PSE not switching off

[Windy_Miller]

On my 2010 987.2 S
Ssymptoms:
1) day 1 - raspy-rattle from exhaust after start up that went if PSE engaged
2) day 2 - no apparent PSE ‘off’ functionality.

On the 987.2 the PSE is on (ie ‘loud’) upon first starting the car, then, as vacuum is created by the pump (running off the crankshaft I believe) it passes through a solenoid-switch in the engine compartment to the valve actuators (one on each rear silencer) and operates them, to
move a push-rod that moves a flap in the silencer to switch the PSE to ‘quiet’/off mode.


when you press the PSE button this operates the solenoid switch (via a control unit under the passenger seat I believe) to remove the vacuum from the valve actuators, allowing the push rods to ‘relax’ to their initial position, moving the silencer flaps and thus putting the PSE into ‘loud’ mode.

Both PSE valve actuators have full free range of movement by hand - these are known to have a tendency to stick in one position or other.


The ‘push-rods’ from the actuators to the silencers are undamaged and appear connected - these can sometimes snap.

The vacuum pump is assumed to be working as it provides vacuum to other systems (eg brakes servo), and these work, so.... ?????


I replaced the Vacuum solenoid switch in the engine compartment with a brand new one from Porsche. During fitting I checked the vacuum draw to/from the 2 pipes connecting to the solenoid and they seem
fine (so assuming no holes/leaks in these pipes).


so I’m at a bit of a loss now. The only other ‘component’ in the PSE system is one of the electronic control units through which the PSE operation signals pass.

or, both actuators have simultaneously failed - ie, I assume they contain some sort of membrane against which the vacuum draws and perhaps this can tear? But how likely that both fail at the same time? ??


ok, so it’s not the worst problem in the world to have that I can’t switch off my sports exhaust, but it bugs me that I have a switchable exhaust that isn’t working ??

any thoughts greatly appreciated ??

 

[Motorhead]

Jason,

I thought originally that this video (posted on the Boxster forum recently) might be of help, but if you've actually replaced what he refers to the change-over valve it sounds as though it's something else.

https://www.youtube.com/watch?v=nC4VGnYJ4QM&feature=youtu.be

It seems more likely that your problem is electrical in nature and could well lay with the PSE control unit you mention, although I've no idea where that could be located. Rather than faff around changing expensive electrical components it probably would be more efficient to run some Porsche-specific diagnostics to locate the fault.

Jeff

 

[Windy_Miller]

Bit of an update on this -

Used a mates ramp to get the car up and using his hand-held vacuum pump and by process of elimination (disconnecting each tube / braided hose in turn and applying vacuum to see if it did / didn’t hold) I’ve confirmed it’s actually the LHS (passenger) exhaust vacuum unit (the thingy that sits on the outside of the back box and operates the push rod that openS/closes the butterfly valve in the box)

on D911 an OE Porsche one is £105+VAT+P&P!

or they do a design tek one for £38+VAT+P&P.

clearly I’d rather buy the design tek one on price alone. Anyone used these? Are they as good quality as OE? Anyone used anything else instead - e.g., Helical?

also anyone changed one - I think it’s a rear bumper off job, though possibly doable with bumper on with small hands and if the bolts that hold it onto the inverted bracket aren’t seized.

 

[Motorhead]

No recommendations I'm afraid Jason, but at least one of the aftermarket exhaust suppliers (Fabspeed) uses Helical aerospace-quality actuators, so I suppose that's some sort of recommendation. It seems that they're used on the Porsche GT3 RS.

Jeff

 

[JohnCRS]

Have you tried your OPC for a price? With the club 10% discount you might get a better price on the OEM part.

The other thing I would try, as you have little to lose, is to see if you can free it off. A pair of mole grips and some penetrating oil might do the trick.

Good luck.

 

[Windy_Miller]

Thanks Jeff - I’ll try contacting g helical direct, though I’m assuming they’ll only deal with trade.

Thanks John, yes the OPC price is £104 (incl VAT), and then I’ll get my 10% club discount. But it’s a 50mile round trip to my nearest OPC, so the amount I spend on fuel there and back eats up the discount. Also the D911 design tek one would still come in at ~half the price. But I don’t want to just buy the design tek on on price alone, if it’s poor quality And won’t last.

its not seized, it’s simply not holding a vacuum, so Ive concluded that the diaphragm inside it has split / torn / perforated.

 

[Motorhead]

Jason,

Just to add that any item with the label 'aerospace quality' attached like the Hellical unit generally means a doubling of the price - at least.! If Porsche use it on their race cars it's bound to be much more robust than the standard item though.

Incidentally, I'm sure that your Porsche Dealership would post you the actuator, which would work out cheaper than D911 if you choose to go Porsche OE.

Jeff