage between the torque/ignition model and the ignition hardware.

== Complete Functional Sequence ==

The complete ignition path can be represented as:

<pre>
ENGINE OPERATING POINT
RPM / Load / Temp / Lambda / VVT
|
+-----------+-----------+
| |
v v
IGA_REF IGA_BAS
0x15CA5 0x158ED
| |
v v
Reference corrections Basic corrections
| |
v v
IGA_REF_COR IGA_BAS_COR
| |
| Average knock
| |
| v
| Basic + Avg Knock
| |
| v
| REF - BASIC
| |
| v
| IPM_EFF_IGA
| 0x14FD4
| |
| v
| EFF_IGA_BAS
|
|
TORQUE COORDINATOR
|
v
Torque request
|
v
EFF_IGA_SP
|
v
IP_IGA_DIF_SP
0x15BED
|
v
IGA_DIF_TQ_REQ
|
v
IGA_REF_COR - IGA_DIF_TQ_REQ
|
v
IGA_TQ_REQ
|
+--------------------------+
|
v
Basic + per-cylinder knock ------------ Final arbitration
^
|
Minimum ignition angle ---------------------+
|
v
Final cylinder ignition
|
v
Average final ignition
|
v
IGA_REF_COR - IGA_FINAL_AVG
|
v
IPM_EFF_IGA
0x14FD4
|
v
EFF_IGA_FINAL
|
v
Torque model feedback
|
v
Crank-synchronous scheduler
</pre>

== Complete Mathematical Model ==

=== Corrected Reference Angle ===

<pre>
IGA_REF_COR = IGA_REF + Reference corrections
</pre>

=== Corrected Basic Angle ===

<pre>
IGA_BAS_COR = IGA_BAS + Basic corrections
</pre>

=== Ignition Torque Reserve ===

<pre>
IGA_RESERVE = IGA_REF_COR - IGA_BAS_COR
</pre>

=== Basic Angle Including Average Knock ===

<pre>
IGA_BAS_KNK = IGA_BAS_COR + IGA_KNK_AVG
</pre>

=== Basic Retard from Reference ===

<pre>
IGA_DIF_BAS =
max(
IGA_REF_COR - IGA_BAS_KNK,
0
)
</pre>

=== Basic Ignition Efficiency ===

<pre>
EFF_IGA_BAS = IPM_EFF_IGA(IGA_DIF_BAS)
</pre>

=== Torque-Requested Retard ===

<pre>
IGA_DIF_TQ_REQ = IP_IGA_DIF_SP(EFF_IGA_SP)
</pre>

=== Torque-Requested Ignition Angle ===

<pre>
IGA_TQ_REQ = IGA_REF_COR - IGA_DIF_TQ_REQ
</pre>

=== Normal Final Per-Cylinder Spark ===

<pre>
IGA_FINAL_CYL =
max(
IGA_MIN,
min(
IGA_TQ_REQ,
IGA_BAS_COR
+ IGA_KNK_CYL
+ cylinder corrections
)
)
</pre>

Knock-protection logic can modify the normal minimum-angle restriction when further protective retard is required.

=== Final Average Ignition Angle ===

<pre>
IGA_FINAL_AVG =
Average(
IGA_FINAL_CYL1,
IGA_FINAL_CYL2,
IGA_FINAL_CYL3,
IGA_FINAL_CYL4
)
</pre>

=== Final Retard from Reference ===

<pre>
IGA_DIF_FINAL = IGA_REF_COR - IGA_FINAL_AVG
</pre>

=== Final Ignition Efficiency ===

<pre>
EFF_IGA_FINAL = IPM_EFF_IGA(IGA_DIF_FINAL)
</pre>

== Functional Interpretation ==

The SIMK43 ignition system can be divided into five principal functional layers.

'''1. Reference Spark Model'''

The ECU calculates the corrected Reference ignition angle representing the zero-retard point used by the ignition torque model.

'''2. Basic Spark Model'''

The ECU calculates the corrected Basic ignition angle representing the normal operating spark path.

'''3. Ignition Torque Model'''

The difference between Reference and actual spark is converted into ignition torque efficiency.

'''4. Torque Intervention'''

Requested torque is converted into requested ignition efficiency, then into required spark retard and finally into a requested ignition angle.

