PSE with cold engine

[thormann]

Hi,

I have a factory installed PSE in my 2004 C4S.

If I go to work early in the morning, I want to start the engine in quite mode and therefore turn on the electrics, switch the rocker switch to quite mode and then only start the engine.

However, it takes some time (about 30 seconds) of driving until the sound becomes silent. Also if I leave it in the loud mode it is much noisier in the first 30 seconds.

Is that normal? I understand, that the rocker switch (via the control relay) controls valves to pneumatically open and cloose the mufflers.

Any hint appreciated.

Thanks, Gert

P.S. I have disconnected the speed signal from the relay

Edited June 23, 2008 by thormann

[Loren]

The valves are switched via electrical solenoids but the valves are moved by engine vacuum.

Usually engine vacuum comes up pretty quick after the engine is started.

[RFM]

As long the secondary air pump runs, the PSE is louder ( more an other sound )

[Kim]

The vacuum chamber retains more than enough vacuum overnight to enable to me to switch to quiet prior to starting in the early morning hours.

[RedRidge]

you may have a vacuum leak! Might need a new check valve before the vacuum tank, or a leak after the tank... some people choose not to use the check valve that comes with the kit. This check valve will keep vacuum in the tank for a long time. Ive had vacuum as long as 2 weeks and can switch to quiet mode before starting the engine.

[thormann]

Thanks for all the answers.

@RFM

Yes, it is louder and a different sound. But it is more a crackle sound than a howling sound. Can this really be the air pump? Or is this a result of the additional

air, that makes the engine sounding like this?

With my Durametric I could activate the air pump to see, if the sound comes from there. Can I do this without problems with engine running? Or can this be dangerous for the engine under certain conditions?

How can I check, if the vacuum system is leaking and where?

Thanks again, Gert

Edited June 24, 2008 by thormann

[Kim]

How can I check, if the vacuum system is leaking and where?

If you do a search for PSE installation help, you will find many labeled pictures of the various parts.

In the picture below, the vacuum tank is slightly to the right, and toward the front of the car from the item labeled "switch". Follow the rubber tubing from your electrically operated vacuum switch back to the tank. That is where leaks may occur, or where a check valve may be missing / malfunctioning.

The whole purpose of this tank, as far as I know, is to retain vacuum so that you may switch the PSE prior to engine start.

[RFM]

The additional air is the cause of the difference in sound, you can activate the air pump with the engine running without problems. The vacuum system leak test can be performed as Kim mentioned.

[thormann]

If the additional air changes the sound so much in cold condition, I am thinking now, this has me made thinking, the PSE didn´t close prior to start. Can I somehow check if the PSE closes without starting the engine?

[RFM]

PSE is always open ( loud ), the system needs vacuum to close ( quiet )

[thormann]

Yes, but the vacuum shall be stored in a tank. So I should be able to close the PSE without the engine (and air pump) running as long as the vacuum system is tight. If not, I have to look for leakages as per above. Or am I wrong?

Edited June 25, 2008 by thormann

[Loren]

I don't think the vacuum in the tank is stored long when the engine is not running.

[ssp996]

I read somewhere that the PSE valve is also spring-loaded which is what keeps the valve in the default open mode unless the switch is activated which in turn uses vaccum to force it closed.. On mine, if I want to start on quiet mode, I can activate the dash switch before I crank the engine. It will have enough vaccum reserve to do that. I can even hear the valves move.

[Kim]

I don't think the vacuum in the tank is stored long when the engine is not running.

Loren,

While I have done no definitive testing (and am on vacation now, so I cannot) .... it is routine for me to use the dash switch to quiet the PSE first thing in the morning .... when my car has been sitting in the garage for at least 2 days, maybe more. As I said, no testing of this precise premise .... but I've never had it NOT work that way with retained vacuum.

[Loren]

Impressive - most cars won't hold a vacuum overnight.

[RedRidge]

the check valve (before the vacuum tank) and the SV (after the vacuum tank) holds the vacuum pretty good. Mine holds vacuum easily a week and still closes the valve before start-up.

[Kim]

Mine holds vacuum easily a week and still closes the valve before start-up.

OK, now I have done a more definitive test. Parked car on June 12 and went on vacation.

Started it up again for the first time on June 29. Before starting, switched the PSE to quiet, and there was plenty of vacuum to do the job.