Recommended flyback for GenBoard/VerThree: DD flyback

See the new trend, the GenBoard/Manual/PowerFlyback

[Rob's flyback page] - similar content, more pictures

In ancient times, the

Since the precise injector opening is configurable (this is a nice feature that not many ECMs have, and no other opensource ECM) usually the low voltage flyback is used also for highZ injectors. In the worst case, there is some adjustment needed (see GenBoard/Manual/Config/InjectorOpening) to smoothen idle if the injector opening parameters were guessed badly originally.

depending on the type of transient suppression diode used (the 6V8 and 20V are our common values of 0.6kW UNIDIR 1SMB20AT3 ONSemi SMB diode, there are other types of course)




Recommended low voltage flyback:



Increasing injector flyback voltage with external diode(s)

If - with a very powerful engine, big injectors - you cannot get a good idle as lean as you like (say it idles OK at lambda=0.8 but not at 1.0), chances are good that the injectors have different injector-opening characteristics (this is possible, even if the flow is equal to great precision when injectors are fully open). We had a case with a set of Siemens injectors. The low voltage flyback does not hide any such differences between injector-opening characteristics.

The easiest way to increase flyback voltage is with a high-current, 2..4V diode: 3..5 BY399 diodes and a 0.1Ohm 5W resistor in series.

Use 2 of these (N x diodes and 0.1 Ohm resistor) in parallel.

If you do this, remove D100 ("PJ52 LM" SMB diode among the 16 flyback ES2J diodes) from the board (that provides some protection from forgotten flyback when PWM-ing is not applied; but prevents raising the flyback rail above 18V).

[picture of proposed external mod]

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