Air Injection Control Valve: Description and Operation
GF14.30-P-2020MIR Component Description Of Air Pump Switchover Valve
ENGINE 272.949 in MODEL 230.454 as of Model Year 09 /Modification Year 08 model refinement package
ENGINE 272.968 in MODEL 230.458 as of Model Year 09 /Modification Year 08 model refinement package
ENGINE 273.965 in MODEL 230.471 as of Model Year 09 /Modification Year 08 model refinement package
View of the engine from the front right
128 Check valve (vacuum)
M33 Electric air pump
Y32 Air pump switchover valve
Location
The switchover valve is located in front of the RH cylinder head.
Task
For the air injection, the switchover valve actuates the air shutoff valves with vacuum from the intake manifold.
Design
1 Aeration connection
2 Vacuum pressure supply connection
3 Connection to the air shutoff valves
a Armature disk
b Return spring
c Housing
d Solenoid
e Electrical connection
f Rubber seal
Function
1 Ventilation connection (atmospheric)
2 Vacuum supply connection (from intake manifold)
3 Connection to the air shutoff valves
4 Electrical connection
A Air pump switchover valve energized (vacuum applied to the air shutoff valve)
B Air pump switchover valve deenergized (air shutoff valve ventilated)
The switchover valve is actuated directly for a released air injection by the ME-SFI [ME] control unit (N3/10) by means of a ground signal.
The voltage supply takes place from "circuit 87 M2".
When energized, the armature disk (a) is drawn by the solenoid (d) and the rubber seal (f) closes off connection 1. The connection between connections 2 and 3 is opened and the vacuum from the intake manifold builds up in the air shutoff valves.
In the deenergized state, the connection is restored between connections 1 and 3, which causes the air shutoff valves to be ventilated again (through connection 3).
A check valve (128) ensures that the vacuum develops or remains in the vacuum switchover valve. Thus actuation of the air shutoff valves by means of vacuum is guaranteed under all operating conditions.