After checking the VSV for proper operation and confirming the Air Pump actually pumps air, it’s time to dig into the engine to test the valves and clear the Air passages if possible.
Removing a few choice components on the Porsche 911 makes access to the divert-er or “Dump” valve and check valve possible. Porsche uses a vacuum reservoir to help vacuum operated function during low engine vacuum conditions. It is mounted on a fixture which bolts over the air passages we are looking for.
Ahhhh! there it is. The very dangerous and highly elusive Dump valve. I think I’ll make it mad.
The larger threaded hole is where the check valve attaches to the fixture and the more silver colored smaller threaded hole is for the air line that feeds the right cylinder head.
The check valve will be replaced even though it still passes air. More importantly shop air will be forced through the air passages in an attempt to open them so the Air can reach the exhaust side of the cylinder heads.
So we’ll blast out the passage ways, reassemble and test the Secondary Air injection. Manually starting the pump we got an acceptable voltage change in the O2 sensors. After two drive cycles the On Board Diagnostics, checked off the Secondary Air Injection as functioning properly. It’s now OK to turn the car back to the customer with the cravate that we can not know how clean the passageways are. They are not likely to improve but are passing enough air at this time to satisfy EPA standards as programmed into DME and monitored by OBD II