Diesel ECU Torque Limiters – A Brief Explanation

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We get many questions asked of us concerning torque limits and how they differ between M/T and A/T vehicles. So I’ll give a brief explanation. Its pretty important as modifying the amount of torque the ECU allows the engine to produce is what you feel when you get your vehicle¬†tuned.

There seems to be a bit of “smoke and mirrors” happening around torque limit settings and how they are modified when we tune the vehicle. Some tuners don’t like to show or explain their modified maps for various reasons – guarding their product, lack of knowledge or that they are slaved to someone else’s tunes and don’t have access to the maps and/or have the software and expertise to interpret or edit the maps.

The featured image depicts our modified Max Torque Limit map for the PX Ranger. The Blue line is stock, the Red line is the modified limit. This particular map in stock trim is identical for both manual and auto applications. As it is across the engines entire RPM range it effects the first three gears in the manual – and the last three also!
There are however 3 other torque limiting maps in the stock tunefile (out of 180 potential maps) which differ slightly between the manual and auto PX’s. We don’t modify these ones for many reasons, none which are of any interest to performance or drive-ability improvement.
So to summarise, we keep the limiters, we just edit them to allow more torque to be made by the engine thus transmitting this torque through the drive line – within safe limits.

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