rusefi.com

Hi all,

Decided to make a new topic as this is a total different issue/question then the intential topic.

Ive been wiring the MicroRusefi on a Engine test bench for a school. Pretty much everything is working now. They wanted the Fiat 500 Twinair engine on there. They did some research as it uses a multiair system. This means they "manipulate" the inlet valve actuation with a solenoid. They didnt want to use that strategy and just have it working at full lift all the time. They made the assumption that without any power to the solenoid it would turn to full lift mode.

We now know that is not the case. Its actually opening the oil supply to the valve actuator fully so no lift occurs.
The solenoid controlling the system is like 0.5 ohm. In order to stop it from turning into a ball of red copper wire they use a peak and hold control.
After the inlet lobe is passed, they will disengage the solenoid to help it fill the circuit and make sure there is no air in there.

I tried manually putting the valve into full lift position, but then it wont bleed properly and could cause issues on the long run.

So im guessing i have 2 choices. Either find a way to make it mechanical, or use the electronics as they are meant.

So the question is, would this be something that could be controlled by Rusefi? Or would it be best to create a second trigger wheel with a small controller that would then actuate the solenoids at the right time and have some circuit that would do the peak and hold without a external control?

thanks

https://www.shop.rusefi.com/shop/p/gdi4 is technically a peak-and-hold but probably an overkill

https://github.com/rusefi/hw_legacy/tree/master/Low-Z_LM1949 was never populated/finished/tested

For driving the solenoid you have several solutions simpler than peak n hold. You can use a resistor in series like we do on low Z injectors. It would slow the response of the solenoid but you don't really care since you want it to be always active after power on.
You could use a small switching regulator with current limit to supply current to the solenoid. Same result but more elegant.
With both of these solutions you will need a GPWM table set up to keep the valve open at start up below a set rpm in order to bleed the system.
The ideal solution would be a Lua script to PWM it like it was intended. In the script you can have a mode that bleeds the air from the circuit at start up by leaving the valve partially open for the amount of time you want.

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