Check all hoses, especially those going to/from items 3,5,8,9 in the first diagram below. See what you can find with just the engine covers off. If nothing is obvious, you may have to remove the main "Y" air distributor (make sure to disconnect everything first) to get better access to some of the below listed components. Also, consider buying a Bentley manual...
- Check fuse for secondary air injection pump
- Check vacuum hoses
- Check piping from pump to secondary air injection valve (combi valve)
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See diagram for part location numbers:
<img src="http://pictureposter.audiworld.com/80906/secondary_air_inj.jpg">
In the cold start phase, the ECM -4- activates the secondary air pump -2- via the relay for secondary air pump -3-. Air reaches the combination valves for Secondary Air Injection (AIR) -5- and -9-.
The Secondary Air Injection (AIR) valve -6- is activated in parallel, which allows the vacuum to reach the combination valves for Secondary Air Injection (AIR) -5- and -9-. The appropriate combination valve for Secondary Air Injection (AIR) thereby opens the path for secondary air to the exhaust channels of the cylinder head.
1 - Secondary Air Injection (AIR) pump relay -J299-
Removing and installing Page 26-43
Checking Page 26-51
2 - Motronic Engine Control Module (ECM) -J220-
3 - Combination valve for secondary air injection (AIR)
4 - Secondary Air Injection (AIR) solenoid valve -N112-
Installation position Fig. 1
5 - Secondary Air Injection (AIR) pump motor -V101-
Installation position Fig. 2
6 - Check valve
Installation position (light/dark side): Arrow points in direction of flow, as shown in figure.
7 - To intake manifold
8 - Combination valve for secondary air injection (AIR)
9 - Vacuum reservoir
Installation location: Under wheel housing liner in wheelhousing
The components for the Secondary Air Injection (AIR) system are located under the air distributor between the intake manifold and the plenum chamber.
See next diagram for the following info.
<img src="http://pictureposter.audiworld.com/80906/secondary_air_inj_details.1.jpg">
1 - 6 Nm
2 - Secondary Air Injection (AIR) solenoid valve -N112-
3 - 10Nm
4 - Large shim washer
For all 3 rubber bonded bushings at bracket for Secondary Air Injection (AIR) pump
5 - Combination valve, left
6 - Seal
7 - 10 Nm
8 - Secondary Air Injection (AIR) pump with air filter attached
9 - 10 Nm
10 - Seal
11 - Combination valve, right
12 - Bracket for Secondary Air Injection (AIR) pump
Bolted to rear intake manifold.
13 - 10 Nm
14 - Screw clamp
15 - Connection tube
Between Secondary Air Injection (AIR) pump and combination valves
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Let us know how it goes. Reading posts about problems is interesting, but resolution posts are better!
Have fun.