M50 Vanos activation/deactivation rpms

[Thomas525]

Hi have searched and I can't find this information on many threads and on goggle. Never clearly stated. Even the Bentley manual does not say. Does anyone know when the single vanos on an M50 activates, and deactivates and reactivates etc. At which rpm. Thank you. Thomas

[Adrian Btz]

Curious too

[shogun]

it depends on various factors:

BASIC FUNCTION OF BMW VANOS SYSTEMS
All BMW VANOS systems are operated through electric/hydraulic/mechanical control.
Electric Control: The engine control module is responsible for activating a VANOS solenoid valve based on DME program mapping. The activation parameters are influenced by the following input signals:
• Engine speed
• Load (intake air mass)
• Engine temperature
• Camshaft position
• Oil temperature (MS 42.0 only)
Depending on the specific VANOS system, the solenoid valve is one of two types: • Basic black/white (on/off) solenoid valve. Found on M50 TU and M52 engines. • Variable position solenoid valve. Found on the M52 TU and M62 TU engines.
Hydraulic Control: The position of the solenoid valve directs the hydraulic flow of engine oil. The controlled oil flow acts on the mechanical components of VANOS system to position the camshaft.
Mechanical Control: The mechanical components of all VANOS systems operate under the same principle. The controlled hydraulic engine oil flow is directed through advance or retard activation oil ports. Each port exits into a sealed chamber on the opposite sides
of a control piston.
• The control piston on six cylinder engine systems (M50TU, M52 & M52TU) is connected to a separate helical gear cup. • The control piston on the M62TU VANOS system incorporates the helical gear.
In its default position the oil flow is directed to the rear surface of the piston. This pulls the helical gear forward and maintains the retarded valve timing position. When the oil flow is directed to the front surface of the piston, the oil pushes the helical
gear in the opposite direction which rotates the matched helical gearing connected to the camshaft.
The angled teeth of the helical gears cause the pushing movement to be converted into a rotational movement. The rotational movement is added to the turning of the camshaft providing the variable camshaft positioning.
https://www.meeknet.co.uk/E38/m62tu.pdf

added comment by ed323i from the E36 forum:

The point is that there are no "fixed" rpms for Vanos to enable. It depends on the temperature, load (how much air is the engine sucking) and the RPM, and, under heavy throttle also depends on vehicle speed. Oh, I forgot, it also depends on if you have a manual or auto transmission. So, quite complex.

In general, with a warmed up engine (85+ degrees C coolant) and manual transmission, and light throttle: it should turn on between 1250 and 5200 rpm.
With heavy throttle, it will disable at 4000 rpm if you're driving very slowly (+/- 10 kph), and at 4992 rpm if you're driving at 120 kph or higher. This probably is to prevent giving you too much torque at lower speeds/gears (wheel spin, safety measure).

And now I'm still leaving out some variables. But you get the feeling.
M50TU and M52 Vanos is 100% identical, mechanically-speaking, but the rpms at which it enables and disables are probably slightly different due to different flow/torque characteristics.

https://www.bimmerforums.com/forum/showthread.php?2396862-M50-Vanos-activation-deactivation-rpms