Secondary air injection function

P14.30-0232-06

60 Air pump
62 Air cleaner
126 Left air shutoff valve
126a Right air shutoff valve
127 Check valve (injected air)
K17 Secondary air injection relay
N3/12 Right ME-SFI control module
Y32 Air pump switchover valve
Y33 Air pump electromagnetic coupling
a Air admission

Secondary air injection ensures that the catalytic converter heats up more rapidly to its operating temperature and thus improves the emission levels during the warming-up phase.

Function

The air pump switchover valve (Y32) and the electromagnetic clutch of the air pump (60) are actuated simultaneously by the ME-SFI control module (N3/12) for a maximum of 150 seconds after engine start if:

- coolant temperature > 10 °C and < 60 °C

- engine speed < 2000 rpm

- throttle valve not fully open

- after actuation, secondary air injection remains deactivated until the coolant temperature is greater than about + 60 °C and then drops to below 40 °C.

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Actuation of the air pump electromagnetic coupling (Y33) creates a positive connection to the belt pulley driven by the poly V-belt. The air pump (vane cell pump) is driven.

The pump draws in air through a maintenance-free filter and pumps it to the air shutoff valve.

The air pump shutoff valve switches the intake manifold pressure to the air shutoff valve (126, 126a). 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 exhaust tract. Oxidation of the carbon monoxide (CO) and hydrocarbon (HC) takes place and results in an additional increase in the exhaust temperature.

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