Secondary air injection system 960

Применимость

Air PumpSolenoid valvePulsed secondary air injection system (PAIR) pump relayMotronic 1.8 control moduleAir injection ductsCheck valveShut-off valveThe B6304S for USA/Canada and all F versions of the B6254S are fitted with an secondary air injection system and EGR system in order to meet the latest exhaust emission requirements. The secondary air injection system functions essentially as for 5 cylinder engines.

Reduces HC and CO values

The secondary air injection system supplies air to the exhaust gas ports during the engine warm up phase in order to initiate an "afterburning" of hydrocarbons (HC) and carbon monoxide (CO). This "afterburning" in the exhaust manifold reduces the time the catalytic converter takes to reach operating temperature. When the air pump is switched on the timing is retarded more than normal to raise the temperature in the manifold.

Main components

Motronic 1.8 control module. Switches the pulsed secondary air injection system (PAIR) pump relay on and off based on coolant temperature information at the moment of starting.Air injection system pump relayin the relay and fuse box in the engine compartment. The relay takes care of the power supply to the pulsed secondary air injection system (PAIR) pump and the solenoid valve.The air pumpis mounted on a bracket by the front right side member. It has a powerful electric motor that pressurizes the air and impels it into the system.The solenoid valveis connected to the engine inlet manifold and is mounted on a bracket next to the relay and fuse box. When the solenoid valve is activated the vacuum in the intake manifold is drawn to the shut off valve, which opens.The shut-off valveis needed when the system is switched off. It prevents air from being drawn into the exhaust ports via the pump.The check valveis on the right of the engine on the pipe to the cylinder head. Together with the shut-off valve it prevents exhaust gas from reaching the pump.The air injection ductsin the cylinder head supply air to the exhaust ports.

ACTIVATION

The pulsed secondary air injection system (PAIR) pump is switched on during cold starting immediately after the engine starts and normally runs for around fifty seconds.

Extended on-board diagnostic (OBD) system

The diagnostic trouble codes (DTCs) for the EGR system are added to test mode 1. In test mode 3 the EGR vacuum controller and the secondary air system are activated at the start of the cycle. In addition at the end of test mode 3 a simulated engine speed (RPM) signal of 1,500 rpm is added so that it is possible to quickly check the rev counter in the combined instrument.