GF07.10-P-1018MI Tumble Flap Switchover, Function

GF07.10-P-1018MI Tumble Flap Switchover, Function

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)

Tumble flap switchover function sequence
For the tumble flap switchover, the ME-SFI [ME] control unit uses a ground signal to actuate the intake manifold 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 intake manifold tumble flap 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 deenergized state, the vacuum unit is ventilated by the intake manifold 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 via 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.

Component Identification: