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997.1 PSE Operation - How does it work?

ThreeSixNine

New member
Joined
20 Feb 2020
Messages
2
Hi,

Can anyone comment on how the PSE operates exactly?

Do the valves open and close based on engine torque demand (Throttle position & RPM) or is it merely based on RPM?

Does the car always start on loud/valves open during a cold start?

I heard that if you are driving it comes off/closed at 30mph and comes back on at 50mph - because of some noise regulations or emissions.

How does it behave on the motorway? Can I cruise at 80mph or 3500 RPM with the valves closed if I have small throttle input? That would be my ideal scenario, I don't want the car on loud when I am doing long roadtrips at 80MPH.

Thanks.
 
If it's like the 996 then it's speed related to satisfy drive by noise regs etc... if PSE is on, it's valves open between 0-30mph, then closed between 30-50mph, then open again.

If you want valves closed at 70mph cruise, then switch PSE off.

It will default to open on start up (at least my 996 does) but you can close the valves before you start.

It's not a drony noise so not bothersome when active.
 
ThreeSixNine said:
Hi,

Can anyone comment on how the PSE operates exactly?

Do the valves open and close based on engine torque demand (Throttle position & RPM) or is it merely based on RPM?

Does the car always start on loud/valves open during a cold start?

I heard that if you are driving it comes off/closed at 30mph and comes back on at 50mph - because of some noise regulations or emissions.

On the 997.1 the PSE only operates when you press the sports exhaust button on the centre console.

More detailed fault finding info here - http://911uk.com/viewtopic.php?t=132422
 
My understanding is that the ECU controls the PSE vacuum valves, so if PSE is switched on the valves are open at idle, then closed as revs rise and then open again at around 3500 rpm. So its basically rpm related, not load dependant.

I'm guessing the way its been programmed is for noise and emissions considerations.

I'm of the opinion that its better to control the PSE so the valves remain open or closed 100% of the time at any revs. And that the car can be started from cold in quiet mode.

If you search on this forum for "Retrofitting PSE Switch" you'll see a few of us have used a relay mechanism to switch the PSE (or an aftermarket valved exhaust) in or out, so its not controlled by the ECU any longer. The relay also remembers what setting was last used when the ignition is switched off / back on.
 
JonnieD said:
My understanding is that the ECU controls the PSE vacuum valves, so if PSE is switched on the valves are open at idle, then closed as revs rise and then open again at around 3500 rpm. So its basically rpm related, not load dependant.

Do bear in mind that the Gen1 and Gen2 PSE set-ups are not the same.
 
TonyC911 said:
JonnieD said:
My understanding is that the ECU controls the PSE vacuum valves, so if PSE is switched on the valves are open at idle, then closed as revs rise and then open again at around 3500 rpm. So its basically rpm related, not load dependant.

Do bear in mind that the Gen1 and Gen2 PSE set-ups are not the same.

I know that, I was answering the question which related to the 997.1 per the thread title :thumb:

I'm not sure anyone has definitively spelt out the differences between the Gen 1 and 2 PSE as it seems it depends on which country you are in as to how it operates. The common factor is that the PSE is controlled by the ECU in both gens. But the switching is different where the Gen 2 always has a separate PSE switch whereas that wasn't always the case with the Gen 1.
 
JonnieD said:
My understanding is that the ECU controls the PSE vacuum valves, so if PSE is switched on the valves are open at idle, then closed as revs rise and then open again at around 3500 rpm. So its basically rpm related, not load dependant.

I'm guessing the way its been programmed is for noise and emissions considerations.

I'm of the opinion that its better to control the PSE so the valves remain open or closed 100% of the time at any revs. And that the car can be started from cold in quiet mode.

If you search on this forum for "Retrofitting PSE Switch" you'll see a few of us have used a relay mechanism to switch the PSE (or an aftermarket valved exhaust) in or out, so its not controlled by the ECU any longer. The relay also remembers what setting was last used when the ignition is switched off / back on.

I had a little search and understand the principles, however do you have a step by step DIY for retrofitting a relay? I have an disused button under my steering wheel which was used for some crap hidden parking sensors installed by the previous owner which I would like to repurpose.
Any help would be appreciated.
 
TFR said:
JonnieD said:
My understanding is that the ECU controls the PSE vacuum valves, so if PSE is switched on the valves are open at idle, then closed as revs rise and then open again at around 3500 rpm. So its basically rpm related, not load dependant.

I'm guessing the way its been programmed is for noise and emissions considerations.

I'm of the opinion that its better to control the PSE so the valves remain open or closed 100% of the time at any revs. And that the car can be started from cold in quiet mode.

If you search on this forum for "Retrofitting PSE Switch" you'll see a few of us have used a relay mechanism to switch the PSE (or an aftermarket valved exhaust) in or out, so its not controlled by the ECU any longer. The relay also remembers what setting was last used when the ignition is switched off / back on.

I had a little search and understand the principles, however do you have a step by step DIY for retrofitting a relay? I have an disused button under my steering wheel which was used for some crap hidden parking sensors installed by the previous owner which I would like to repurpose.
Any help would be appreciated.

No worries.

Have you looked at this thread? http://911uk.com/viewtopic.php?t=116327&highlight=retrofitting+pse+switch I think this is the correct way to link a thread here.

