Air Injection: Description and Operation

GF14.30-P-3012AM Air Injection, Function
ENGINE 113.990 in MODEL 211, 219
ENGINE 113.991 in MODEL 215, 220
ENGINE 113.992 in MODEL 230 up to Model Year 2008
ENGINE 113.993 in MODEL 463 up to 31.5.12
ENGINE 113.995 in MODEL 230 up to Model Year 2008





126/1 Left air shutoff valve
126/2 Right air shutoff valve
128 Vacuum check valve

B11/4 Coolant temperature sensor
B17/8 Charge air temperature sensor
B28 Pressure sensor (charge air)
B37 Accelerator pedal sensor
K17 Air injection relay (models 211, 219)

K40/4kN Air pump relay (model 230 up to 06/2002)
K40/4kO Air pump relay (model 230 from 07/2002)
K40/7kN Air pump replay (model 215, 220)

L5 Crankshaft position sensor
M16/6 Throttle valve actuator
M33 Electric air pump
N3/10 ME control unit

N10/1kO Secondary air pump relay (model 463)
Y32 Air pump switchover valve
Y62 Fuel injection valves

The air injection more rapidly warms up the catalytic converters to operating temperature after starting and thus improves the exhaust emission values in the warming-up phase.

The injected air is prepared by the electric air pump with released air injection. The electric air pump is actuated by the ME-SFI [ME] control unit via the following relays:





The air pump switchover valve is actuated simultaneously by the ME control unit at the ground end.

a Vacuum supply from intake manifold
b Injected air from air pump
c Injected air to cylinder head

The air injection is actuated for maximum 150 seconds after engine start, if:

^ Coolant temperature > -10°C and less than 60°C
^ Engine speed <3000 rpm
^ Throttle valve is not fully open (no full-load range)

Function
The air pump switchover valve switches the intake manifold vacuum (a) through to the aspirator shutoff valves (126/1, 126/2) on the left and right. These open and the injected air (b) from the electric air pump is blown into the exhaust ducts of the cylinder heads (c).

The injected air reacts with the hot exhaust gases in the outlet ducts. An oxidation of carbon monoxide (CO) and hydrocarbon (HC) takes place (afterburning).
This afterburning (exothermic reaction) leads to a further increase in the exhaust gas temperature, which additionally heats the catalytic converters.