DavidBur

Hi guys!
I have noticed on my Cayman GT4 that those two exhaust valves on stock exhaust are only open during cold starts. Thats why cold starts are louder, however after 10 seconds after cold start valves automaticly close.

Even when the sport mode and PSE button is active, valves are still closed, nothing happens.
The only difference is that you can occasionally hear some pops on gear change or lift-off with sport mode. But there is no other difference and valves are still closed during driving in sport mode.

Do you experience the same with your car aswell?
Any ideas why it is set like this?

Jimmy-D

Valves should open over certain rev range. I replaced the stock exhaust with an FVD valveless sport exhaust but you can also disconnect and keep you valves open all the time. I highly recommend doing this

DavidBur

I will try asking my service to keep the valves open, to prevent being accused for some "modification".
Do you think it is safe thing to do? It might trigger some Check Engine light no?

However I don't think that the valves are open only by high revs. At least not on my car.
The only possible time when they might be open is during full throttle over 4,500RPM.

fifthspadz

I have had my valves open since day one. Zero check engine light. Zero issues

KareemGT4

You have an exhaust button that keeps them open.

DavidBur

I forgot to mention in the original post. By the sport mode I also meant that exhaust button.

The only difference when the exhaust button is ON are some pops on shifting and lift-offs.

But when you press the button while driving theres no sound difference.
When pressing while stacionary they don't open.

GAZZ

Bit of bad luck for that (USA build).
Depending on your country it can work differently.
Australia build config is such that press the exhaust button and it ALWAYS stays open, no matter the rev.

bretster

I wonder if a US car could be changed to operate as described above?

d00d

Here's some information;
https://rennlist.com/forums/gt4/9318...ud-noises.html

DavidBur

Thanks! Very usefull!

Ferrarisimo

Has anyone had any luck getting their SA to flash their PSE behavior to mimic other countries', so that the exhaust button always opens the valves no matter the circumstances?

Spyerx

Your car is louder with cold starts due to the air injection system. Not exhaust valves. You should hear my GT3 on startup and it's got no valves (they're removed).

d00d

There is no air injection pump on the GT4, but you're right that it's not an exhaust valve issue (it closes within a second), the loudness is due to altered timing that helps the catalysts warm up similar to what air injection does.

VLJ

on my 991 C2S I disconnected the vacuum lines and plugged them to keep the valves open 100% of the time, worked great. Can we do the same on these cars? My 991 did not have PSE

d00d

Yes you can, more information at that link.