ari.jay.comet

Earlier this week I acquired a used 2013 991 C4S. This particular car has the PSE option/button. My prior 911 was a 2011 911 GTS (997.2) with PSE, as a reference point.

On my 997.2 you could hear a difference, even at idle. Simply pressing the PSE button would create an instant deeper/louder idle, and driving the car down the road the difference was noted at ALL RPMs. There was no mistaking the PSE being On vs Off.

However,, on this 991.1 there is absolutely no difference noticed. Even had my wife and 10 year old daughter listen, and both agreed, the car sounds equally the same with or without the PSE red LED illuminated. Is this normal?

I've read about people saying the valves on the PSE open up at 3,500+ RPM even if the PSE button isn't on (is this true?). Also, I placed my phone under the exhaust recording, with a view of the valves. Those arms didn't appear to ever move (free revving in driveway, no load). Thoughts?

I'm thinking that perhaps the PSE valves are stuck open on my car, and I say that because the car sounds louder all the time than my 997.2 GTS did (when it was stock, and PSE was on). Cold start of my 991 has a nice growl, and reminds me of the 997.2 cold start when pressing the PSE button right away.

FWIW, there was a guy selling a used AWE SwitchPath here on the forum that I bought; should arrive tomorrow. Thinking I'll install that regardless -- and see what happens there. Maybe it will be louder when on, and quieter when off. Maybe.... LOL

Jabs1542

The previous owner of the car may have 'tied off the valves' in the open position. See if you can get up in there with a flashlight and a little blind hand guiding and trace the vacuum hoses.

R_Rated

fuse may have done it too although that would keep it in quiet mode i think.

STG

Could be the change over valve (COV) gone bad. Regardless, something is wrong. Not costly. Have dealer investigate.

phx991

When I was shopping for a 991 I drove several cars with PSE, both .1 and .2, and was not able to discern a significant difference in sound inside the car with PSE on or off (other than the popping sounds in the .2 in Sport mode). I kept asking the SA if PSE was really on. On the .1 it was slightly more noticeable, especially outside the car.

Sound is subjective, but based on my experience you shouldn't expect much difference with PSE on vs off. Of course it is possible that your valves are tied off as the previous poster noted.

.2PDK

I agree as this has been my experience as well.

I've also heard the same model (991 3.4) with the Sharkwerks X-pipe, sounded much better.

StormRune

I'm pretty sure you'll find that you don't have vacuum getting to the valves, either a failed changeover valve like STG mentions, the prior owner disconnecting the lines to provide always-on sound like Jabs1542 said, or a disconnected or leaking vacuum line.

Yes the valves open anyway in the mid 3K range. You should be able to hear a change in tone even at normal idle and you should see the valves move when you press the button at idle. Just watch them while you have someone press the button. You don't need to try the revving thing to see if they work.

Also FYI the valves are open/loud when there is no vacuum (either from the button being ON or from some failure to deliver vacuum). If the valves close when you start the car the vacuum is hooked up and you are probably looking at a changeover valve failure or a leaky/disconnect vacuum line.

I think once you get the AWE switchpath on there, you are really going to want the PSE button to work, so you'll want to figure this out. You'll almost certainly find times when the AWE is too loud.

R_Rated

This sounds the most likely - would bet monies on this diagnosis.

StormRune

One more thought: If the car is under warranty, I would recommend waiting to switch to the AWE exhaust if you are going to have them check it out. I wouldn't want to change to risk changing out some exhaust stuff before having them take a look just in case they would then choose to deny coverage due to exhaust-related aftermarket work... even if the root case turned out to be unrelated.

ari.jay.comet

Car is not under warranty (Feb-2013 in service date). Purchase price reflected this nicely, which is part of why I jumped at the chance to get back into a P-car after missing my 997.2 so much lately, haha!

As such, I'm planning to diagnose myself, and repair accordingly. Have a few friends who are Porsche people and shade tree mechanics, so I don't expect too much issue there. But any help with regards to the "change over valve" (COV) and where to find this would be appreciated. I assume that is the electronic valve mounted on the passenger side of the motor that I saw earlier in my online research?

R_Rated

Did you buy from a Porsche dealer recently? If so.... I bet they'd do a good faith fix.

ari.jay.comet

It was from a third party "exotic" type dealership. They did have a very pretty McLaren and Gallardo there! But they are 3.5 hours drive away, so kind of doubt they are going to handle this for me on their dime (35k miles, 4 year old car, etc).

StormRune

Here are your valve locations. It's also pretty easy to check to see if the vacuum line is disconnected between the engine carrier and the exhaust by looking up under the center of the exhaust for the braided steel vacuum line.

ari.jay.comet

QUICK UPDATE
Took a break at work to run outside and see what I could see.

HOSES are indeed there, including the braided steel vacuum line.

VALVES open/close by hand. Driver side one was free moving, but the passenger one felt slightly seized-- but under minor pressure did close, and I pushed the arm a few times. It feels "free" moving now. Fact that it was so firm/seized makes me think it has not open/closed in a LONG time.

VACUUM pressure? Dunno. I'd need a vacuum gauge I assume? Granted I'm at work, so assume there isn't an easy way to test if there is vacuum in the line when the car is running. But something tells me there isn't vacuum in the lines.

CVO (change over valve) is probably the culprit as someone said earlier. OF course it could be the line/hoses is disconnected on the motor side of the metal shield but that isn't easy to diagnose at work!

PARTS are on order, though. Called local Porsche dealer, to get two new exhaust gaskets (center muffler to mani/CAT) (used ones are coming with used AWE muffler, but prefer new). My cost was under $40 for the COV, in-stock .. so I'll pick that up tomorrow when the exhaust gaskets arrive.

PLAN then is to further diagnose the vacuum issue at the same time as installing the AWE SwitchPath; assuming right now the COV is the issue; swap that, install AWE, and then quiet non-PSE mode should hopefully be much more quiet than it is now (read: happy wife) and loud will be louder (read: happy me!)

Thoughts?

Needsdecaf

Sounds like you're on the right track.

You should DEFINITELY hear a difference, even at idle.