Exhaust valves open/closed

[Simpo Two]

My journey continues...

At Helmingham this year I spied a lovely green DB9 Volante and took a couple of photos. I see that the left side of the steering column features a rotating knob marked 'Exhaust valves - open - closed'.

Is this a common mod?

Edited by Simpo Two on Saturday 9th October 23:01

[bogie]

Yep fairly common in various forms. Some owners may hard wire knobs/switches, others (including myself) have remote control kits on the circuit controls the exhaust valves so you can manually open or close them.

The valves help keep the noise down to get the cars through type approval, then at 4k revs you get the full sound. You can switch this so that they are "loud" from tickover.

[acole]

To clarify, this is a valve located in the muffler of the exhaust to change the exhaust note, not the exhaust valves in the engine. Search 'Fuse 22' to see all of the discussions on it.

[Simpo Two]

Thanks - this was prompted because when I started the DB9 I was surprised how quiet the exhaust was, much quieter than my standard XK 4.2.

When I got it out on a clear stretch of road, dropped a cog and gave it a shove then 'RARP!' the exhaust valves opened. But there was nothing between 'very quiet' and 'RARP!'. I know XKs are different machines but they do at least give you some audio interest on start up.

So - pulling the fuse makes it loud all the time, and the switch (hardwired or remote) gives you manual control of on/off. I wonder if the valve/flap jobbie can be modified a bit so it's slightly open when in the closed position?

I need to have the car and live with it a bit before deciding what to do, if anything, but this is all useful feedback, many thanks.

[bogie]

Yes you could modify the valve...or choose a different exhaust back box. There are 2 valves so 1 valve open all the time gives a bit more volume. I have 1 valve open all the time just because its stuck

Also note when you test drove the car likely it was warm. On a daily basis when you start the car yourself it will be on the cold start cycle and more noisy with valves open for a while until its warmed up. If you want to make an early get away without waking the street, some aftermarket valve switches provide a "fully closed" position. This is useful if you have an extra noisy back box on and want to keep it quieter until you get out of town etc.

..there are so many customisable options on exhaust, link pipes, cats etc

[Dewi 2]

Simpo Two said:

... I know XKs are different machines but they do at least give you some audio interest on start up.

So - pulling the fuse makes it loud all the time, and the switch (hardwired or remote) gives you manual control of on/off. I wonder if the valve/flap jobbie can be modified a bit so it's slightly open when in the closed position?

As alresdy mentioned, the valves will be open up to about 1,500 rpm on cold start up.
You discovered that the full orchestra occurs when accelerating. Probably an arrangement which suits most owners, because it does have the benefit of providing quiet motorway cruising (steady throttle).

Swapping to an after-market back box, can sometimes result in changing the sound from true Aston Martin. If you just want an increased sound level, then reducing the cat. cell count is the way to go. Being less restrictive, it also slightly increases power.

If you should sometimes want quiet all the time, then a wired switch is required, because the remote system effectively either removes or replaces the exhaust fuse to give either OEM or 'Open all the time'.

[Simpo Two]

bogie said:

Yes you could modify the valve...or choose a different exhaust back box. There are 2 valves so 1 valve open all the time gives a bit more volume. I have 1 valve open all the time just because its stuck

Also note when you test drove the car likely it was warm. On a daily basis when you start the car yourself it will be on the cold start cycle and more noisy with valves open for a while until its warmed up.

Aha bingo - the car was indeed warm when I arrived to see it. That made me a bit suspicious - what rattles was it hiding? - but the dealer said he'd been moving it about for valeting.

Dewi 2 said:

Swapping to an after-market back box, can sometimes result in changing the sound from true Aston Martin. If you just want an increased sound level, then reducing the cat. cell count is the way to go. Being less restrictive, it also slightly increases power.

If you should sometimes want quiet all the time, then a wired switch is required, because the remote system effectively either removes or replaces the exhaust fuse to give either OEM or 'Open all the time'.

Interesting, many thanks. I always like to try to understand what's going on!

[cadman]

i have the cc charger remote exhaust valve control.but after installing headers and 200 cats i found the exhaust
way too loud in the loud mode for my old ears, and having the engine remapped for those mods i had the exhaust valves
programmed in the tune to be in quiet mode all the time.the valves get signal from the ecu to activate a vacuum pump to open and close at a certain rpm.they can be programmed to activate at any rpm or not at all.but i still have the option for loud with the cc remote.

[Francis2002]

I'm replying to an old post but maybe someone will read this. I just went to the DTC here in Switzerland, the noise police.