'''5. Final Spark Arbitration'''

Torque-request spark, Basic spark, knock correction and minimum-angle protection are combined separately for each cylinder before the final ignition event is scheduled.

Ignition timing is therefore simultaneously a combustion parameter, a knock-control mechanism, and one of the ECU's fastest torque-control actuators.

SIMK43 Airflow and Load Model

Ardamir — Wed, 16 Sep 2026 09:28:57 GMT

Fixed typos

← Older revision		Revision as of 09:28, 16 September 2026
(One intermediate revision by the same user not shown)
Line 1:		Line 1:
	This document describes the airflow and engine-load model implemented in the '''Siemens SIMK43 ca663056''' calibration.		This document describes the airflow and engine-load model implemented in the '''Siemens SIMK43 ca663056''' calibration, which should also apply on all other G4GC CVVT calibrations.

	It documents how the ECU measures incoming air using the hot-film MAF sensor, independently calculates airflow using the intake-manifold model, determines cylinder air charge, supervises the measured and modeled airflow paths, and integrates the resulting load value into the torque, ignition and fueling systems.		It documents how the ECU measures incoming air using the hot-film MAF sensor, independently calculates airflow using the intake-manifold model, determines cylinder air charge, supervises the measured and modeled airflow paths, and integrates the resulting load value into the torque, ignition and fueling systems.

	~~The description is based on the latest verified '''ca663056 XDF''', the available '''SAM2000 / SAM2K metadata''', and the '''ca663056 C167 disassembly'''.~~

	The SAM metadata is used primarily to establish the intended engineering meaning, units and functions of the calibrations. Actual ca663056 addresses and execution behaviour are taken from the ca663056 calibration and disassembly.

	== Index ==		== Index ==
Line 69:		Line 65:
	SIMK43 should therefore not be regarded simply as a MAF-based ECU.		SIMK43 should therefore not be regarded simply as a MAF-based ECU.

	It is more accurately described as a '''model-based cylinder-charge control system using the ~~HFM~~ sensor as its primary airflow measurement'''.		It is more accurately described as a '''model-based cylinder-charge control system using the MAF sensor as its primary airflow measurement'''.

	== 2. Airflow and Load Units ==		== 2. Airflow and Load Units ==
Line 78:		Line 74:

	* Unit: V or internal ADC representation		* Unit: V or internal ADC representation
	* Meaning: electrical output of the ~~HFM~~ sensor.		* Meaning: electrical output of the MAF sensor.

	'''Engine airflow'''		'''Engine airflow'''
Line 1,191:		Line 1,187:
	The ECU converts actual cylinder air charge into estimated torque and requested torque back into required cylinder air charge.		The ECU converts actual cylinder air charge into estimated torque and requested torque back into required cylinder air charge.

	Physical ~~HFM~~ measurement and a parallel intake-manifold model are used together to determine the amount of fresh air available for combustion and to provide a consistent load quantity for the torque, ignition and fueling systems.		Physical MAF measurement and a parallel intake-manifold model are used together to determine the amount of fresh air available for combustion and to provide a consistent load quantity for the torque, ignition and fueling systems.

SIMK43 Airflow and Load Model

Ardamir — Wed, 16 Sep 2026 09:21:43 GMT

Created page with "This document describes the airflow and engine-load model implemented in the '''Siemens SIMK43 ca663056''' calibration. It documents how the ECU measures incoming air using the hot-film MAF sensor, independently calculates airflow using the intake-manifold model, determines cylinder air charge, supervises the measured and modeled airflow paths, and integrates the resulting load value into the torque, ignition and fueling systems. The description is based on the latest..."

New page

This document describes the airflow and engine-load model implemented in the '''Siemens SIMK43 ca663056''' calibration.

It documents how the ECU measures incoming air using the hot-film MAF sensor, independently calculates airflow using the intake-manifold model, determines cylinder air charge, supervises the measured and modeled airflow paths, and integrates the resulting load value into the torque, ignition and fueling systems.

The description is based on the latest verified '''ca663056 XDF''', the available '''SAM2000 / SAM2K metadata''', and the '''ca663056 C167 disassembly'''.

The SAM metadata is used primarily to establish the intended engineering meaning, units and functions of the calibrations. Actual ca663056 addresses and execution behaviour are taken from the ca663056 calibration and disassembly.

