vanHunks

I noticed on my recently acquired 2011 Carrera GTS (about 30k miles) that the vacuum lines to the exhaust valves were hanging loose and not capped. I presumed the previous owner had pulled them off and was annoyed that the OPC where I bought the car had not noticed this. I pushed them back on and all was restored. When I raised the matter with OPC I was told it was common for the lines to slip off on their own. I'm sceptical but am curious if other people have experienced this. Am concerned about the road debris now in the vacuum system.

phaphaphooey

The EXACT same thing happened to me essentially. I purchased a low mile 2009 C2S (14k miles) a few months ago. Although it had PSE the exhaust was stuck "open" regardless of the button. I thought I either had an electrical fault or a vacuum leak but all looked good in the engine bay as far as the vacuum lines were concerned. I pulled the rear bumper recently to replace the center muffler with bypass pipes (which I would highly recommend that you do FWIW) and found that the vacuum line leading to the passenger side muffler had slipped off the nipple protruding from the valve on the muffler. There was even a worm clamp on both lines at the mufflers but apparently the worm clamp on the passenger side was not tight enough. I put the line back on the passenger side muffler and tightened the heck out of it. I also tightened the driver's side a little bit for good measure even though it has stayed on. This fixed the PSE and all functions as it should now. Like you, I am concerned about what my engine ingested through that open vacuum line.

Petza914

Your engine wouldn't have ingested anything. Vacuum to the PSE valves is supplied byva little electrically actuated vacuum solenoid and that's where the hoses connect, not to the engine itself. When I was doing my rear bumper upgrade, I changed the plumbing for the system from the rubber lines to plastic lined Russell braided stainless lines. I now have 1 line coming from the vacuum solenoid to a threaded metal T that's located in the wall between the engine compartment and the space under the rear bumper. From the arms of the T, one braided stainless line runs to each muffler solenoid, I heated the ends to slightly soften the inside Teflon, then when warm, pushed them on to the vacuum valve nipples and then clamped them with small ferruled hose clamps. Been on there without a single issue for 4 years now, and they look nice through the side slots in the rear bumper.

Not going to the extreme like I did, a slight upgrade might be to replace your rubber lines with some silicone versions.


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vanHunks

Gentlemen,

Thanks for the feedback - will try some new clips. Am glad to hear there's unlikely to be any damage. Have been thinking about a centre muffler bypass but the car's under a Porsche Used Warranty for the next two years and the local OPC's a bit sniffy about private mods - even something as innocuous as an exhaust change.

StormRune

It sounds like you are missing the clamps. Porsche part #999.512.361.02. You can get them for around $7.50 each. Getting in there to tighten them is a little tricky but can be done once you rotate them to the right angle. Here are some photos/images. If you don't see these on your car then that probably explains it:

vanHunks

Thanks, the clamps were definitely not on the lines, reinforcing my view that someone removed them and the story about them slipping off on their own is nonsense. I saw Matt Moreman's clip (one of a strangely addictive set !) about removing the lines and he had to put plenty of muscle into it. Anyway, will let the OPC sort this out, they should have done before I took the car.

extanker

road debris in the vacuum system.......i will have to share this beauty ....my wag....the OPC is falling on the ground laughing

vanHunks

I'm glad I can lighten your day and that of your OPC but am curious to know the source of the humour - common sense suggests the unplugged pipes would suck in dust and water-spray thrown up into their vicinity; over a long period this would damage or at least block the system. If this is not the case then I'm happy to be enlightened.

Petza914

Unless you unplug the electrical connector from the vacuum solenoid, the car will create a vacuum to the end of those lines that should be on attached to the muffler vacuum valves and they will ingest crud effecting the system performance or making it inoperable. Those lines are very small inside diameter and it won't take much to clog them up.

StormRune

I totally agree with vanHunks and Petza that an open vacuum line will eventually suck in dirty water with oil, grease, and fine particles from the road and is very undesirable. It also creates a small vacuum leak which isn't ideal for engine performance, especially at idle when a little unexpected air behind a nearly-closed throttle body can throw the ECU off a bit. As Petza points out, the bulk of the vacuum line run to the PSE is a much more narrow tubing than you see in the last few inches as it connects to the mufflers or the solenoid. It only has a 1mm opening inside of 4mm hard plastic tubing. It would be very easy to clog.

As Petza observed, unplugging the connector closes the vacuum switch in the solenoid, leaving the PSE on all of the time since open (louder) is the default position of the vacuum valves on the muffler.

Petza914

Yup. One small point - none of the vacuum for the PSE system is derived from engine vacuum, so no effect at all on the ECU - it all comes from the electric vacuum solenoid.

StormRune

How about that Petza, you taught me something again... but it requires a partial correction to your small point:

Based on further investigation, it turns out that the vacuum in our cars comes from the secondary air pump (maybe that is what you meant, but just for clarity that is a better name). It is electrically driven and requires a 40 amp fuse, implying it is a heavy draw when it is running. It tends to run for a bit when the car first starts to pump extra air into the engine and along with an extra rich fuel mix during the first many seconds after startup to heat the catalysts more quickly, giving us that extra growl we often hear for the first 30 seconds or so. On the flip side, it also generates the vacuum used for all of the vacuum-driven things like the PSE valves and at the same time "stores" some vacuum in a vacuum reservoir. When the vacuum in the system runs low, the pump runs again.

Now it seems that if you leave a vacuum line unplugged, you are not only pulling in moisture and fine crap, you are also causing the secondary air pump to run nearly continuously. A 40 amp draw on the engine will result in lost power due to the extra alternator load, plus you will wear out the pump a lot sooner... and it costs over $500.

In other words, make sure to keep those vacuum lines connected or plugged! And as Petza points out, it won't have any effect on smooth running due to air leaking into the manifold (like in much older cars), but it will have some effect on power and especially your budget at some point.