See
Normally variable timing (VVTI or Vanos) solenoids are powered by constant +12V on one pin and controlled by low-side outputs as sane engineering practice applied generally. (For example BMW M50 Vanos is sane).
In VEMS ECUs there are plenty N-FET type low-side driver outputs anyway, eg. free injector output or IGBT ignoutput, the ECU switches GND as usual), so the extra NFET-outputs are optional (useful if 8 cylinders consume many outputs, or other special relays or actuators are planned to be connected).
Some Vanos solenoids require Hi-side PFET outputs
- Hi-side PFET outputs: 2 or 4
If the Vanos solenoid is driven by high-side output
- if the ECU switched +12V (perhaps the BMW engineers lost their medicines those days),
- and accordingly: the direction of flyback diode molded in the VANOS solenoid connector is connected with common anode to GND
- which is not easily changed; measure this diode to verify the drive polarity
- such as most S54B32 (iirc S50 also), then Hi-side P-FET outputs are recommended.
So please check the Vanos solenoids and measure diode polarity (and determine power direction)
- and never forget to mention the exact engine model.
BMW usually requires 2 outputs per Vanos solenoid. See [camshaft angle control in VemsTune help]