Exhaust note with PSE on/off and the vacuum line
05-12-2018, 12:31 AM
#1
Rennlist Member
Thread Starter
Exhaust note with PSE on/off and the vacuum line
Edited!!
Everything started the day I pushed my car to 9K rpm. Drove it hard and had a blast. Coming home, I noticed something was off, too much noise, really too much. My first thought was that I was pumped with adrenaline and was overhearing things. But no, the next few times I took her out, I noticed huge amount of noise I never heard before, especially at lower RPMs. Then I tried the PSE button, and, yes, no difference whether being on or off. Now I remembered reading lots of threads and discussion about this on RL regarding the vacuum line. So I came home and discovered the left vacuum line to be disconnected. So what now? I started scratching my head and thinking.
1. Pushing the PSE while idling or at low RPMs opens the valves and makes the exhaust note louder.
2. Getting the car above about 3.5K rpm something else happens, where either valves or not sure what makes more noise.
3. Vacuum line connected, when one presses the PSE button, the valves on the exhaust change position, and the exhaust makes more noise.
4. The vacuum line disconnected and PSE off, I feel vacuum and suction on the hose side and nothing on the solenoid side.
5. Pressing the PSE, no suction or vacuum can be felt on either side.
In my original post, I had made some naive omissions and conclusions. But I am still trying to understand how this whole system works. Valves open when one presses the PSE button. What else happens at 3.5k rpm? Valves are already open, are there secondary valves? In my 991.2 GT3 case, this second and more pronounced exhaust note change happens at about 3.5k RPM and is variable depedning on gear and throttle input. In 5th or 6th gear, with gentle throttle input, exhaust note becomes significantly louder at 3k RPM. When in 3rd gear with heavy foot on the throttle, this louder noise does not come on until 4k rpm. I'm not dreaming, the full exhaust note on my car is variable anywhere between 3k to 4k rpm depending on gearing and throttle input. I would appreciate if you guys can try this out, there may be something wrong with my car. My .1 GT3 did not open up until 3.5k rpm, and it was repeatable.
...and whoever read my orginal post, too excited, too soon. Felt like back at the bench. lol. Forgot to mention, I love the new exhaust sound with the vacuum line disconnected. It will definitely stay off.
Everything started the day I pushed my car to 9K rpm. Drove it hard and had a blast. Coming home, I noticed something was off, too much noise, really too much. My first thought was that I was pumped with adrenaline and was overhearing things. But no, the next few times I took her out, I noticed huge amount of noise I never heard before, especially at lower RPMs. Then I tried the PSE button, and, yes, no difference whether being on or off. Now I remembered reading lots of threads and discussion about this on RL regarding the vacuum line. So I came home and discovered the left vacuum line to be disconnected. So what now? I started scratching my head and thinking.
1. Pushing the PSE while idling or at low RPMs opens the valves and makes the exhaust note louder.
2. Getting the car above about 3.5K rpm something else happens, where either valves or not sure what makes more noise.
3. Vacuum line connected, when one presses the PSE button, the valves on the exhaust change position, and the exhaust makes more noise.
4. The vacuum line disconnected and PSE off, I feel vacuum and suction on the hose side and nothing on the solenoid side.
5. Pressing the PSE, no suction or vacuum can be felt on either side.
In my original post, I had made some naive omissions and conclusions. But I am still trying to understand how this whole system works. Valves open when one presses the PSE button. What else happens at 3.5k rpm? Valves are already open, are there secondary valves? In my 991.2 GT3 case, this second and more pronounced exhaust note change happens at about 3.5k RPM and is variable depedning on gear and throttle input. In 5th or 6th gear, with gentle throttle input, exhaust note becomes significantly louder at 3k RPM. When in 3rd gear with heavy foot on the throttle, this louder noise does not come on until 4k rpm. I'm not dreaming, the full exhaust note on my car is variable anywhere between 3k to 4k rpm depending on gearing and throttle input. I would appreciate if you guys can try this out, there may be something wrong with my car. My .1 GT3 did not open up until 3.5k rpm, and it was repeatable.
...and whoever read my orginal post, too excited, too soon. Felt like back at the bench. lol. Forgot to mention, I love the new exhaust sound with the vacuum line disconnected. It will definitely stay off.
Last edited by gago1101; 05-12-2018 at 01:51 AM.