== Index ==

__TOC__

== 1. General Architecture ==

The SIMK43 airflow system contains two parallel representations of engine airflow:

* '''Measured airflow''' derived from the physical hot-film MAF sensor.
* '''Modeled airflow''' calculated from engine speed, manifold conditions, valve overlap, temperature and ambient pressure.

These paths ultimately describe the same physical quantity: the mass of fresh air entering the engine.

The MAF sensor measures air travelling through the intake tract, while the combustion system ultimately requires an estimate of the amount of fresh air entering an individual cylinder.

The overall architecture is:

<pre>
AIR ENTERING ENGINE
|
+--------------+--------------+
| |
v v
HFM / MAF SENSOR INTAKE MANIFOLD MODEL
| |
v v
Sensor linearization RPM / pressure / VVT
| temperature / ambient
v |
Measured airflow v
[kg/h] Modeled engine airflow
| [kg/h]
| |
v v
Convert using RPM Convert using RPM
| |
v v
Measured cylinder Modeled cylinder
air charge air charge
[mg/stk] [mg/stk]
| |
+--------------+--------------+
|
v
AIRFLOW SUPERVISION
|
v
FINAL CYLINDER LOAD
[mg/stk]
|
+-----------------+-----------------+
| | |
v v v
IGNITION FUELING TORQUE
|
actual load -> torque
|
torque request -> load
</pre>

SIMK43 should therefore not be regarded simply as a MAF-based ECU.

It is more accurately described as a '''model-based cylinder-charge control system using the HFM sensor as its primary airflow measurement'''.

== 2. Airflow and Load Units ==

Siemens uses the term ''MAF'' for several related quantities. The engineering unit must therefore always be considered when interpreting a calibration or internal calculation.

'''MAF sensor signal'''

* Unit: V or internal ADC representation
* Meaning: electrical output of the HFM sensor.

'''Engine airflow'''

* Unit: kg/h
* Meaning: total fresh-air mass flowing through the complete engine intake.

'''Cylinder air charge'''

* Unit: mg/stk
* Meaning: fresh-air mass entering one cylinder during one intake event.

'''Torque'''

* Unit: Nm
* Meaning: indicated or effective engine torque.

The two principal airflow domains are:

<pre>
MAF_KGH
</pre>

and:

<pre>
MAF_CYL
</pre>

They describe the same airflow from two different perspectives.

'''MAF_KGH''' measured in '''kg/h''' represents the total airflow of the complete engine.

'''MAF_CYL''' measured in '''mg/stk''' represents the mass of fresh air entering one cylinder during one intake event.

Most combustion-related calibration maps operate in the cylinder-charge domain.

== 3. Measured Airflow Path ==

=== 3.1 MAF Sensor Characteristic ===

The primary MAF characteristic in ca663056 is:

'''ID_MAF_TAB'''

Address:

<pre>
0x11B4E
</pre>

This table converts the electrical MAF sensor representation into total engine mass airflow.

Its output is expressed in kg/h.

Functionally:

<pre>
MAF electrical signal
|
v
ID_MAF_TAB
0x11B4E
|
v
Engine airflow
[kg/h]
</pre>

The ca663056 disassembly directly references address '''0x11B4E''' during initialization of the MAF conversion path, confirming that the table is actively used for MAF conversion.

The sensor characteristic can therefore be represented as:

<pre>
MAF_RAW = ID_MAF_TAB(V_MAF)
</pre>

This is the stage responsible for converting the physical MAF sensor signal into an engineering airflow quantity.

== 4. MAF Acquisition and Signal Conditioning ==

The ECU does not use a single instantaneous MAF sample directly as engine load.

The ca663056 disassembly shows that MAF measurements are accumulated over repeated acquisition periods and subsequently divided by the number of samples.

The measurement path therefore performs averaging before the airflow value is used elsewhere.

Conceptually:

<pre>
MAF_AVG = Average(MAF_RAW)
</pre>

The averaged airflow then passes through an operating-point-dependent correction.

The relevant calibration is:

'''IP_MAF_KGH_MES_FAC'''

Address:

<pre>
0x193EC
</pre>

SAM defines the function as:

<pre>
IP_MAF_KGH_MES_FAC = f(N, TPS_SEG)
</pre>

where:

* '''N''' = engine speed
* '''TPS_SEG''' = throttle operating region

The output of this map is a '''dimensionless correction factor'''.

