Caterham/Duratec; fuel pump operation?

[Austin David]

@sf4018 that's a great writeup.  Reading between the lines, it really does sound like Caterham has some magic juju burned into their ECU.  I tried to get an unlocked model from SBD for my ITB project but wasn't able to make headway, and I'm so far pretty happy with the flexibility in this ME221 unit.  Like you, I probably underestimated the effort required before starting  but I definitely know the car a lot better now than I did before...

[Austin David]

catching up: the ME221 takes a fuel pressure input, but it's not particularly prominent in the interface.  This input appears to do the right thing, when calibrated.  I put a 0-100 psi sensor on the fuel rail, along with an analog gauge, and calibrated the fuel pressure sensor.  I've got the fuel pump driver module (FPDM) working and slaved to a general purpose table, driven at 35% idle, which corresponds to about 40 PSI, then linear up to 100%.  That table's input is injector duty, which I figure is the most linear guess about fuel pressure demand.   I assume there will be some tuning required, I doubt to see such a linear relationship between FPDM duty and fuel pressure.

[CatManDo]

For what it's worth, we talked to Caterham's chief engineer on this a while ago. They are just sending a fixed pwm signal to the pump controller from the ECU to run the pump. It does not use any pressure  sensor or closed loop control. The fuel pump assembly is right out of a Ford Focus. Why they even used the controller is a mystery.

 

[Austin David]

they used a controller because they're (I assume) not running the pump at full blast, AND they don't have any active pressure management.  Without more information I could only guess, but I assume the ECU is sending some sort of predictably-variable duty to the pump, like based on injector duty.  That's what I'm doing, but I also have some amount of pressure feedback and monitoring.