Vanos - BMW 1999-2005 M3 Service Manual

Camshaft Timing Chain
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Vanos

The main components of the double
VANOS system are:
Intake and exhaust camshafts with
helical spline inserts
Camshaft sprockets with
adjustable gears
VANOS actuators (two position
piston housing with
internal/external helical spline
cup)
Three-way solenoid switching
valves
Camshaft position impulse wheels
Hall effect camshaft position
sensors
Camshaft position is varied based on
engine rpm, throttle position signal,
intake air and coolant temperature.
When engine is started, camshafts are
in deactivated position:
Intake camshaft is held in
RETARDED position by oil
pressure.
Exhaust camshaft is held in
ADVANCED position by preload
spring and oil pressure.
Within 2 - 5 seconds (50 engine
revolutions), the ECM begins
monitoring and controlling camshaft
117-5
2/25/2009 9:52 PM