The corrected measured airflow can therefore be represented as:

<pre>
MAF_MES_COR = MAF_AVG x F_MAF(N, TPS)
</pre>

The resulting quantity remains in:

<pre>
kg/h
</pre>

and represents the ECU's corrected physical measurement of total engine airflow.

== 5. Conversion from Engine Airflow to Cylinder Air Charge ==

The combustion model itself does not primarily operate in kg/h.

After corrected measured airflow has been obtained, the ECU converts total engine airflow into cylinder air charge using engine speed.

For a four-cylinder, four-stroke engine:

<pre>
Intake events per hour = (RPM / 2) x 4 x 60
</pre>

Therefore:

<pre>
MAF_CYL [mg/stk] =
MAF_KGH [kg/h] x 1,000,000
--------------------------------
(RPM / 2) x 4 x 60
</pre>

For a four-cylinder engine this simplifies to:

<pre>
MAF_CYL [mg/stk] = 8333.333 x MAF_KGH [kg/h] / RPM
</pre>

Example:

<pre>
400 kg/h at 3000 rpm

MAF_CYL = 1111 mg/stk
</pre>

At twice the engine speed:

<pre>
400 kg/h at 6000 rpm

MAF_CYL = 556 mg/stk
</pre>

The same total engine airflow therefore represents a different cylinder load depending on engine speed.

This distinction is fundamental to the SIMK43 load model.

== 6. Definition of Engine Load ==

For the remainder of the combustion-control system, the principal load quantity is cylinder air charge.

Conceptually:

<pre>
LOAD = MAF_CYL
</pre>

with units:

<pre>
mg/stk
</pre>

The basic conversion chain is:

<pre>
MAF signal
|
v
Engine airflow
[kg/h]
|
v
RPM conversion
|
v
Cylinder charge
[mg/stk]
|
v
Engine load
</pre>

This cylinder-charge quantity is used as the load coordinate by many ignition, fueling and torque-model functions.

== 7. Independent Intake-Manifold and Cylinder-Filling Model ==

In parallel with the physical MAF measurement, SIMK43 independently calculates airflow using a model of the intake system and the engine's cylinder-filling characteristics.

The core cylinder-flow model consists of two calibrations.

=== 7.1 IP_EFF_VOL_OFS ===

Address:

<pre>
0x1245E
</pre>

Definition:

<pre>
IP_EFF_VOL_OFS [kg/h] = f(N, VO)
</pre>

where:

* '''N''' = engine speed
* '''VO''' = valve overlap

This calibration provides the base airflow offset of the cylinder-filling model.

=== 7.2 IP_EFF_VOL_SLOP ===

Address:

<pre>
0x1252A
</pre>

Definition:

<pre>
IP_EFF_VOL_SLOP [kg/(h*hPa)] = f(N, VO)
</pre>

This calibration provides the pressure-dependent slope of the cylinder-filling model.

Together, the two maps describe the relationship between effective manifold pressure and cylinder airflow.

== 8. Offset and Slope Representation of Cylinder Filling ==

SIMK43 does not represent cylinder filling using one conventional percentage-VE table.

Instead, airflow is represented approximately as a linear relationship between an effective pressure quantity and airflow.

The basic relationship is:

<pre>
MAF_MDL = O + S x P_EFF
</pre>

where:

<pre>
O = IP_EFF_VOL_OFS(N, VO)
</pre>

and:

<pre>
S = IP_EFF_VOL_SLOP(N, VO)
</pre>

The units verify the relationship:

<pre>
kg/h + [kg/(h*hPa)] x hPa = kg/h
</pre>

The ca663056 disassembly loads the offset and slope calibrations as separate coefficients used in the same airflow calculation.

The effective pressure term should not automatically be interpreted as a raw MAP sensor-like value. It belongs to the larger manifold model and represents the pressure-domain state used by the cylinder-flow equation.

Functionally:

<pre>
RPM
+
Valve overlap
+
Effective manifold pressure
|
v
Offset / slope cylinder model
|
v
Predicted engine airflow
[kg/h]
</pre>

== 9. Effect of Valve Overlap ==

Both base airflow coefficients depend on valve overlap.

<pre>
O = f(N, VO)

S = f(N, VO)
</pre>

The model is therefore explicitly aware of camshaft timing.

