E60 Muffler Flap Open Mod
 

If your E60 exhaust muffler has a flap or butterfly valve (used for low engine speed noise suppression), this mod shows you show to keep the muffler flap open whenever the engine is running. This results in a louder exhaust note during low or normal engine speeds. Some drivers may prefer a louder than stock exhaust note, especially for manual transmissions.

Part required:
- Two-inlet vacuum host connector, with 3.9 mm or 5/32-inch inlets.
http://farm8.staticflickr.com/7433/8...59162487_n.jpg

Procedure:

• Work when warm, so that rubber vacuum hoses are softer and more pliable.
• Access the left tail light assembly located under a trunk felt liner, held by two black plastic thumb screws.
• Locate the electrical controller for the muffler flap inside the trunk, under the left tail light assembly.
• Note the inlets and the connected hoses, in case one wishes to undo this modification (one hose goes into trunk floor, other hose route towards vehicle front).
• Firmly and carefully remove the vacuum hoses from the electrical controller, taking care not to cut your hand on the many sharp edges around the work area.
• Connect the removed hoses together with the vacuum hose connector.

Start your engine. The exhaust note should sound louder than before and exhaust pressure is felt at both outlets, instead of just at the outboard outlet. Turn off engine. Modification is complete. Button up the trunk.

http://farm4.staticflickr.com/3736/8...889192aa_b.jpg

Modified muffler flap operation:
- Engine on, vacuum is created, muffler flap open
- Engine off, no vacuum, muffler flap shut

As noted, this modification is easily undone, should one prefer to return to stock muffler operation.

List of E6x 5-series with electrical controller for the muffler flap:
E60:
E60 545i Sedan, USA
E60 550i Sedan, USA
E60 520d Sedan, Europe
E60 530d Sedan, Europe
E60 525d Sedan, Europe
E60 M5 Sedan, Europe
E60 535d Sedan, Europe
E60 530xd Sedan, Europe
E60 545i Sedan, Europe
E60 540i Sedan, Europe
E60 550i Sedan, Europe

E60N (LCI):
E60N 550i Sedan, USA
E60N 535i Sedan, USA
E60N 535xi Sedan, USA
E60N 520d Sedan, Europe
E60N 530d Sedan, Europe
E60N 530xd Sedan, Europe
E60N 535d Sedan, Europe
E60N 540i Sedan, Europe
E60N 550i Sedan, Europe
E60N 525d Sedan, Europe
E60N 525xd Sedan, Europe

E61:
E61 530xi Touring, USA
E61 520d Touring, Europe
E61 530d Touring, Europe
E61 525d Touring, Europe
E61 535d Touring, Europe
E61 530xd Touring, Europe
E61 545i Touring, Europe
E61 530i Touring, Europe
E61 530xi Touring, Europe
E61 550i Touring, Europe

E61N (LCI):
E61N 535xi Touring, USA
E61N 520d Touring, Europe
E61N M5 Touring, Europe
E61N 530d Touring, Europe
E61N 530xd Touring, Europe
E61N 535d Touring, Europe
E61N 530i Touring, Europe
E61N 530xi Touring, Europe
E61N 550i Touring, Europe
E61N 525d Touring, Europe
E61N 525xd Touring, Europe

nice write-up!

Sounds awesome (and easy). Two questions:
1) Where did you get the hose connector?
2) This may sound naive, but is exhaust running through that hose? If it was, obviously you'd have to be careful to not have a leak, lest you pump fumes into your cabin.

The connector was from an automotive part store, specifically Autozone.

The hose is part of the engine vacuum, which remains intact in this mod. The hose terminates at the muffler flap controller, outside the muffler, it does not route any exhaust - if it does, it should remain in the vacuum system.

My highway engine speeds is around 2500 rpm. The muffler flap is normally closed. Other parts of the country with faster flowing traffic would see engine speeds higher than 3000 rpm where the flap opens.

Will this work on a 525i?

Did this today. Seems to increase low resonance sounds at idle, though I couldn't notice a difference while driving around town. I'm going to keep it intact for a few weeks and evaluate.

Thanks for the write up vkhong!

i don't have it this in rear boot, is 525d lci, these enginee have this?

In my original post, I added a list of what RealOEM shows for E6x 5-series with the electrical controller for the muffler flap.

In this image, the muffler flap is visible on the right / inboard exhaust outlet:
http://i.ebayimg.com/t/BMW-Alpina-E6...n5g~~60_12.JPG

Vehicles with the muffler flap will have cleaner inboard tailpipe versus outboard tailpipe.

Is this the connector to order from autozone?
Dorman/AutoGrade 6 pcs. hard L vacuum tubing connector assortment (47355) | Vacuum Connector and Tubing | AutoZone.com

for diesel only is 535...:(