Just found this on renlist:
"VarioCam
VarioCam, the adjustment of the intake camshafts at engine speeds of approx. 1,300 rpm* and 5,920 rpm, produces a major part of the engine output, the engine torque as well as the good exhaust values at idling speed. Engine speeds below 1,300 rpm produce a slight overlap in the valve stroke curves for the intake valves in relation to the exhaust valves.
This particularly affects low proportions of hydrocarbons (HC proportions) in the exhaust gas before the catalytic converters. If the engine exceeds the 1,300 rpm mark *, the intake camshafts are adjusted by 12.5° (by 25° if measured a the crankshaft).
Adjustment of the camshafts to produce a greater overlapping of the valve stroke curves for the intake and exhaust valves results in improved cylinder charging and thus an increase in engine torque. In the case of engine speeds above 5,920 rpm, the intake camshafts are returned to the basic control times (as for engine idling speed). If the intake valve closes later, additional amounts of intake air can be drawn in. This produces a recharging effect since the flow of air is not interrupted. This also results in improved charging of the cylinders and an increase in performance.
* The value 1,300 rpm increases to 1,480 rpm with engine oil temperatures of approx. 133°C."
"VarioCam
To increase the torque and to improve cylinder charging, the engine has two VarioCam actuators which are installed in the chain tensioners of the camshafts. The two actuators are operated by electromagnetic valves activated by the DME control unit.
Functioning
When the ignition is switched on, the electromagnetic valves of the camshaft adjusters are supplied with positive potential. If the engine is started, the control unit applies ground to terminal 25 (camshaft adjuster for cylinder line 4 - 6) and to terminal 52 (camshaft adjuster for cylinder line 1 - 3) if the following conditions are fulfilled (VarioCam activated);
1 - Engine oil temperature between -3°C and 133°C
2 - Engine speed > 1,300 rpm
3 - Throttle opening > 5%
or
1 - Engine oil temperature > 133°C
2 - Engine speed > 1,480 rpm
3 - Throttle opening > 3.9%
The ground potential is deactivated by the DME control unit (VarioCam deactivated) if:
Engine speed > 5,120 rpm"
