At the centre of torque processing sits the Torque Coordinator — a software instance that receives all incoming torque requests, ranks them by priority, and derives the final setpoint for injection, boost, and ignition timing. This coordinator typically runs in a 10 ms task (more on this in the ECU Scheduler article).
Torque request sources include: driver demand (pedal), idle speed controller, gearbox (TCU) during shifts, traction control (ASR), stability programme (ESP), A/C compressor intervention, cruise control, engine protection limiters (thermal, knock control), and external CAN requests (e.g. retarder or trailer control on trucks).
The coordinator distinguishes between two request types: minimum-select (limiting interventions — ESP, thermal, knock control remove torque) and maximum-select (demanding interventions — idle controller, cruise control request a minimum torque). Driver demand forms the base, minimum-select interventions cap from above, maximum-select interventions push from below.
The result of this selection is the Indicated Torque Setpoint — the torque value the ECU actually acts on. Only at this point does the value feed into the calculation of injection quantity, duration, and boost pressure.
Modern ECUs (especially Bosch EDC17, MD1) separate internal torque (generated by the engine, "indicated torque") from external torque (at the drivetrain output, "engine torque at crank"). The difference accounts for friction and auxiliary losses. Both values have their own limiter maps — a complete remap accounts for both.
Raising injection quantity maps without adjusting torque clearances will result in the ECU pulling the extra torque back via internal limiters. The Torque Coordinator is the gatekeeper — it must be opened first before the other maps can have their full effect.
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