How to control the HFS-4 from a Link G4+ ECU

[MethoD]

I would like to connect my HFS-4 to my Link G4+ ECU in such a way that I can control the signal (and flow) of the water/meth injection independent from the fuel injector DC.

The Link ECU has general purpose Aux outputs that can deliver a PWM signal with variable duty cycle. I can assign the DC based on a 3D table with RPM and MAP as X and Y axis.

What I am not sure of is how to wire the HFS to the Link ECU.

The HFS has wires for both "conventional" injectors and "peak and hold" injectors. I don't know which set of wires to connect to the ECU.

Also, I am unsure of how to connect the wires to the ECU. Would the (+) go to a switched 12v from the ECU and the (-) go to the Aux? Or would the (-) go to ground and the (+) go to the Aux output? I think the Aux can be configured for either type of switching.

Thanks in advance
MethOD

[Richard L]

You just need to send the PWM signal to the green wire of the grey harness. No need to use the green harness. Set the THRES to minimum (fully CCW).

Ideal PWM frequency: ~30Hz.

The red wire goes to a switched 12V source, active at the pre-crank or run key position.

[MethoD]

Thanks for the information -- I believe that's just what I needed!