Changing valve overlap changes the predicted relationship between manifold pressure and cylinder airflow.

Conceptually:

<pre>
Valve timing
|
v
Valve overlap
|
v
Cylinder filling characteristic
|
v
Predicted airflow
</pre>

VVT therefore forms part of the physical air model rather than being treated only as an independent actuator.

== 10. Temperature Correction of Cylinder Filling ==

Cylinder filling changes with intake air temperature and engine thermal state.

The principal temperature-dependent corrections are:

'''IP_EFF_TIA_FAC'''

Address:

<pre>
0x15539
</pre>

Definition:

<pre>
F_TIA = f(N, MAF)
</pre>

This represents the effect of intake-air temperature on the cylinder-filling model.

'''IP_EFF_TCO_FAC'''

Address:

<pre>
0x154F9
</pre>

Definition:

<pre>
F_TCO = f(N, MAF)
</pre>

This represents the effect of coolant temperature on the cylinder-filling model.

The ECU combines the temperature influences into a common correction quantity.

The resulting correction is filtered before it is applied to the cylinder-flow model.

The relevant filtering calibration is:

'''IP_CRLC_EFF_VOL_COR'''

Address:

<pre>
0x154ED
</pre>

Definition:

<pre>
CRLC_VE = f(N)
</pre>

The resulting thermal correction can therefore be represented conceptually as a low pass filter:

<pre>
F_THERM = LPF[f(TIA, TCO, N, LOAD)]
</pre>

where:

'''LPF''' represents the filtering applied by the ECU.

== 11. Ambient-Pressure Compensation ==

The base cylinder-flow characteristic is also corrected according to ambient pressure.

The relevant calibrations are:

'''IP_EFF_VOL_OFS_AMP'''

Address:

<pre>
0x1251E
</pre>

Definition:

<pre>
F_OFS_AMP = f(AMP_AD)
</pre>

and:

'''IP_EFF_VOL_SLOP_AMP'''

Address:

<pre>
0x125EA
</pre>

Definition:

<pre>
F_SLOP_AMP = f(AMP_AD)
</pre>

Both outputs are '''dimensionless correction factors'''.

'''AMP_AD''' represents the ECU's adapted ambient-pressure state.

The ambient-pressure corrections modify both the offset and slope of the cylinder-flow characteristic.

== 12. Corrected Cylinder-Flow Coefficients ==

The complete cylinder-flow coefficients can be represented as follows.

The base offset is:

<pre>
O_0 = IP_EFF_VOL_OFS(N, VO)
</pre>

The base slope is:

<pre>
S_0 = IP_EFF_VOL_SLOP(N, VO)
</pre>

The effective offset is:

<pre>
O_EFF = O_0 x F_OFS_AMP
</pre>

The effective slope is:

<pre>
S_EFF = S_0 x F_THERM x F_SLOP_AMP
</pre>

The disassembly shows the slope being corrected by the filtered thermal correction and then by the ambient-pressure correction.

The offset is separately corrected by its own ambient-pressure factor.

The final modeled airflow equation is:

<pre>
MAF_MDL_KGH = O_EFF + S_EFF x P_EFF
</pre>

This is the central cylinder-filling relationship of the SIMK43 airflow model.

== 13. Manifold Filling and Pressure-Ratio Model ==

The effective pressure term used by the cylinder-flow equation comes from the larger intake-manifold model.

SAM identifies several associated functions relating to:

* throttle effective area
* pressure ratio across the throttle
* upstream pressure
* intake-system pressure loss
* intake-air temperature
* manifold filling dynamics
* predicted manifold state

One relevant calibration is:

'''IP_FAC_AR_RED_COR'''

Definition:

<pre>
IP_FAC_AR_RED_COR = f(PQ)
</pre>

where:

'''PQ''' represents a pressure-ratio quantity.

Additional functions include:

'''ID_MAF_FAC_OFS'''

<pre>
ID_MAF_FAC_OFS = f(PQ_ESTIM)
</pre>

and:

'''ID_MAF_FAC_SLOP'''

<pre>
ID_MAF_FAC_SLOP = f(PQ_ESTIM)
</pre>

These functions describe nonlinear airflow behaviour associated with the pressure ratio across the intake restriction.