I was looking for a certification of good behavior! In order to register an American spec car in Switzerland, you must pass this test. At $1 000.- the visit, it is specifically bitter to fail it... which I did...

On idle it should make no more than 74 decibels. My car was at 81... at 4500 rpm the max should be 84 decibels, my car was at 94...

The technician did say my exhaust valves were open the whole time.

First, how do I fix this issue, and it's not fuse 22 related. Maybe the relay?

Second does anyone have the manufacturer's decibel chart to see if this American spec car would pass this test if the valves were closed.

Now van it be programmed somehow to meet those noise guidelines?

Thanks for your input,
Francis

[Simpo Two]

Francis2002 said:

On idle it should make no more than 74 decibels. My car was at 81... at 4500 rpm the max should be 84 decibels, my car was at 94...

The technician did say my exhaust valves were open the whole time.

Hi Francis - according to Aston1936 the valves open above 3,000rpm - so it sounds like you need something to keep them closed at all rpm. Hopefully someone will tell you how to do this; I guess it depends on what the default position is - ie whether it needs input to open them or close them.

[Gary C]

Francis2002 said:

On idle it should make no more than 74 decibels. My car was at 81... at 4500 rpm the max should be 84 decibels, my car was at 94...

Thanks for your input,
Francis

So twice as perceptively loud as permitted ?

(assuming db(a))

[LTP]

[quote=Francis2002The technician did say my exhaust valves were open the whole time.

First, how do I fix this issue, and it's not fuse 22 related. Maybe the relay?

Francis
[/quote]
The first thing to check is that fuses 15 and 22 are in and not blown. The fuse that controls the valves is different depending on the year, and you didn't say what year your car is.

Secondly, having established that the fuses are present and intact (which from your post you may already have done) is to check if the valves are actually moving - you can do this by watching them from under the car as someone starts the car - they should cycle on start-up, then close, then open as the revs pass the threshold. These valves have been known to stick, and can often be freed up by working the actuator lever and applying release agent to the pivots. They have been reported to seize to the point where replacements are required; AML will tell you a new backbox is required, but I believe you can buy just the valves from alternative sources, then get them welded in.

Thirdly, you could try swapping out the appropriate relay for an identical neighbour in the fusebox.

Finally, check if the vacuum pipes are attached to the actuators and don't have leaks - some people, wanting the "permanently open" sound, have been known to disconnect the pipes from the actuators and block the ends.

[Wafu7]

LTP said:

These valves have been known to stick, and can often be freed up by working the actuator lever and applying release agent to the pivots. They have been reported to seize to the point where replacements are required; AML will tell you a new backbox is required, but I believe you can buy just the valves from alternative sources, then get them welded in.

If it’s a case of seized valves, you can source replacements at David Appleby Engineering:

https://www.davidapplebyengineering.com/shop/produ...

[Simpo Two]

LTP said:

Finally, check if the vacuum pipes are attached to the actuators and don't have leaks - some people, wanting the "permanently open" sound, have been known to disconnect the pipes from the actuators and block the ends.

Ah that's interesting, so it's vacuum operated and no vacuum = open. But even so he needs them closed at 4,500rpm when they'd normally be open.

[DB9S Paul]

Hi Francis,

I've replied to your comment on my website too.

The Valves are open by default at idle (up to 1500 rpm) and above 3500rpm so even if your valves were operating correctly it would fail the tests.

I would check that fuse 22 is in place and then that the valves aren't seized, if they are try loosening them with penetrating oil and some gentle persuasion.

You would then need to add a switch to enable them to be closed permanently at will, instruction for which are on my website, below

https://db9s.com/aston-martin-3-way-switchable-exh...

[KernowShep]

This thread might help/be of interest - ("3-way exhaust switch") - https://www.pistonheads.com/gassing/topic.asp?h=0&...
I expect there will be others using similar search wording.

[LTP]

Simpo Two said:

Ah that's interesting, so it's vacuum operated and no vacuum = open. But even so he needs them closed at 4,500rpm when they'd normally be open.

I think AML used to sell the Vantage into Switzerland and, AFAIK, the exhaust systems were common across Europe. I wonder if someone has modified OP's car away from standard?

[Davil]

LTP said:

I think AML used to sell the Vantage into Switzerland and, AFAIK, the exhaust systems were common across Europe. I wonder if someone has modified OP's car away from standard?

That’s what I was thinking. Especially a US car as they are probably the biggest modders of exhaust.

[DB9S Paul]

Worth checking if the secondary cats have been removed, they make it much louder.