05-12-2018, 05:16 AM
#2
Burning Brakes
Vacuum line needs to be plugged air tight, otherwise you'll get an error message.
My car is incoming so can't verify myself yet, but the engine has variable length intake pipes, or different modes in the intake system. The modes are depending on speed and load. Are you sure you're hearing differences in the exhaust sound, or couldit in fact be the intake sound? Once the PSE is open, it's open.
My car is incoming so can't verify myself yet, but the engine has variable length intake pipes, or different modes in the intake system. The modes are depending on speed and load. Are you sure you're hearing differences in the exhaust sound, or couldit in fact be the intake sound? Once the PSE is open, it's open.
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Leslie Woodcock (09-24-2021)
05-12-2018, 09:28 AM
#3
Happened to me 3x, similar circumstance to you pushing car hard. The clamp that kept the vacuum line on wasn’t staying put.
You can actually look under the car on the left side and see the vacuum lines and it will be obvious what the issue is.
Dealer ordered and installed new clamps and issue hasn’t returned
You can actually look under the car on the left side and see the vacuum lines and it will be obvious what the issue is.
Dealer ordered and installed new clamps and issue hasn’t returned
05-12-2018, 11:15 AM
#4
Nordschleife Master
Vacuum line came loose on the actuator side on the driver side?
Happened to me and my buddy as well. It's a manufacturing problem. It's fails on a lot of cars. I think Porsche made the rubber tube too short. The failure robbed me 3 sessions on track at laguna because I couldn't pass sound. The line blew off one session. I zip tied it back on and it blew off again and I failed sound again. I lost a third session because I had to drive into town to find a replacement vacuum line.
Happened to me and my buddy as well. It's a manufacturing problem. It's fails on a lot of cars. I think Porsche made the rubber tube too short. The failure robbed me 3 sessions on track at laguna because I couldn't pass sound. The line blew off one session. I zip tied it back on and it blew off again and I failed sound again. I lost a third session because I had to drive into town to find a replacement vacuum line.
05-12-2018, 11:57 AM
#5
Vacuum line came loose on the actuator side on the driver side?
Happened to me and my buddy as well. It's a manufacturing problem. It's fails on a lot of cars. I think Porsche made the rubber tube too short. The failure robbed me 3 sessions on track at laguna because I couldn't pass sound. The line blew off one session. I zip tied it back on and it blew off again and I failed sound again. I lost a third session because I had to drive into town to find a replacement vacuum line.
Happened to me and my buddy as well. It's a manufacturing problem. It's fails on a lot of cars. I think Porsche made the rubber tube too short. The failure robbed me 3 sessions on track at laguna because I couldn't pass sound. The line blew off one session. I zip tied it back on and it blew off again and I failed sound again. I lost a third session because I had to drive into town to find a replacement vacuum line.
05-12-2018, 05:47 PM
#7
Drifting
Apparently when you are idling and press PSE button, valves open = louder exhaust. But then when you actually get in gear and go, the valves close again. But then will open after 3.5K - 4K RPM. Seems like the PSE button is a bit useless to be honest.
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05-12-2018, 08:31 PM
#10
Rennlist Member
Thread Starter
05-13-2018, 03:32 AM
#11
Rennlist Member
Thread Starter
The question I have now, why is the line coming off when pushing the car hard? I do not think it's caused by the movement of the exhaust or the line while driving, both are pretty sturdy and secure. Is there a back pressure created at the junction at high rpm causing the line to pop open? I'm thinking to cap the vacuum line, but leave the solenoid / exhaust side open.
05-13-2018, 04:44 AM
#12
The question I have now, why is the line coming off when pushing the car hard? I do not think it's caused by the movement of the exhaust or the line while driving, both are pretty sturdy and secure. Is there a back pressure created at the junction at high rpm causing the line to pop open? I'm thinking to cap the vacuum line, but leave the solenoid / exhaust side open.
05-13-2018, 12:09 PM
#13
Nordschleife Master
I think it's because the line is too short. When you push the line back on you can see it doesn't seat nicely. The motion that occurs causes it to slide off
05-13-2018, 12:49 PM
#14
Rennlist Member
Exact same thing happened to me. Drivers side vacuum tube popped off on the track. Shop had an identical clamp and I put that on and it popped off again. Finally had track side shop wire tie the crap out of it and it’s been good since.
05-13-2018, 01:25 PM
#15