Another manifold-model coefficient is:

'''IP_MAF_MDL_CON_1'''

Definition:

<pre>
C_MAN = f(TIA)
</pre>

Its engineering unit is approximately:

<pre>
s/m
</pre>

This coefficient participates in the physical manifold-filling model.

The intake-manifold model can therefore be represented as:

<pre>
Throttle effective area
|
+---- Upstream pressure
|
+---- Pressure ratio
|
+---- Intake temperature
|
+---- Manifold filling dynamics
|
v
Effective manifold pressure state
|
v
Cylinder offset / slope model
|
v
Predicted engine airflow
</pre>

The modeled airflow is therefore derived from pressure and filling behaviour rather than from a simple throttle-angle-to-load lookup.

== 14. Intake-System Pressure Loss ==

The intake model also accounts for pressure loss between the outside atmosphere and the pressure available upstream of the throttle.

SAM defines:

'''IP_AMP_DEC'''

as:

<pre>
DELTA_P_INTAKE = f(MAF_THR)
</pre>

As airflow increases, the pressure loss through the intake tract also increases.

Conceptually:

<pre>
P_UPSTREAM = AMP_AD - DELTA_P_INTAKE
</pre>

This upstream pressure participates in the throttle pressure-ratio and manifold-filling calculations.

The model therefore does not assume that atmospheric pressure is always fully available at the throttle inlet.

== 15. Modeled Airflow to Modeled Cylinder Charge ==

Once the model has calculated total engine airflow in kg/h, that airflow is converted into cylinder charge using the same physical relationship as the measured-airflow path.

For the four-cylinder engine:

<pre>
MAF_CYL_MDL [mg/stk] = 8333.333 x MAF_MDL_KGH [kg/h] / RPM
</pre>

The measured and modeled paths therefore converge into the same engineering domain:

<pre>
mg/stk
</pre>

This allows the two airflow estimates to be compared, supervised and substituted.

== 16. MAF Pulsation Supervision ==

The physical MAF signal can become unreliable when intake-flow pulsation or reverse-flow effects become sufficiently large.

SIMK43 therefore contains a dedicated MAF-pulsation supervision system.

One of the principal calibrations is:

'''IP_MAF_PULS_MAX'''

Address:

<pre>
0x12F50
</pre>

Definition:

<pre>
MAF_PULS_MAX = f(N)
</pre>

The system also contains maximum-difference and hysteresis parameters.

The ECU evaluates the spread of the sampled MAF signal.

That spread is converted into the cylinder-charge domain using engine speed.

The calculated pulsation is then compared with the permissible pulsation limit.

Conceptually:

<pre>
MAF samples
|
v
Maximum / minimum spread
|
v
Convert spread to mg/stk
|
v
Compare with IP_MAF_PULS_MAX
|
v
MAF pulsation state
</pre>

The pulsation state participates directly in airflow-source supervision.

It is therefore part of the functional airflow model and not merely a diagnostic function.

== 17. Measured-Airflow and Modeled-Airflow Arbitration ==

SIMK43 contains source-selection logic between the measured and modeled airflow paths.

Functionally:

<pre>
If measured airflow is accepted:
MAF_WORK_KGH = MAF_MES_KGH

If measured airflow is rejected:
MAF_WORK_KGH = MAF_MDL_KGH
</pre>

During normal operation, the physical MAF measurement is the primary airflow source.

When the measured signal is considered unsuitable because of pulsation, faults or other fallback conditions, the independently calculated manifold-model airflow can replace it.

The airflow architecture therefore contains two complete sources for engine airflow:

<pre>
Measured MAF airflow Modeled manifold airflow
| |
+--------------+--------------+
|
v
Source selector
|
v
Working airflow

</pre>

== 18. Final Cylinder-Load Determination ==

Following airflow supervision, the ECU maintains several representations of cylinder charge.

The principal sources include:

* measured-air-derived cylinder charge
* manifold-model-derived cylinder charge
* filtered or alternate cylinder-charge representations
* fallback cylinder charge

These ultimately produce one effective load quantity:

<pre>
MAF_CYL_WORK
</pre>

with units:

<pre>
mg/stk
</pre>

The rest of the combustion-control system uses this working cylinder-charge state without needing to know whether its source originated from the MAF measurement or the manifold model.

