[The Nightman]

I ran a 330i exhaust on my 328i a while back and ended up swapping back to the stock exhaust as the cold starts and highway droning were annoying with the muffler valve always open. Otherwise, I enjoyed the sporty sound of the 330i exhaust and still find the stock exhaust to be too muted. So, I've been toying with the idea of manually controlling the valve in the 330i muffler so that the valve remains closed during cold starts and highway driving, and I can open the valve at other times. This is where I'm at so far:

1. The muffler valve is controlled by "vacuum control valve" (solenoid?) 18307604055. An OE Pierburg control valve is <$30 from FCP. It's also the same valve used on the N54 so it shouldn't be difficult to source. Basically, the valve has a two pin connector and the 12V is always live while the ground is switched by the DME. The valve opens when the circuit is complete (ie powered) and allows vacuum to close the muffler valve.

2. The vacuum source for the muffler valve is the plastic brake booster line (34336769622 on the 330i). The brake booster line has a tee and there is a vacuum line that runs from the engine bay to the trunk, where the solenoid is located. I'm not sure if I can directly swap the 330i brake booster line on, as the vacuum pump connection seems different from the 328i. I'm also not sure how I would splice the tee onto the 328i brake booster line as it is hard plastic. The N54 muffler valve control has the same set up.



3. Wiring would involve a 12v source to a switch, then to the control valve and to a ground point in the trunk. I believe I need a toggle switch or a switch that is normally closed, so that the control valve is energized and the muffler valve remains closed by default. Not sure what to use as a switch. There are exhaust toggle buttons on Aliexpress meant for other vehicles, but may look out of place:


https://www.aliexpress.com/item/1005003673887318.html

4. Where can I locate the switch? It's too bad all the factory buttons use a PCB board/module, otherwise it would've been cool to use a steering wheel button or add another button to the heated seat button row.

Just brainstorming ideas so far. Any input or suggestions are welcome!

[Lochstar8]

I have no input BUT I’m planning on doing basically the exact same thing. I’ve got a 330i muffler for my 323i as I found my “PE mod” drones WAY to much for my Liking. Similarly my car also dosent have the vacume lines running to the rear to actuate the valve. I’ve got a few ideas like adding an electronic vacume pump somewhere in the rear and just actuating that with a switch and or a relay and a wired/wirless remote. Or cutting off the vacume part of the vacume valve and mounting an electronic servo/motor of some form. Haven’t decided yet or made any full plans as it’s -30°C where I live so I will not be going outside anytime soon.

If I make anything work I’ll make an update.

[The Nightman]

Originally Posted by Lochstar8

I have no input BUT I’m planning on doing basically the exact same thing. I’ve got a 330i muffler for my 323i as I found my “PE mod” drones WAY to much for my Liking. Similarly my car also dosent have the vacume lines running to the rear to actuate the valve. I’ve got a few ideas like adding an electronic vacume pump somewhere in the rear and just actuating that with a switch and or a relay and a wired/wirless remote. Or cutting off the vacume part of the vacume valve and mounting an electronic servo/motor of some form. Haven’t decided yet or made any full plans as it’s -30°C where I live so I will not be going outside anytime soon.

If I make anything work I’ll make an update.

A separate switched 12V vacuum pump connected directly to the muffler tip valve is a good idea - simply turn the vacuum pump on whenever you want the valve to close. I don't know how much vacuum is needed to close the muffler tip valve though.

I did read that the muffler tip valve starts to rattle if it's closed all the time, so it might be better to have it normally open.

[Lochstar8]

Originally Posted by The Nightman

A separate switched 12V vacuum pump connected directly to the muffler tip valve is a good idea - simply turn the vacuum pump on whenever you want the valve to close. I don't know how much vacuum is needed to close the muffler tip valve though.

I did read that the muffler tip valve starts to rattle if it's closed all the time, so it might be better to have it normally open.

They actually make exhaust vacuum valve pump kits that just wire up and work for pretty much any exhaust. and if you get a nicer kit some even have a OBD2 port plugin that reads RPM and controls the valve accordingly depending on when you set it to open as well as wireless remotes. Now as for intagrating that into a factory switch or button around the dash area that may be a little harder than going the fully custom vacuum pump route.

As for the rattle yeah that’s definitely a problem but I think there is solutions out there. And fortunately for me the 330i muffler I found, I think was cut off the car like 50km after the car left the dealership it’s in perfect condition.

I will be installing my 330i mufffler this weekend but I’ll probably wait a while before going vacume actuated. But as I mentioned I’ll likely buy one of those boxes for the vacuum. Valvtronic actually sells one but it’s pretty much the same as all the Chinese ones but at 3x the cost ofc.

Here’s a link to the Valvetronic kit.

Image from a Reddit post by CatalinPCE of what those look like inside.