The Low-Z extension board provides faster injector switchoff and obsoletes powerflyback for new installs. Please see GenBoard/Manual/Flyback

This page is obsolete ! Only useful when verifying old installs.


See [powerflyback item in webshop]. Note: not available any longer !

GenBoard features a powerful GenBoard/Manual/Config/InjectorOpening model that makes it possible (or in some cases just easier) to tune with high-flow injectors. We call injectors high-flow when the injector flowrate in cc/min is close or higher than the cylinder displacement (in cc). Like 550cc/min injectors for 450 cc cylinders. This is common for high-power (high-RPM or high boost or both) engines. We've seen giant 1600cc/min injectors for 550cc cylinders.

The injector pulsewidth at idle and low-load can be very short, in the 600..1200 usec range. In this range, the injector-opening characteristic parameters are sensitive to good tuning. Alternative to the injector-opening parameters, almost as good effect can be reached with many-many load-bins, and much work (and strange shape VE table at very low load), but this is a very bad workaround: only makes sense to apply this method with alien ECM that has primitive injector-opening model.

Raising the flyback voltage makes the injectors close faster. This makes tuning easier. This is what the power-flyback does.

In the worst case, if injectors in the set have different opening characteristics, (this can happen, even the flowrate was measured to match perfectly at fully opened state ! often seen with Siemens injectors, but happens elsewhere too), it might happen that only very rich idle is possible (engine stumbles as you try to achieve a not-so-rich idle): pulsewidth must be tuned for the injectors with slowest opening or faster closing : naturally results in overly rich condition for injectors with faster opening or slower closing.

It's not easy to see the addon-board because of the same color. It's at the bottom of the picture, has 72 components (36 on top and 36 the bottom side): the ultra-fast black power-diodes are horizontal on the picture.


Power-flyback mounted on v3.x (actually v3.3):

This addon board is used instead of the "traditional" direct (min 0.61mm2) wire between same pads.

The same board can also be used outside the ECM Alubos case (beware of the "connection polarity"):



No disadvantage at all when PWM-ing is not configured.

As a side-effect, if PWM-ing is used, PWM duty% must be slightly raised (say, from 30% to 35%). Tiny bit higher current consumption. Very good trade for the gains (easier tuning, smooth running, better engine economy).

See also