== 19. Reference Torque Model ==

The principal forward relationship between cylinder charge and torque is:

'''IP_TQI_REF'''

Address:

<pre>
0x14D68
</pre>

Definition:

<pre>
TQI_REF = f(N, MAF_CYL)
</pre>

where:

* '''MAF_CYL''' is cylinder fresh-air charge in mg/stk.
* '''TQI_REF''' is reference indicated torque in Nm.

The function therefore represents:

<pre>
Cylinder air charge
[mg/stk]
|
v
IP_TQI_REF
|
v
Reference indicated torque
[Nm]
</pre>

This map describes the torque the engine is expected to produce from a given amount of cylinder fresh air.

== 20. Torque Loss Model ==

Indicated torque is not identical to torque available at the crankshaft.

SIMK43 separately models friction and pumping losses.

The principal calibration is:

'''IP_TQFR'''

Address:

<pre>
0x14AE0
</pre>

Definition:

<pre>
TQFR = f(N, MAF_CYL)
</pre>

This represents base friction and pumping losses as a function of engine speed and cylinder load.

Conceptually:

<pre>
TQ_EFFECTIVE =
TQI
- TQ_FRICTION
- TQ_PUMPING
- TQ_ACCESSORY
- other losses
</pre>

The torque system therefore combines the calculated indicated combustion torque with independently calculated engine losses.

== 21. Inverse Torque-to-Air Model ==

SIMK43 also contains the inverse relationship between torque and cylinder air charge.

The relevant calibration is:

'''IP_MAF_SP'''

Address:

<pre>
0x12F5C
</pre>

Definition:

<pre>
MAF_SP = f(N, TQI_SP)
</pre>

The output is:

<pre>
mg/stk
</pre>

This calibration converts desired indicated torque into the cylinder air charge required to produce that torque.

The two principal torque/air relationships are therefore:

'''Forward model'''

<pre>
MAF_CYL -> TQI
</pre>

through:

'''IP_TQI_REF'''

and:

'''Inverse model'''

<pre>
TQI_SP -> MAF_CYL_SP
</pre>

through:

'''IP_MAF_SP'''

Together, these functions form the central air-to-torque and torque-to-air relationship of SIMK43.

== 22. Air-Charge Control Objective ==

Once the torque system has calculated a desired cylinder charge:

<pre>
MAF_CYL_SP
</pre>

it can be compared with the estimated actual cylinder charge:

<pre>
MAF_CYL_ACT
</pre>

The conceptual air-control error is:

<pre>
E_AIR = MAF_CYL_SP - MAF_CYL_ACT
</pre>

The air-path controller can then act on the available air-control actuators (mainly the IAC Valve, as the throttle is driven by a steel cable) in order to move actual cylinder charge toward requested cylinder charge.

This illustrates why the SIMK43 torque-control structure is fundamentally based around '''cylinder air charge''' rather than throttle angle alone.

== 23. IVVT Airflow Prediction ==

SIMK43 contains an additional airflow estimator associated with the IVVT system.

One relevant calibration is:

'''IP_MAF_IVVT_1'''

Address:

<pre>
0x193A4
</pre>

Definition:

<pre>
MAF_IVVT = f(N, TPS)
</pre>

Its output represents calculated airflow for the VVT-related airflow-prediction path.

SAM also identifies:

* '''IP_MAF_IVVT_2''' - alternate airflow calculation used when a TPS error exists.
* '''IP_MAF_TPS_FAC''' - throttle-position weighting.
* '''IP_MAF_ADD_ISAPWM''' - estimated additional airflow through the idle-air actuator.
* '''IP_MAF_FAC_TIA''' - intake-air-temperature correction.

This auxiliary IVVT airflow estimator should be distinguished from the main manifold and cylinder-filling model.

The primary physical cylinder model is based on:

* '''IP_EFF_VOL_OFS'''
* '''IP_EFF_VOL_SLOP'''

The IVVT airflow calculation represents an additional prediction path associated with VVT, throttle and idle-air operating conditions.

