Fueling
To properly calibrate fueling on an MS41 ECU an aftermarket Wideband O2 Controller and Sensor are required. Also, it is advisable to only modify/tune either Fuel Injectors or MAF at any given time. This allows for the values most affected by low airflows at idle, such as Injector Latency and low MAF Volts, to be tuned independently.
The following variables can be logged for this purpose:
- IPW (Injector Pulswidth)
- RPM
- Load
- WBO2
- MAF Voltage
- MAF Airflow
There are 4 main tables to tune when changing fuel injectors or static fuel pressure.
Fuel Injection - Base is an old school way of setting the base value for your Injectors. This table is used during all times the engine is running. Adjust this by a percentage of your injector change as a starting point. This table in lieu of an 'injector scalar' value you may be used to in other tuning applications.
Fuel Injection - Cranking sets the IPW to be used while cranking the engine. Adjust this table based on percent difference of your new injectors.
Fuel Injection - Cranking Initial sets the IPW to be used for the initial first fuel pulse prior to sustained cranking. Adjust this table based on percent difference of your new injectors.
Fuel Injector Dead Time tries to compensate for electromechanical latency between the ECU and injector. Use the values provided by your injector manufacturer as a starting point. Usually bigger injectors have higher latency so try some higher values if no datasheet is available.
Additionally, there are 2 tables that enrich fuel when Open Loop Enrichment is active. When OLE is active, the ECU does not use the oxygen sensors to trim fuel correction.
Fuel Injection - Open Loop Enrichment adds fuel when OLE is active.
Open Loop Enrichment - Detection uses Throttle Position to determine if OLE should be activated.
*Note - My custom MS41.3 code uses Engine Load to determine if OLE should be activated.
Calculator - Injector Duty Cycle