Secondary air injection function - GF14.30-P-3012GS
ENGINE 111.951 /952 /955 /956 /957 /958 /982 /983 with CODE (925) low emission EURO3
ENGINE 111.983 with CODE (494a) USA version
Illustration shows naturally-aspirated engine
Secondary air injection warms up the catalytic converter more rapidly to its operating temperature and thus improves the emission levels in the warming-up phase.
The electric air pump (M33) is actuated through the air pump relay (K40/4k3) (model 202), or through the front SAM control module with fuse and relay module, secondary air injection relay (N10/1kO) (model 203)
The current consumption of the electric air pump (M33) is as much as 35 A.
Secondary air injection relay and air pump switchover valve (Y32) are actuated simultaneously by the engine control module for up to 150 seconds after engine start if:
- coolant temperature > 10°C and < 60°C
- engine speed < 3000 rpm
- throttle valve not fully opened
- After actuation, the secondary air injection remains inhibited until the coolant temperature is greater than approx. + 60°C and then drops to below 40°C
The pump draws in air through a maintenance-free filter and pumps it to the air shutoff valve. The valve at the same time prevents the exhaust gases from flowing back to the air pump (check valve discontinued).
The air pump switchover valve switches the intake manifold pressure through to the air shutoff valve (126). This opens and the air supplied by the air pump is forced into the exhaust manifold.
The injected air reacts with hot exhaust gases in the outlet port. An oxidation of carbon monoxide (CO) and hydrocarbon (HC) takes place and results in an additional increase in the exhaust temperature.
Engines fitted with supercharger
The injected air is drawn off on the pressure side downstream of the compressor. No air pump is required.
| ME-SFI control module position / task / design / function | GF07.61-P-5000GS | ||
| Air pump position/task/design/function | GF14.30-P-3100F | ||
| Supercharger position/task/design/function | GF09.50-P-3102G | ||
| Crankshaft position sensor position/task/ design/function | GF07.04-P-4116F | ||
| Coolant temperature sensor position/task/ design/function | GF07.04-P-5026G | ||
| Air shutoff valve position/task/function | GF14.30-P-4028F | ||
| Check valve (injected air) position/task/design/ function | GF14.30-P-4029F | ||
| Throttle valve actuator position/task/design/ function | GF30.22-P-4101GS | ||
| Lambda control function | GF07.61-P-4022F | ||
| Air pump switchover valve position/task/ design/function | GF14.30-P-3103A | ||
| Secondary air injection relay position/task/design/function | GF14.30-P-3101F | ||
| Three-way catalytic converter position/task/ design/function | GF49.10-P-3002F |