Originally Posted by robbonds

i took the advice from people here and disconnected the wire in the back (with orange connector). the exhaust defintely sounds louder and stays on all the time..i think i like it this way.

it took about 3 seconds

Just want to make sure that this isnt hurting anything...anyone know for sure?

i guess if a problem develops i can reconnect before taking to dealer

Originally Posted by robbonds

...i guess if a problem develops i can reconnect before taking to dealer

Originally Posted by Carbon_Ted

This would be my plan too. I would even go a step further- that anytime the car goes in for service, oil change or whatever, I would reconnect..esp since it's easy to do. Here is an interesting thread from another board describing a possible side effect over time, but it may be an aberration moreso than not. I cannot recall any other 997 owners having reported this problem across the various p-car websites: http://www.rennteam.com/showflat.php...=&fpart=1&vc=1
So Rob, just to clarify- sorry if this is awkwardly stated: you think it's louder now at identical rpm than in (non-cutoff) 'open' mode via Sport button before?

Originally Posted by robbonds

Are there other people doing this?

Originally Posted by mdrums

I talked to my dealer about the PSE and how it work's and the way I understand it is when the sport chrono is selected or for those with out the chrono PSE is selected it sends a signal to the PSE to open a valve and divert the exhaust in a little bit of a more straight through route(ie exhaust goes through a different chamber in the muffler that does not absorb sound). My understanding is that PSE offers no performance advantage just a sporty sound.

So I have no idea nor does the dealer on how running PSE all the time could adversly affect the engine. What is the difference in PSE and a Tubi sport exhaust system to the engine anyway?

Originally Posted by allegretto

When you disconnect you undoubtedly affect back pressure in the exhaust system. This possibly has an upstream effect on the amount of time it takes to fill the combustion chamber and therefore upon timing issues. I don't know about the Porsche in specific, but I do know that in general timing is the difference between BIG HP and detonation/damage.

Others have advanced that, hey , what's the big deal? It's no worse than just leaving the unit set to "Sport". Perhaps so, perhaps not. We all have noticed how much more responsive the engine is in Sport Mode. No doubt the EMS/ECU has a different curve in Sport and that may include timing (almost certainly it does).

So, if you open the valve but don't change the timing, perhaps there is a rub. Alternatively, it is possible that high PRM is fine but low RPM, which Porsche engineers have every reason to believe that we wont use in Sport Mode for long, is not so fine.

Then again, maybe I'm going in exactly the wrong direction...

Originally Posted by Orient Express

The valve flap that your service director is talking about is the one that closes to make the exhaust go completely through the PSE muffler. When this flap is closed the muffler is in the "Quiet" position.

The flap is moved by a vacuum actuator that makes sure the flap is in the open position by default (when there is no vacuum on the actuator) or when the actuator fails.



The only way that the flap would start "flapping" around is if the actuator arm came off of the flap pivot ball. It is extremely unlikely that would happen in normal use. If it were to come off, then one just reaches up and snaps the arm back on the pivot ball.

The actuator arm coming off of the flap pivot has nothing at all to do with the disconnection of the vacuum switch, which is the popular hack to keep the exhaust loud all of the time.



This is true for both the 996 (pictured) and the 997.

Originally Posted by Orient Express

The flaps are controlled by the vacuum actuator as seen in the first picture in my earlier post.

The hack that everyone does on the 997 is to disconnect the electrical connector on the vacuum switch that controls the actuators. This is the brown electrical connector in the second picture. This would be the same if power was removed from the vacuum switch by pulling a fuse. (however in the 997, electrical power to the vacuum switch is provided by the DME, and the power line to the switch does not have an inline fuse).

As long as the vacuum actuator linkage is connected to the flap, the flaps are held in the "Open" position. The vacuum actuators have a spring inside of them that holds the flap open and prevents the linkage from moving freely.

So your technician is partially right. With no vacuum at the actuator, the flaps are open (the default position), but they do not move freely because of the actuator spring.

There is nothing to worry about with having the electrical connection to the PSE vacuum switch disconnected.

Originally Posted by Orient Express

Which is better?

Both do exactly the same thing, which is preventing the muffler flap actuator from moving the flap. The sound of the exhaust will be exactly the same with both solutions.

If you choose the "disconnect the vacuum hose" route, just make sure that the supply side line is plugged so that you do not put a leak in your intake system. This can potentially trigger a CEL fault light because the system will think that it is running too lean because of the additional air going into the intake manifold. Remember that in the default mode the exhaust flap actuators are vented to the atmosphere (no vacuum) and the spring inside the actuator keeps the valve open.

I prefer to simply disconnect the electrical connection to the vacuum switch. This keeps the integrity of the intake system safe. The only additional thing that I would do is to cover the ends of the electrical connectors to prevent contamination from accumulating on the wiring pins.

As a side note, if there is a 997 center console faceplate that has room for an additional switch, it is not difficult at all to add the non-chrono exhaust switch and power it directly from the fuse panel to turn on and off the quiet mode of the exhaust manually.

The only time the vacuum lines (after the vacuum switch) are active is when the exhaust is in the "quiet" mode.

If the vacuum lines were completely removed, then the exhaust would be in its default mode (loud) all of the time. If the vacuum switch is retained, then the vacuum lines are disconnected on the output side of the switch, and the output outlet is plugged. Regardless of which side of the vacuum switch the line is disconnected, The source side of the vacuum line must be plugged.

Try this simple test, with the car idling, pull the "Y" connector from the output side of the vacuum switch and feel the outlet on the switch for vacuum. There will be none. This is because the default position of the vacuum switch is off (not powered from the DME) or closed. And when the muffler actuators do not have vacuum, their default state is to have the flapper valve "open" in the "loud" mode.

The definitive answer:

No potential for any damage, no, none, nada, nyet, nr, non, apiø, nessun damage.

Just unplug the electrical connector and be done with it

Originally Posted by Matt(inMA)

There is NO static timing on Porsche's, or any other modern car for that matter - heck, running the exhaust in "sport" mode will do NOTHING to your car except make it more fun to listen to. All after market exhaust are "sport" exhaust and they are not causing any issues.

Just go enjoy that baby!!!

Matt

Originally Posted by allegretto

When you disconnect you undoubtedly affect back pressure in the exhaust system. This possibly has an upstream effect on the amount of time it takes to fill the combustion chamber and therefore upon timing issues. I don't know about the Porsche in specific, but I do know that in general timing is the difference between BIG HP and detonation/damage.

Others have advanced that, hey , what's the big deal? It's no worse than just leaving the unit set to "Sport". Perhaps so, perhaps not. We all have noticed how much more responsive the engine is in Sport Mode. No doubt the EMS/ECU has a different curve in Sport and that may include timing (almost certainly it does).

So, if you open the valve but don't change the timing, perhaps there is a rub. Alternatively, it is possible that high PRM is fine but low RPM, which Porsche engineers have every reason to believe that we wont use in Sport Mode for long, is not so fine.

Then again, maybe I'm going in exactly the wrong direction...