Is there any chance to support strategy for variable valve lift? It is used on some BMW engines (called valvetronic) and on Nissan 370Z with engine VQ37VHR. The principle is somehow similar. It uses DC motor to change leverage of valve rockers to affect valve lift. Actual position is measured by linear potentiometer. In actual sw we didnt find any strategy to be able to do this control for us.
Can we expect support for this type of control any soon, or we should scratch this idea once for all?
Kind regards
U can already use this as a DBW or custom DC motor depending on the limits of the system and if a real DBW is needed.
I think in BWM engines this mostly replaces the airpathcontrol by the DBW.
You are right. Yes the BMW uses it in normal mode as fully open Throttle body and regulating air with Valvetronic, but it can always “fall back” to normal operation, workig with TB and disabling the Valvetronic… But like you mentioned, we mostly use DBW, and definitly on all modern engines equipped with this advance technic. We didnt find other way how to manipulate H-bridge in closed loop with position measured with potentiometer.
How to set it up is depending on how exactly u want to use it. But i think with a combination of DBW, custom DC motor (with PPS as x-Axis) and a Z-Axis for target position of both u have enough possibilities to do what u want.
With Z-Axis u can set a activation condition for one of both systems and freeze the other in a specific position. Then u set up a function, which determines when u want which system as main control.
There are at least two types of valvetronic used by BMW (I believe brushed DC on N52 using something like two 20-40A drivers and brushless on N20 using something like three 10-20A drivers), and the current requirements of the motor are quite high. Also the position feedback isn’t a linear potentiometer like most throttles, but instead several hall effect sensors (3 for coarse resolution and 2 more for high resolution) where you must interpret the stepping and remember the position manually.
Furthermore your tuning effectively becomes Alpha-N, as there is no MAP sensor post-valvetronic, so it looks like a motor with a throttle tuned with “baro” correction.
Most of the people I know running these motors (myself with N20, a friend with an N52, and a shop running a bunch of B46) all lock the valvetronic open and just use the included DBW instead. Much simpler, yeah I’m sure we’re losing some efficiency at part throttle but we’re all circuit racers so we try to be at 100% throttle as much as possible 
I did end up building a circuit to handle the N20 valvetronic but I still just open it 100% on startup and then leave it there. The other guys built brackets to lock it open. I do find once it’s open it stays open, at least with the N20. If closed it stays closed. But in between, you start to need VERY strong control to fight the feedback from the valvesprings (somehow the geometry of the mechanism only affects the midrange).
Those are good points.
I will also add some of my own why the variable valve lift is not common in the aftermarket world.
Newer BMWs use brushless motors for Valvetronic, and we don’t have the hardware to drive them. Therefore, we could only support older systems with brushed motors by using the external h-bridge module. We could also decode the hall position sensors directly in PRO or with the WheelSpeedToCAN module.
But that is only half of the story. To effectively use variable lift, it should be used as a throttle. The electronic throttle gets fully opened, and the accelerator position controls the lift. This would require safety systems that will revert to the electronic throttle if there is any error with the VVL system.
Considering all this, it wouldn’t be a very effective use of our resources for now.
The most feasible solution for now is to add support for the Nissan VVL. It’s possible to control the OEM VVL driver over the CAN bus. But for now, we are entirely focused on direct injection development since we will provide the most cost-effective ECU solution for those engines.
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