User Torque Limits


Emtron’s recent release of the V2.19.0 firmware in the latest Emtune has given the ECU a huge range of options for the controlling an engines output.  For a few years, the ECU has had the ability to control torque through many functions, however this was always within a dedicated function or as part of an OEM based application build.   This ultimately reduced the flexibility and limited the ability of the user’s imagination to apply this in a customized way.  For generic motorsport applications, there was a lot of power the ECU possessed that could not be leveraged. 

The introduction of a totally new “User Torque Limits” section has given huge flexibility to leverage Torque limiting features.  In simple terms, the User Torque Limits are exactly that.  There are now five (5) fully user configurable torque limits which can be used for any purpose in the ECU.  As displayed in Screenshot 1, once enabled a label-controlled torque limit will become active. 

Screenshot 1: Torque Limit Control – User 1


Screenshot 2 shows the main setup.  This is where the strat type is set, whether the Torque is normalised to the gear ratio and which user output channel is controlling when the torque limit becomes active. 


Screenshot 2: Setup – Torque Limit


Once the Torque Limit Setup is complete there is a 16x12 cell count table that can be used to enter the desired torque target based on nearly any channel in the ECU.  There is also a Torque Limit Correction table that allows this torque target to be manipulated by a set percentage from the table.  When the appropriate User Output channel output status becomes active the torque limit becomes active.  The ECU will then monitor the torque output from the engine and apply the strategy method configured to limit the torque.  As shown in screenshot 3 there is some unpacking needed of what is happening.  The example log is from a high performance 4 cylinder turbocharged Time Attack engine.  The strat mode uses a combination of throttle reduction and retard to achieve the desired torque limit.  The Torque target is 600Nm which is lot lower than the potential output from this engine.  The Engine Torque (Uncorrected) Nm is the torque the engine would be producing without torque reductions being applied.  The Engine Torque (Nm) is the ECU calculated output.  In this case, given the strat mode heavily favours throttle control of the torque limit, the margin to the Uncorrected Torque is quite small showing the throttle is controlling the bulk of the airflow through the engine.  The retard component makes up balance to meet the torque target of 600Nm.  The ECU will constantly correct the throttle area demanded and the ignition angle to achieve the 600Nm torque target.  Such example shows an extremely smooth output delivery of 600Nm is being applied.    

Screenshot 3: Example Logging Data


There are many ways the ECU can be used to limit the torque in engine.  Stay tuned for another post where we discuss the “Engine Torque Limit Strategy” section.



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