Double VANOS Operation

Double VANOS Operation


The MS42.0 engine control module (ECM) controls the operation of the Double VANOS system. The base setting of the camshafts with the engine off:
- Intake cam - retarded
- Exhaust cam - advanced

This is also the "fail safe" position in the event of an electronic control failure. Both camshafts are held in these positions by oil pressure from the engine oil pump. The exhaust camshaft is held additionally by a spring in the VANOS actuator.

When the engine is started, the camshafts will remain in these positions until the ECM detects the positions of the camshafts from the camshaft sensors (approximately 50 revolutions or 2 - 5 seconds).

Once the cam positions are recognized, the ECM will make an initial cam timing adjustment based on RPM and throttle position. Following this initial setting, the intake air and engine coolant temperature are used to adjust the timing.

When the ECM detects that the cams are in the desired position, the solenoids are modulated (100 - 220 Hz) maintaining oil pressure on both sides of the actuators to maintain the camshaft timing.