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    PSE tech talk (not the usual q's!)

    Having done the PSE electric switch fix in my 997S, heres what ive noticed:

    - Revving the car in N, the sound is really MUCH less than it was before I disconnected the switch. This is something that really makes no sense to me! However, while driving the sound is MUCH louder!

    - The car sounds MUCH louder when the exhaust is cold, for some wierd reason. After a lot of heavy-footed driving, the sound gets quieter, and you no longer hear the 'tone' (growl sound etc) of the PSE, you just hear the sound of hot air.


    I got another friend to disconnect his electric switch too on his car and he noticed the exact same thing on his PSE too, so im guessing this is no anomaly. What is the technical explanation behind it though? Just out of interest, its good to know these things .

    Thanks for the replies!

    Re: PSE tech talk (not the usual q's!)

    If anybody knows, it's Orient Express. He seems to be the PSE guru on Rennteam

    Re: PSE tech talk (not the usual q's!)

    I neutral there is no load - once you are driving the engine is working harder and makes more noise.

    Sound differences

    Which switch did you disconnect? The vacuum switch in the engine compartment? If so that would allow the muffler bypass flap to be in the Loud position all of the time.

    With that said, the 997 engine does sound different being reved with no load (i.e. blipping the throttle with the car at a standstill in neutral) vs. under load and under acceleration. Part of the noise differential is due to the variable length intake manifold doing its thing under acceleration.

    My car essentially sounds muted at idle and just being reved, so I would not worry about it. Just get out there in the desert and have at it!

    Re: Sound differences

    See! I told you OE would know

    Re: Sound differences

    Yeah, im wondering though why it sounds quieter after risconnecting the PSE switch (one with the red tip) COMPARED to previously when it was still connected and in the on position ^^

    And yes, my car loves those long deserted desert roads ^^

    Re: Sound differences

    Quote:
    Flagg said:
    Yeah, im wondering though why it sounds quieter after risconnecting the PSE switch (one with the red tip) COMPARED to previously when it was still connected and in the on position ^^

    And yes, my car loves those long deserted desert roads ^^

    When you use the Porsche switch, PSE still has a quieter mode at certain rpm levels (I believe it's TUV mandated). When you unplug the electrical connector or the vacuum connector PSE no longer has the quieter mode. You're not the first to ask this - there's been a lot written about it - I'm sure you can find a more detailed answer in the archives - try search.

    Re: Sound differences

    Quote:
    Flagg said:
    Yeah, im wondering though why it sounds quieter after risconnecting the PSE switch (one with the red tip) COMPARED to previously when it was still connected and in the on position ^^

    And yes, my car loves those long deserted desert roads ^^




    The PSE bypass valves are either open or closed, so it cannot possibly sound different.
    Regardless how it's controlled.

    This is how the system works:

    The PSE valves are normally OPEN( spring activated) and are closed by the cars vacuum system .
    If you pay attention,everytime the car is started (just for the first second or so ) the PSE will always be loud .Until the vacuum builds up and closes the dampers.

    The vacuum to the dampers in turn is controlled by a 12 Volt operated electric solenoid valve .
    The solenoid is normally CLOSED and is OPENED by a 12 Volt signal. When it opens, it allows the vacuum to close the dampers .


    If the PSE is activated ( loud) per factory setting , at speeds up to ~ 50 mph .... whenever the throttle is used aggressively .....the solenoid gets a 12 volt signal from the cars computer and the dampers close ( PSE goes quiet ) and open again as soon as the throttle is relaxed.
    Above 50 mph the PSE dampers stay open .


    So, if you want the PSE to be always loud, just disconnect the 12 volt power to the solenoid ( orange plug) .
    The solenoid stays closed ,no vacuum to the dampers , and they stay open ( loud )

    Or, you can install a simple on-off switch into the 12 volt power wire going to the solenoid .
    That way you can control it from inside the car .
    With the switch closed, everything works per factory , and with the switch open , no power to the solenoid, PSE dampers stay OPEN (loud)
    I installed the switch in the ashtray .

    Re: PSE tech talk (not the usual q's!)

    Hey guys, i just got a 06 997tt, just wondering if the anyone know whether i can unplug the PSE just like the 997S??

    Thanks for the reply!


    Re: PSE tech talk (not the usual q's!)

    Hey, Flagg!  Nice to see yet another Rennteamer in Dubai!!  Regarding the louder noise when cold, that is because the car runs slightly richer and at a higher rpm (like the chokes of old cars) when first started.  It all calms down when the car is sufficiently warm and the ECU makes the mixture normal again.  This gets more pronounced with the free-flowing exhaust.  I noticed this immediately after I fitted an after-market exhaust in my Boxster.

    Hope you have (had?) a great time on the Autodrome - PCME has the BEST and SAFEST track day of all in Dubai.  But beware - its addictive!!


    Re: PSE tech talk (not the usual q's!)

    No such thing as a PSE for the 997TT, sorry.
    --
    2005 997S Blk/Blk

     
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