Automatic flyback board for LowZ (low impedance) injectors.
Although this supports injector PWM-ing on 8 channels (so any injector output can be used), when using only 4 channels (to stay compatible with the 4-channel version), please use these 4 channels: inj-A,B,C,D (1,2,3,4): EC36/7, EC36/19, EC36/8, EC36/20 respectively.
Genboard v3.x supports injector PWM-ing:
After about 1msec of full (14V) drive, PWM-ing (35..50% duty is most common) is the coolest method for driving low-impedance injectors (results in less heat in injector drivers).
This automatic flyback board provides the required low voltage flyback while PWM-ing is active, and high voltage flyback to make injectors turn off faster after PWM-ing is over (for the best of both worlds).
Effectively, instead of low-voltage flyback all the time this results in faster injector switchoff and therefore more predictable fuel-delivery between cycles and between different injectors (different injectors have slightly different closing characteristics, even from the very same manufacturing batch - even if measured+grouped, injector closing characteristics changes a bit during operation).
If PWM-ing is not required, the default 30V "high voltage flyback" is a cheaper solution with same effect (but than PWM-ing must be disabled to avoid damage).
Installation on v3.7 is easy, just 8+1 connections:
- Don't install the 30V transient diode on the mainboard (remove it, if installing on an assembled ECU)
- The DPAK FETs should be on top, as on the picture. Connect the 8 pads to their matching throughole pads on the v3.7 (or newer version) mainboard right under. (on v3.6 and earlier those pads do not exist, and although electrically OK to connect to the injector outputs, difficult to solder mechanically perfectly and therefore not recommended).
- The AF8 PCB corner pad goes nowhere
- On the AF8 PCB: 2 pads left, they are (also called "DPAK PFET Drain, shared") internally connected: verify with DVM (measure 0 Ohm between them). Connect one (practically the closer pad) to EC36/23 flyback connection with 0.75 mm2 wire (note: through the harness, this is connected to injector shared+ ).