ME-SFI tumble flap switchover function - GF07.61-P-4017MIS

ENGINE 272.9 (except 272.974) in MODEL 221.0 /1 (except 221.095 /195) as of model year 2009/AEJ 08

ENGINE 273.9 in MODEL 221.0 /1, 216.3 as of model year 2009/AEJ 08

View of variable intake manifold from left front

Fig 1: Identifying Variable Intake Manifold Tumble Flab Switchover Valve

Courtesy of MERCEDES-BENZ USA

Function requirements for tumble flap switchover, general points

Circuit 87M ON (engine control ON)
Engine running
No idling

Tumble flap switchover, general points

In the variable intake manifold, the tumble flaps in each intake port can be swiveled inward. They can thus reduce the cross-section of the related intake port by about 50%.

The flow rate of the intake air increases and ensures better distribution of the fuel air mixture in the combustion chamber. The ME-SFI [ME] control unit (N3/10) actuates the intake manifold switchover according to the signals from the following sensors:

Hot film MAF sensor (B2/5), engine load
Coolant temperature sensor ()B11/4
Crankshaft Hall sensor (B70), engine speed
LH and RH intake manifold tumble flap position sensors (B28/9, B28/10)

Function sequence for tumble flap switchover

For the tumble flap switchover, the ME-SFI [ME] control unit uses a ground signal to actuate the tumble flap switchover valve (Y22/9), depending on engine load, coolant temperature and engine speed. The tumble flaps are swiveled inward in the following conditions:

Engine load < 30%
Engine speed <3000 RPM
Coolant temperature > 60°C

The tumble flaps are actuated by a vacuum unit. When the switchover valve is actuated, the vacuum unit is charged with vacuum from the vacuum reservoir. This causes the tumble flaps into the intake ports.

In the de-energized state, the vacuum unit is ventilated by the tumble flap switchover valve, and the tumble flaps are swiveled outward by spring force.

The mechanical end positions of the tumble flap spindles are monitored by the ME-SFI [ME] control unit through the LH and RH tumble flap position sensors.

For diagnosis, following an engine start, the tumble flap switchover is actuated briefly to test the actuation and achievement of the end positions.

	Electrical function schematic for tumble flap switchover	Model 216		PE07.61-P-2785-97CAB
	Component description for ME-SFI [ME] control unit	N3/10	Engine 273	GF07.61-P-6000MLS