Muffler Delete - Valve Hose - Power Loss

[13M5F10]

Guys -

I had my bumper off yesterday and wanted to take the opportunity to show everyone how I plugged my hoses.

I used a hose plug which is the proper way to do it and just because I don't trust myself sometimes I added a hose clamp. This one is with a twist handle so I just twist to tighten rather than use a screw driver. Just preference. I believe stock hose is 5/16 so just buy a matching hose plug that fits a 5/16 hose. You can buy a kit with various sizes for just as cheap as a pair.

Everything you can buy from an auto store and it's less than $5.

Not plugging these will result in loss of power.

[MCarsFan]

Nice post.

[ChrisNich117]

I was told by my tech that the car uses an electric pump located in the rear for the vacuum system. I've never had any loss of power for either of my cars with the muffler delete and the tubes were simply disconnected and tucked away. Has anyone actually seen where these tubes lead to?

[ur20v]

I agree - these exhaust valves use vacuum not boost to operate, there will be a vacuum circuit with a vacuum reservoir and either a pump or vacuum generator.

You should still blank them as you are causing aleak which could effect other items including the boost control valves on if a seprate circuit the turbos on pre LCI cars or just make a pump constanstly run.

[ur20v]

Found this:

The valve is part of the BMW Active Exhaust and is purely for noise reduction.
It is operated by a vacuum pump underneath the trunk (a common mod on the E90s is
to disconnect the pump via the electric connector in the trunk to keep the valve open).

The basic system was initially introduced on the E46 platform and the electrical function
of the exhaust flap operation is controlled by the MS 41.1 module.
Where at idle speeds, up to 2500 RPM: the exhaust flap is closed with vacuum applied to the actuator. This causes the exhaust gas to pass through the long resonator pipe, reducing the low frequency noise that is generated.

On the F10 it is now reverse where vacuum applied means the exhaust flap is opening
There is no button/setting which will keep the valve permanent open ,the only option is to
"hard wire" the valve in the open position and seal/plug the vacuum line.

[ur20v]

Also the engine has its own vacuum pump on the crank case:

This vacuum pump bolts to the timing case and is driven off of a small sprocket. Although capable of functioning for many years, the vacuum pump will eventually require replacement for continued operation of your engine.
If you have stated to notice noise coming from the vacuum pump on your engine, or have noticed that some of the vacuum powered systems are not functioning properly, it may be time to replace your vacuum pump.
This pump should be replaced at the earliest symptoms of failure, as once the pump fails completely, it can drop metallic components, such as bearings, into the timing case leading to complete engine failure.

https://www.ecstuning.com/BMW-F10-M5...tem/ES2711870/

[13M5F10]

Originally Posted by ur20v

I agree - these exhaust valves use vacuum not boost to operate, there will be a vacuum circuit with a vacuum reservoir and either a pump or vacuum generator.

You should still blank them as you are causing aleak which could effect other items including the boost control valves on if a seprate circuit the turbos on pre LCI cars or just make a pump constanstly run.

Thanks - I took it out.

[13M5F10]

Originally Posted by ChrisNich117

I was told by my tech that the car uses an electric pump located in the rear for the vacuum system. I've never had any loss of power for either of my cars with the muffler delete and the tubes were simply disconnected and tucked away. Has anyone actually seen where these tubes lead to?

They lead to a vacuum pump in the trunk.

This isn't something new, it's a known issue amongst the F10 M5 that when you disconnect these hoses and do not plug them, you will have a loss in power due to a leak of some sort. I thought it was boost operated but I may be wrong, could be part of a larger system. Anyhow, you will feel like you have no boost when ridin with these open.

[ChrisNich117]

Originally Posted by 13M5F10

They lead to a vacuum pump in the trunk.

This isn't something new, it's a known issue amongst the F10 M5 that when you disconnect these hoses and do not plug them, you will have a loss in power due to a leak of some sort. I thought it was boost operated but I may be wrong, could be part of a larger system. Anyhow, you will feel like you have no boost when ridin with these open.

It's purely psychological

The power is there, we've just been too spoiled by how much power these cars make!


Here is a nice read. You'll see that these tubes do not connect to anything related to the turbos.

http://m5carblog.blogspot.com/2013/0...urbos.html?m=1

[13M5F10]

Originally Posted by ChrisNich117

It's purely psychological

The power is there, we've just been too spoiled by how much power these cars make!

I wish that was the case.

There's a clear loss in power with these not plugged in. I've personally tried it plugged and unplugged.

Google it and see the countless complaints about the issue.

[ChrisNich117]

Originally Posted by 13M5F10

I wish that was the case.

There's a clear loss in power with these not plugged in. I've personally tried it plugged and unplugged.

Google it and see the countless complaints about the issue.

I just posted the link above, check that out.

[13M5F10]

Originally Posted by ChrisNich117

I just posted the link above, check that out.

I agree they aren't connected to the turbos. I corrected that. I misunderstood how these operated. Still doesn't change the fact that you have power loss when these are not plugged. It's been proven already.

[ChrisNich117]

Originally Posted by 13M5F10

I agree they aren't connected to the turbos. I corrected that. I misunderstood how these operated. Still doesn't change the fact that you have power loss when these are not plugged. It's been proven already.

I've never had it happen. I'm not saying you're wrong, I just have no idea how you could lose power when they are not part of the same system. I'd be interested to know how the two systems communicate with one another.

[13M5F10]

Originally Posted by ChrisNich117

I've never had it happen. I'm not saying you're wrong, I just have no idea how you could lose power when they are not part of the same system. I'd be interested to know how the two systems communicate with one another.

I'm interested too... When i tested it, there was huge pressure loss. Felt like boost wasn't kicking in and lagged badly.

[Rockin-The-F10]

Hmmmm well I had my exhaust done about a week ago and of course they didn't plug the lines... After reading this thread I went out and plugged them.
I really find it hard to believe it will affect the power but if you guys say so then I believe ya. lol.

Either way I went out and plugged the lines... lets see what the difference is in the morning.
I will let you guys know what the results are.

[MCarsFan]

Originally Posted by 13M5F10

I'm interested too... When i tested it, there was huge pressure loss. Felt like boost wasn't kicking in and lagged badly.

I'm telling you that @13M5F10 is speaking from experience about this topic as am I.


13M5F10 noticed big power loss when his Turner exhaust was on his car without the lines blocked.

When I fit my straight piped GTM exhaust, Eloy who designed the exhaust specifically told me to ensure the lines were blocked off. This is coming from the guy who built this exhaust.

[DCT OFF]

My local BMW dealership installed a full eisenmann race exhaust system on my M5,the tech told me it's important to plugged the hose to prevent loss of power.

[Rockin-The-F10]

So I plugged my lines last night.. went out for a drive today.

Well I have to say....
I think there was actually a gain in power after plugging the lines. Not sure how or why this is possible, but I would say that there was definitely a return of power.
If your exhaust doesn't utilize the vac line... definitely make sure you plug them up.

[djseto]

Can you just connect it back to the valves or should it be plugged shut?

[13M5F10]

Originally Posted by djseto

Can you just connect it back to the valves or should it be plugged shut?

Those hoses can be reused for sure but not sure you can plug them if the valves are no longer there hence the need to plug them from leaking.

[Lerxst M4]

Yup, my AWE Touring exhaust also came with plugs for the lines to be blocked off as well.

Only an axleback so not looking for a performance increase but I certainly didn't want to experience any DECREASE so I ensured they were plugged.

[djseto]

I plugged mine and sure as $hit the car felt better. Maybe it's psychological, but I still want to see some dyno runs or some engineering explanation to make sure my brain isn't just tricking me....