I know its a long, but the principles and DIY instructions are all embedded in there, its evolved as some have taken there own slightly different route to implement it. You'll see towards the end in post 251 I've posted an updated diagram, using the latching relay I used, plus the wiring pins near the centre console you need to tap into.

You should have no problem using your button rather than the PSE switch as long as its a toggle (push to contact) type, not a switch.

Post back here of at that thread if you need any more help :thumb:
 
JonnieD said:
TFR said:
JonnieD said:
My understanding is that the ECU controls the PSE vacuum valves, so if PSE is switched on the valves are open at idle, then closed as revs rise and then open again at around 3500 rpm. So its basically rpm related, not load dependant.

I'm guessing the way its been programmed is for noise and emissions considerations.

I'm of the opinion that its better to control the PSE so the valves remain open or closed 100% of the time at any revs. And that the car can be started from cold in quiet mode.

If you search on this forum for "Retrofitting PSE Switch" you'll see a few of us have used a relay mechanism to switch the PSE (or an aftermarket valved exhaust) in or out, so its not controlled by the ECU any longer. The relay also remembers what setting was last used when the ignition is switched off / back on.

I had a little search and understand the principles, however do you have a step by step DIY for retrofitting a relay? I have an disused button under my steering wheel which was used for some crap hidden parking sensors installed by the previous owner which I would like to repurpose.
Any help would be appreciated.

No worries.

Have you looked at this thread? http://911uk.com/viewtopic.php?t=116327&highlight=retrofitting+pse+switch I think this is the correct way to link a thread here.

I know its a long, but the principles and DIY instructions are all embedded in there, its evolved as some have taken there own slightly different route to implement it. You'll see towards the end in post 251 I've posted an updated diagram, using the latching relay I used, plus the wiring pins near the centre console you need to tap into.

You should have no problem using your button rather than the PSE switch as long as its a toggle (push to contact) type, not a switch.

Post back here of at that thread if you need any more help :thumb:

Thanks for the reply, unfortunately too complicated for me! Back to the drawing board, but it may end up being a Carnewal remote, which I was hoping to avoid! Cheers
 
TonyC911 said:
ThreeSixNine said:
Hi,

Can anyone comment on how the PSE operates exactly?

Do the valves open and close based on engine torque demand (Throttle position & RPM) or is it merely based on RPM?

Does the car always start on loud/valves open during a cold start?

I heard that if you are driving it comes off/closed at 30mph and comes back on at 50mph - because of some noise regulations or emissions.

On the 997.1 the PSE only operates when you press the sports exhaust button on the centre console.

More detailed fault finding info here - http://911uk.com/viewtopic.php?t=132422

Not necessarily true.....I have a very late build 997.1 C4S (built late 2008 and registered March 2009). It has a switchable PSE button that can be operated at any speed. It also has a separate sport button which sharpens the throttle response and drops the suspension by 10mm....but doesn't alter the exhaust. Don't know if 's a hybrid of sorts because it was ordered as a demo car from the factory and has full leather (including seat backs and dashboard), alcantara headlining, heated seats , illuminated door sills, Turbo wheels etc.
Not sure if all C4S models have all the above but mine seems to be packed with toys, which has encouraged me to leave it alone and not modify. It's exactly as it came from the factory including the wheels. :thumb:
 
TFR said:
JonnieD said:
TFR said:
JonnieD said:
My understanding is that the ECU controls the PSE vacuum valves, so if PSE is switched on the valves are open at idle, then closed as revs rise and then open again at around 3500 rpm. So its basically rpm related, not load dependant.

I'm guessing the way its been programmed is for noise and emissions considerations.

I'm of the opinion that its better to control the PSE so the valves remain open or closed 100% of the time at any revs. And that the car can be started from cold in quiet mode.

If you search on this forum for "Retrofitting PSE Switch" you'll see a few of us have used a relay mechanism to switch the PSE (or an aftermarket valved exhaust) in or out, so its not controlled by the ECU any longer. The relay also remembers what setting was last used when the ignition is switched off / back on.

I had a little search and understand the principles, however do you have a step by step DIY for retrofitting a relay? I have an disused button under my steering wheel which was used for some crap hidden parking sensors installed by the previous owner which I would like to repurpose.
Any help would be appreciated.

No worries.

Have you looked at this thread? http://911uk.com/viewtopic.php?t=116327&highlight=retrofitting+pse+switch I think this is the correct way to link a thread here.

I know its a long, but the principles and DIY instructions are all embedded in there, its evolved as some have taken there own slightly different route to implement it. You'll see towards the end in post 251 I've posted an updated diagram, using the latching relay I used, plus the wiring pins near the centre console you need to tap into.

You should have no problem using your button rather than the PSE switch as long as its a toggle (push to contact) type, not a switch.

Post back here of at that thread if you need any more help :thumb:

Thanks for the reply, unfortunately too complicated for me! Back to the drawing board, but it may end up being a Carnewal remote, which I was hoping to avoid! Cheers

No worries.

Its really not that complicated though. But also, you might find an electrical car specialist who would do that for you. Given the cost of the Carnewal unit, I'm sure someone would install it into your switch with the relay cheaper.

I think those remote solutions with the dongle are a real pain in the neck. I've still got the unused remote unit etc from my Top Gear system that I didn't want to use.

I'm assuming your car already has the exhaust and valves already in place?
 

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