== 24. End-to-End Functional Sequence ==

=== 24.1 Measured-Air Path ===

<pre>
MAF electrical signal
|
v
ID_MAF_TAB
0x11B4E
|
v
Total engine airflow
kg/h
|
v
Sampling and averaging
|
v
Operating-point MAF correction
IP_MAF_KGH_MES_FAC
|
v
Corrected measured airflow
kg/h
|
v
RPM conversion
|
v
Measured cylinder air charge
mg/stk
|
v
Airflow / load source supervision
|
v
Final working cylinder load
mg/stk
</pre>

=== 24.2 Modeled-Air Path ===

<pre>
RPM
Valve overlap
Ambient pressure
IAT
Coolant temperature
Throttle / manifold state
|
v
IP_EFF_VOL_OFS
IP_EFF_VOL_SLOP
|
v
Temperature correction
|
v
Ambient correction
|
v
Corrected offset and slope
|
v
Effective manifold pressure
|
v
Predicted engine airflow
kg/h
|
v
RPM conversion
|
v
Predicted cylinder charge
mg/stk
|
v
Airflow / load source supervision
</pre>

Both paths therefore converge before the main combustion-control functions.

== 25. Complete Mathematical Model ==

=== 25.1 Measured Airflow ===

<pre>
MAF_RAW = ID_MAF_TAB(V_MAF)

MAF_AVG = Filter(MAF_RAW)

MAF_MES_COR = MAF_AVG x F_MAF(N, TPS)
</pre>

=== 25.2 Measured Cylinder Charge ===

<pre>
MAF_CYL_MES =
8333.333 x MAF_MES_COR / RPM
</pre>

=== 25.3 Base Modeled Cylinder-Flow Coefficients ===

<pre>
O_0 = IP_EFF_VOL_OFS(N, VO)

S_0 = IP_EFF_VOL_SLOP(N, VO)
</pre>

=== 25.4 Corrected Cylinder-Flow Coefficients ===

<pre>
O_EFF = O_0 x F_OFS_AMP

S_EFF = S_0 x F_THERM x F_SLOP_AMP
</pre>

=== 25.5 Modeled Airflow ===

<pre>
MAF_MDL_KGH = O_EFF + S_EFF x P_EFF
</pre>

=== 25.6 Modeled Cylinder Charge ===

<pre>
MAF_CYL_MDL = 8333.333 x MAF_MDL_KGH / RPM
</pre>

=== 25.7 Working Engine Load ===

<pre>
MAF_CYL_WORK =
Select(
MAF_CYL_MES,
MAF_CYL_MDL,
MAF_CYL_FALLBACK
)
</pre>

=== 25.8 Forward Torque Model ===

<pre>
TQI_REF =
IP_TQI_REF(
RPM,
MAF_CYL_WORK
)
</pre>

=== 25.9 Inverse Torque Model ===

<pre>
MAF_CYL_SP =
IP_MAF_SP(
RPM,
TQI_SP
)
</pre>

== 26. Functional Interpretation ==

The SIMK43 airflow architecture can be divided into four principal functional layers.

'''1. Measurement'''

The physical MAF signal is converted into corrected total engine airflow in kg/h.

'''2. Physical Model'''

An independent intake-manifold model predicts airflow using manifold conditions, engine speed, valve overlap, temperature and ambient pressure.

'''3. Load Estimation'''

Measured and modeled airflow are converted into cylinder charge in mg/stk and supervised to produce the ECU's effective working load.

'''4. Torque Coordination'''

The ECU converts actual cylinder air charge into estimated torque and requested torque back into required cylinder air charge.

Physical HFM measurement and a parallel intake-manifold model are used together to determine the amount of fresh air available for combustion and to provide a consistent load quantity for the torque, ignition and fueling systems.

File:Simk43 iga graph full.png

Ardamir — Tue, 15 Sep 2026 22:50:57 GMT

Ardamir uploaded File:Simk43 iga graph full.png

New page

Full flowchart

Aftermarket Tune Labeling Convention

Ardamir — Sat, 05 Sep 2026 17:51:41 GMT

Added tuning labeling for M7.9.7 tunes

@@ Line 1: / Line 1: @@
-== Tune Identifier Legend ==
+== SIMK43 Tune Identifier Legend ==
 {| class="wikitable" style="text-align:left;"
@@ Line 23: / Line 23: @@
 |}
-== Example Breakdown ==
+=== Example Breakdown ===
 '''Identifier:''' <code>KANES-42CDGPI98L</code>
@@ Line 35: / Line 34: @@
 * '''98''' → Optimized for 98 RON
 * '''L''' → Launch Control Enabled