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Fixing insidious, power robbing, vacuum leaks – When one of the vacuum actuators, three on the non-Varioram and five on Varioram Cars, or any of the rubber hose connectors fail (leaks) or slips off they can cause a rather large air intake leak. Since any leak is down stream of both the mass air flow sensor & the throttle body, no good can come from this as a good size vacuum loss can cut horsepower significantly.
I checked one of the, now 19 year old, actuators by disconnecting it and sucking on the air line that feeds it, lots of air draw, no movement. Interestingly what seemed to be a rather large vacuum leak did not throw an OBD code on my car. I ordered three 993.110.462.02, and one 993.110.461.03, one for on the top passenger side of the engine, one connected to heater blower duct-work, one on the driver side underneath the Varioram intake manifold and fourth actuator on the intake manifold similar to the others but with a longer actuating arm.
A fifth actuator that can cause a power loss is located behind the Climate Control Unit (CCU) in the dash connected to a ventilation flap. The actuator is a metal can style one and looks to be rather robust. Porsche sells it as a complete vent unit but I bet, if leaking, an inexpensive metal can style actuator purchased on eBay could be MacGyvered to replace it at low cost. I tested mine by pulling the CCU clear of the dash w/o disconnecting the CCU harness then attaching a hose directly to the actuator and drew vacuum by mouth. Once a static vacuum was applied it stayed retracted so I could infer that it was not leaking. Interestingly the actuator’s arm had become detached from the vent mechanism. I replaced the missing pin with a tie wrap, probably good for at least another five years. Once reconnected to its vacuum source, I started the engine and actuated the vent flap by pressing the recirculating air button on the CCU while observing it through the dash hole. I then buttoned things up and was good-to-go, took all of ten minutes.
It is quite easy to test the actuators including the Varioram system on so-equipped cars, all the actuators and the solenoid valves that control them you will need a helper:
1. Have your helper start the engine and run it for a few moments, to build vacuum;
2. Shuts the ignition off;
3. Turns the ignition back on without starting the engine while you observe the engine;
4. Observe the three Varioram actuators on the engine going through an initial cycling, you will need a flashlight and push down on the rubber duct attached to the fan housing to observe the third actuator underneath the intake manifold;
5. With the ignition on press the air recirculate button on the Climate Control Unit (CCU);
6. Listen for the sound of the vacuum actuated recirculating air flap moving behind the the dash;
7. Go back behind the car and observe the heater flap actuator located on the duct work on the lower left side of the engine;
8. Cycle the CCU thermostat setting from cold to hot and back to cold a few times while observing the actuator;
9. Observe the actuator retracting rotating the flap arm from the 7:00 o’clock (heat) to the 9:00 o’clock (cool air) positions as you rotate the **** on the CCU.
It is probably a good idea to run the above test any time you notice an operating change with the engine.

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