ME tumble flap switchover function - GF07.61-P-4017V

ENGINE 272.942 in MODEL 171 

ENGINE 272.963 in MODEL 171 

Fig 1: ME Tumble Flap Switchover Function (Shown On Engine 272)

Courtesy of MERCEDES-BENZ USA

Shown on ENGINE 272 

At partial load, tumble flaps can be fully swung out in each cylinder intake port in the intake manifold. This closes the intake manifold by around 50%. The flow speed of the intake air is increased and allows for improved distribution of the fuel/air mixture in the combustion chamber.

The tumble flaps are moved via an aneroid capsule and a rod to the flap shafts.

The intake manifold tumble flap switchover valve is integrated in the vacuum line to the aneroid capsule. If it is de-energized, the aneroid capsule is ventilated and the tumble flaps are lowered in the intake duct (closed position).

If the intake manifold tumble flap switchover valve is actuated by a ground signal from the ME control unit, vacuum pressure from the intake manifold enters the aneroid capsules. The tumble flaps turn in the intake duct.

Actuation is enabled under the following conditions:

• Engine speed less than about 3000 rpm (e.g. engine 272.963)
• in neutral for variants VC5 and VC6 (on neutral locked from variants VC7)
• Engine load less than approx. 30%.
• Coolant temperature greater than 60°C

Read out the variants using STAR DIAGNOSIS under the menu item "Control unit version".

The mechanical end position of all tumble flap shafts are monitored by a position sensor. For diagnosis, following engine start, the tumble flap switchover is actuated briefly to test the actuation and achievement of the end positions.