[Paddy]

I notice that the leftmost of the 2 chrome exhaust tips on my 330i E90 is quite black (sooty) while the one on the right has hardly any blach on it at all. Does anyone think this might be a problem. I expected them to blacken somewhat but more evenly.

[aranjha]

no its not the right one has a flap that only switches at certain speeds from what i understand. theres a thread on this somewhere

[ben1364]

One is closed at low rpm to enhance torque delivery.

[Paddy]

Thanks guys, I'm amazed how I keep learning new stuff about this car.
Did a search as advised and found details.

[siriusinvestor]

Originally Posted by ben1364

One is closed at low rpm to enhance torque delivery.

I have an eisenmann racing exhaust installed on my e90, does that mean I lose some of my torque at lower rpms, since the eisenmann does not have the flap at the right exhaust?

[Atty]

Interesting. I've noticed black soot too. It's hard to get off and looks really crappy. Never had it in my E46...

[e90driver]

I added the chrome tips to my 325 and they always get black. Eagle One brand has a product called "wadding". It's in a silver metal container- it's like a rough cotton moistened with some solution. Remove a peice and rub all of the black off (it will take a few minutes and some elbow grease if it hasn't been done in a couple months) then buff to a shine with a clean cloth. The product is like $4 and will do your exhaust trim for probably 1/2 of the life of the car or more.

[E90Fleet]

Originally Posted by ben1364

One is closed at low rpm to enhance torque delivery.

Official BMW word is it has no effect on torque, only sound

[e90driver]

e90fleet- is this system present in the us 325i as well?

[E90Fleet]

Originally Posted by siriusinvestor

I have an eisenmann racing exhaust installed on my e90, does that mean I lose some of my torque at lower rpms, since the eisenmann does not have the flap at the right exhaust?

No effect

[E90Fleet]

Originally Posted by e90driver

e90fleet- is this system present in the us 325i as well?

No

[ben1364]

Originally Posted by E90Fleet

Official BMW word is it has no effect on torque, only sound

###
Looks like there is conflicting word going around and I don't know which is correct. I do know that 4 valve dohc engines suck a lot of air and I was told by a senior tech who has participated in numerous BMW NA training sessions that low end torque is what prompted the valve. Who knows...

[E90Fleet]

Originally Posted by ben1364

###
Looks like there is conflicting word going around and I don't know which is correct. I do know that 4 valve dohc engines suck a lot of air and I was told by a senior tech who has participated in numerous BMW NA training sessions that low end torque is what prompted the valve. Who knows...

Well both the E46 and E90 training manuals say its for sound only and the BMW E46 and Schnitzer E46 and E90 sport exhausts dont have it, yet help create more torque than original exhaust. ( the BMW one im talking about is not what comes with the sport package, but a optional sports exhaust available in europe )

[E90Fleet]

Here is a online explanation of it on the E46

" That is called the Active Exhaust System Actuator (AESA). The AESA consists of the following:

Exhaust flap with vacuum actuator
Solenoid actuator valve
Vacuum reservoir with check valve
MS 41.1 control module
The electrical function of the exhaust flap operation is controlled by the MS 41.1 module.

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.

Above 2500 RPM: the exhaust flap opens. This allows the exhaust to pass through the short pipe which maximizes the back pressure effect to provide the best performance.

In the event of electrical or vacuum failure the flap will rest in the open position providing maximum exhaust throughput."

[ben1364]

E90Fleet said in part, "Here is a online explanation of it on the E46 <snip> That is called the Active Exhaust System Actuator (AESA). The AESA consists of the following:

Exhaust flap with vacuum actuator
Solenoid actuator valve
Vacuum reservoir with check valve
MS 41.1 control module
The electrical function of the exhaust flap operation is controlled by the MS 41.1 module.

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.

Above 2500 RPM: the exhaust flap opens. This allows the exhaust to pass through the short pipe which maximizes the back pressure effect to provide the best performance.

In the event of electrical or vacuum failure the flap will rest in the open position providing maximum exhaust throughput."
###
I would think the strtegy would be similar for the E 46 and the E 90 engines but who knows. It is somewhat confusing, huh?

[voltron1011]

I would think it has something to do with Valvetronic. Since the system is now continuously adjusting how far the valves open and close (from almost nothing @ idle, to completely opening @ full throttle), there is no need to have a device further down the exhaust system doing the same thing.