650i dual m exhaust but left side works??

[MBMW]

I just installed the M performance mufflers on my 650i sound is good but wish it was a little louder. However I noticed that when I rev the engine the sound is coming out of driver's side only.

This is a V8 engine so unless there is a valve in the central muffler it should come out of both sides right?

650 owners can you please confirm if this is normal?

[Duff Ace]

That is not right. So are you saying the exhaust is not flowing on one side?

Did you do the install yourself? If so, and you just installed the mufflers axel back then there is something wrong with the mufflers. There are valves that open above a certain rpm (unless you use the zip tie method or remote controlled)

My advice would be take it to an exhaust shop

[MBMW]

The mufflers were installed by a BMW specialist I checked the install when the car was on the lift it looked fine on both sides.

Checked the part numbers they are correct according to real oem

Gases are coming out of both sides but the burble and grunt is coming out of the left side only. That tells me there is not enough pressure on the right side.

Just did a cold start, again steam was coming out of both sides but only the left side was giving the sport note.

[gmusquiz]

Originally Posted by MBMW

The mufflers were installed by a BMW specialist I checked the install when the car was on the lift it looked fine on both sides.

Checked the part numbers they are correct according to real oem

Gases are coming out of both sides but the burble and grunt is coming out of the left side only. That tells me there is not enough pressure on the right side.

Just did a cold start, again steam was coming out of both sides but only the left side was giving the sport note.

If the exhaust gases are coming out, then it is open to that side. Do you think it's just the valve not opening and maybe a problem with that vacuum line feeding the actuator arm or something? Or a stuck arm? Have you tried opening the valve manually with the car off?

[MBMW]

Tried that same issue the sound is coming from one side went to the dealer to check and realized that this is normal at idle only one turbo works second spools when the engine is under load. BS? Maybe but I rechecked everything all is correct no leakage in the right exhaust

[Flying Ace]

Originally Posted by MBMW

Tried that same issue the sound is coming from one side went to the dealer to check and realized that this is normal at idle only one turbo works second spools when the engine is under load. BS? Maybe but I rechecked everything all is correct no leakage in the right exhaust

this is correct. There's a vacuum that then allows additional exhaust gas to exit the 2nd muffler when there is more load.


This is also same reason why your exhaust flaps are closed at idle.