Secondary Air Injection (AIR) System, Checking

Secondary Air Injection (AIR) System, Checking







The Secondary Air Injection (AIR) system causes the catalytic converter to heat up more quickly, resulting in earlier operating readiness following a cold start.

Principle
Due to over-enrichment of the mixture during the cold start phase, there is an increased amount of carbon monoxide in the exhaust. Secondary Air Injection (AIR) improves secondary oxidation in the catalytic converter and therefore reduces emissions. The heat produced by secondary oxidation greatly reduces start-up time for the catalytic converter, therefore improving exhaust quality during the cold start phase significantly.

Function
- In the cold start phase, the ECM -2- activates the secondary air pump -12- via the relay for secondary air pump -1-. Air reaches the combination valve for Secondary Air Injection (AIR) -10-.
- The Secondary Air Injection (AIR) solenoid valve -3- is activated in parallel, which allows the vacuum to reach the combination valve for Secondary Air Injection (AIR) -10- and the vacuum diaphragm for boost pressure regulation -7-. The combination valve for Secondary Air Injection (AIR) thereby opens the path for secondary air to the exhaust channels of the cylinder head.
- To prevent unnecessary torque losses, secondary air is routed to the turbine wheel of the turbocharger -8- so that air can get directly into the catalytic converter. For this, the boost pressure regulation pressure unit opens the boost pressure valve -7-. The pressure unit, designed as a double reservoir, has a vacuum connection for this on the intake side.

1 - Secondary Air Injection (AIR) pump relay -J299-
2 - Motronic Engine Control Module (ECM) -J220-
3 - Secondary Air Injection (AIR) solenoid valve -N112-
4 - Intake manifold
5 - Check valve
- Installed position (light/dark side): Arrow points in direction of flow, as shown in figure.
6 - Vacuum reservoir
7 - Vacuum diaphragm for boost pressure regulation
8 - Turbocharger
9 - Cylinder head
10 - Combination valve for Secondary Air Injection (AIR)
11 - Air filter
12 - Secondary Air Injection (AIR) pump motor -V101-