I’m running a return-less fuel system with a fuel pump controlled by an ECUMaster Dual H-bridge. EMU Pro sends duty cycle messages (B1 B2 B3 B4 PWM1 PWM2) to the H-bridge and it is responding correctly by varying the duty cycle as requested.
Now I want to be able to do this in closed loop where the EMU varies the duty cycle to hit a programmed pressure. I see that firmware version 230 has new support for GM’s Alpha fuel pump module… can I get to that CAN stream and modify it to talk to my H-bridge? Or is there another method I should be using?
Maybe something like this. You can assign an aux out that’s not in use, then use the PID controller for standard PWM pump. From there send over CAN the DC from the pump control. Let the ECU do the control and just send the DC to the HBridge. I think you may need to convert DC to raw or a conversion table to scale 0-100 dc as 0-255. I may be wrong.
Ah, yes. Very clever! The values the H-Bridge expects vary from 1 to 4905, so a simple multiplication of duty cycle * 49 yields the right value to send to the H-Bridge.
Yes, that works great. Many thanks!
edit: seems I’m late but same answer
Have you looked at setting the output to an H-bridge and setting the mode to PWM closed loop?
You could base the duty cycle on engine load and fuel pressure target on what feature your basing the fuel pressure need on. The fuel pressure target can be set using a 3d table like most other target tables can.
I reserved H-bridge 3 for fuel pump control, but was concerned that it might need more power than what the Pro could provide. Nor could I double Pro bridges since I’m using 2 for engine control. So (based on advice from this forum) I used an ECUMaster dual H-bridge to drive the pump, and then use the Pro to drive the (external) H-bridge. The vehicle starts up and idles fine. I’ve got a nice looking stable 50bar HP pump, and a reasonably stable 500kPa low pressure pump. I’ll fiddle with the PID controls a bit to calm it down, but this is working well.
