tratto da twin power:

The Triumph twins use narrow band Lambda sensors to monitor the AFR (air/fuel ratio). Their job is to sniff the exhaust gas and report the AFR to the ECM. The ECM will then trim the injector pulse width so operation is kept at 14.7:1 AFR under idle, light acceleration, and slow cruise conditions. This is known as “closed-loop” operation. Under heavier acceleration or wide-open throttle the ECM ignores the O2 sensors as the engine requires an AFR richer than 14.7:1 for power, which is outside the design parameters of the narrow band sensor. This is known as “open-loop” operation.

Triumph twins use “closed loop” operation at small throttle positions, this enables Triumph to get the EFI air cooled twins through the strict manufacturers exhaust emission testing. In real life riding situations, this can make the throttle control at smaller positions awkward and many owners describe it as rough and snatchy.

Triumph Twin Power disables the O2 sensors electronically in all our performance tunes. With the sensors removed and adjustments made to the AFR table, the ECM runs in “open loop” operation and takes its fuelling information from the fuel maps embedded in its memory. We found that by disabling the O2 sensors, we can programme much smoother throttle control using the fuel tables.