991.2 Cold Start Exhaust Sound
11-08-2017, 11:53 AM
#1
Rennlist Member
Thread Starter
991.2 Cold Start Exhaust Sound
On my 991.2 base without PSE, the idle on a cold start is around 1,400 RPM. In addition to the higher idle speed, the exhaust tone is louder and deeper.
After 30 seconds, the idle speed drops to around 600, but if I bring the RPM back to 1,400 the sound is much quieter than during the warmup period.
Does anyone know why there is a difference in sound? Do non-PSE cars have a vacuum-controlled valve that opens the exhaust up during cold start?
After 30 seconds, the idle speed drops to around 600, but if I bring the RPM back to 1,400 the sound is much quieter than during the warmup period.
Does anyone know why there is a difference in sound? Do non-PSE cars have a vacuum-controlled valve that opens the exhaust up during cold start?
11-08-2017, 12:00 PM
#2
On my 991.2 base without PSE, the idle on a cold start is around 1,400 RPM. In addition to the higher idle speed, the exhaust tone is louder and deeper.
After 30 seconds, the idle speed drops to around 600, but if I bring the RPM back to 1,400 the sound is much quieter than during the warmup period.
Does anyone know why there is a difference in sound? Do non-PSE cars have a vacuum-controlled valve that opens the exhaust up during cold start?
After 30 seconds, the idle speed drops to around 600, but if I bring the RPM back to 1,400 the sound is much quieter than during the warmup period.
Does anyone know why there is a difference in sound? Do non-PSE cars have a vacuum-controlled valve that opens the exhaust up during cold start?
I'm pretty sure during a cold start the with the PSE (I know yours is not) the valves are open to maximize the exhaust flow through the cats. It may just be something with the timing/fuel trims being adjusted after cold starts that are changing and causing the sound to settle down.
I dont believe non PSE cars have valves
11-08-2017, 12:05 PM
#3
My personal experience has been the cold start is louder while it idles in both modes. Pressing the PSE button just makes it a little lower pitched and mellow, not as raspy. If that makes sense. More bass sound I guess you could say.
11-09-2017, 12:44 AM
#5
991.2 Base without PSE:
"Downstream of the catalytic converters, the 911 Carrera basic models are fitted with a twin-branch exhaust system with (without exhaust flaps) and two oval single-tube tailpipes made from stainless steel on the left and right."
991.2 S without PSE:
"Downstream of the catalytic converters, the 911 Carrera S models are fitted with a with two inlets and four outlets, two exhaust flaps with vacuum control and two round twin tailpipes made from stainless steel on the left and right."
991.2 PSE:
"The muffler of the sports exhaust system has four inlets and two outlets. As on the Carrera S, exhaust flaps are installed that are closed by means of vacuum. At speeds above approx. 3,300 rpm, the flaps open automatically. On the sports exhaust system, the exhaust flaps can be activated directly via a button in the center console. The result is an even more flat-engine sound with a deep tone and even better power development."
11-09-2017, 10:02 AM
#7
Not quite correct. 991.2 base without PSE has no valves, 991.2 S without PSE does have valves.
991.2 Base without PSE:
"Downstream of the catalytic converters, the 911 Carrera basic models are fitted with a twin-branch exhaust system with (without exhaust flaps) and two oval single-tube tailpipes made from stainless steel on the left and right."
991.2 S without PSE:
"Downstream of the catalytic converters, the 911 Carrera S models are fitted with a with two inlets and four outlets, two exhaust flaps with vacuum control and two round twin tailpipes made from stainless steel on the left and right."
991.2 PSE:
"The muffler of the sports exhaust system has four inlets and two outlets. As on the Carrera S, exhaust flaps are installed that are closed by means of vacuum. At speeds above approx. 3,300 rpm, the flaps open automatically. On the sports exhaust system, the exhaust flaps can be activated directly via a button in the center console. The result is an even more flat-engine sound with a deep tone and even better power development."
991.2 Base without PSE:
"Downstream of the catalytic converters, the 911 Carrera basic models are fitted with a twin-branch exhaust system with (without exhaust flaps) and two oval single-tube tailpipes made from stainless steel on the left and right."
991.2 S without PSE:
"Downstream of the catalytic converters, the 911 Carrera S models are fitted with a with two inlets and four outlets, two exhaust flaps with vacuum control and two round twin tailpipes made from stainless steel on the left and right."
991.2 PSE:
"The muffler of the sports exhaust system has four inlets and two outlets. As on the Carrera S, exhaust flaps are installed that are closed by means of vacuum. At speeds above approx. 3,300 rpm, the flaps open automatically. On the sports exhaust system, the exhaust flaps can be activated directly via a button in the center console. The result is an even more flat-engine sound with a deep tone and even better power development."
I did not know this. Good info!