fbroen

What is the purpose of the exhaust valve in a non PSE exhaust?

Does it "tune" back pressure to a better level at lower revs when it is closed? That is, are there any advantages for the engine by having a closed exhaust valve at lower revs?

Or it is it just to eliminate droning at lower RPMs?

I say droning, because my changeover valve has failed and is on order. Exhuast still sounds great over 3000 rpm, but under that, it is all Civic-with-a big-exhaust-pipe sounding droning in the cabin. I guess the exhaust is designed to work with the changeover valve operating....

neanicu

Probably both.

There's definitely an advantage having a little more back pressure at lower RPM because of the increase in torque.

fbroen

But no harm in driving it, right? I figured not, but I am no engineer....

neanicu

No harm.

How did you know yours is faulty? Just curious...
Did you get a CEL?

Larry Cable

as long as it is always open and not always closed...

Contadino

I tried the hack of disconnecting the vacuum lines that operate the valves. Non PSE C2S. Sounded exactly as you described- terrible! Quickly reconnected them.

911.Forever

Is your car equipped w Sport Chrono? I think this valve set up (the single rear muffler) links to the SC button.
On my 991 S cab: Regarding capturing a beautiful exhaust note, I installed a used PSE muffler purchased from a fellow forum member, and added the Fister side cans. The exhaust note is second to none and done completely on the cheap. JMHO.

StormRune

I'm 98% certain that valve only opens when the car hits roughly 3800 RPM regardless of the Sport Chrono setting with the non-PSE muffler setup. The PSE button is the only OEM button setup that can cause an earlier opening of the valve.

PCA1983

I bought a new Macan Turbo in 2015 during the fuel line recall for a big discount because i was willing to wait through the parts shortage. It had a great sound at startup, but quickly became quiet in less than a minute. Then i read about an electrically actuated valve on the muffler that did this. But it was impossible to reach with my hands and fingers. So i purchased a pair of super long needle nose pliers and an extra long screwdriver at Harbor Freight. I laid on the ground behind my Turbo with my extra long tools. Lo and behold, the wire plug to that exhaust valve "fell off". Now the extra exhaust noise stayed from startup till shutdown. It sounded much better, but not quite as good as PSE does when turned on. My guess is that all non-PSE Porsches have this valve. It might help heat and activate the cats more quickly. Whatever, i liked it. But i would still prefer the PSE like what my 911 has.

Rennolazine

This was the exact same sequence of events that occurred before i did an aftermarket exhaust...lol. i will say the muffler delete was a little too crazy sounding. Like a tiger was eating a polar bear during a rambo movie
The macan sounded so mean though. Im super happy with the akra on the 911 because it sounds much less ricey and you can tone it down in the different modes.