Introduction Of The New A-Class, Model Series 176 B - Mercedes-Benz Series 176 Introduction Into Service Manual

CAMTRONIC M 270 DEH16 LA
The M 270 DEH16 LA engine in combination with
the 6-speed manual transmission is equipped with
CAMTRONIC valve lift adjustment.
The intake camshaft valve lift adjustment actuator
is located on the cylinder head cover next to the oil
filler neck.
The intake camshaft valve lift adjustment actuator
actuates an axial camshaft adjustment on the
intake camshaft, whereby a switch is made
between the large and small cam lifts. The
switchover of the camshaft to a smaller lift closes
the intake valves sooner. This leads to optimization
of the gas exchange under partial-load conditions.
CAMTRONIC valve lift adjustment
1 Tappet
2 Curved tracks
Y49/8 Intake camshaft valve lift adjustment
actuator
Y49/8b1 Intake camshaft valve lift adjustment Hall
sensor
– This printout will not be recorded by the update service. Status: 06 / 2012 –
Description of engine M 270
The actuator is actuated by map control in a speed
range from 1000 rpm to 4000 rpm by the ME-SFI
[ME] control unit using a pulse width modulated
signal (PWM signal) of 1 kHz.
In the starting position both tappets are retracted.
The engine starts when the intake valves switch to
large lift.
The initial switch to small lift ensues once the warm-
up phase is finished. When the ME-SFI [ME] control
unit actuates the actuator the coil in the actuator is
energized and one of the two tappets moves to the
curved track. The shape of the curved track
generate an axial displacement of the camshaft and
a switch to a smaller cam lift. The tappet is returned
mechanically by an incline in the curved track.
The camshaft is returned by energizing the coil
again. The other tappet is then extended and the
camshaft shifted in the opposite direction to the
position of the cam with the large lift.
P05.20-2378-00
Introduction of the New A-Class, Model Series 176 b 39