[horsepower_and_hounds]

So when I installed the MPE I did the "flap open" unplug mod and it really didn't due much for me. I felt some resonating in the lower rev numbers and figured that the German engineers must know best so I plugged it back in.

Since then I have read a lot of posts, articles and debates on how it functions, reasons for it and the so called advantages/disadvantages. Some even think that it is a "active" flap and opens/closes while driving based on load, rpm's and blah blah blah. Bottom line I am not sure anybody really knows and I am damn confused.

Now i have added an new variable...the Stage 1 tune box. So with the increased output and flow thru the exhaust do you guys think the flap mod should be done again...I am not sure that any advantages of having it operated (if it really is) by the computer still exist...those tuning parameters will be all thrown off due to the tune.

Anyway I was just sitting her pondering it and thought i would burn up some typing time

Opinions?

[mike@x-ph.com]

With the price of stage 1 + BMS flap you can just get the JB4 ( which gives you more power + the Flap open / close feature)

[kd0t]

Mike, where can you choose to open/close the flap in JB4 software?

[chaddy74]

you cant simple !! The flap is an active flap its not just for cold start its opening and closing all the time, !! Its supports low end torque in certain driving conditions . I have a full aftermarket exhaust and high flow DP catted !! I welded the flap back into the high flowing muffler exit point. Works for me !!

Originally Posted by kd0t

Mike, where can you choose to open/close the flap in JB4 software?

[boost82]

Originally Posted by kd0t

Mike, where can you choose to open/close the flap in JB4 software?

If you have the latest jb4 firmware you can open and close it. Check the 54tech forums there is a thread about it

[chaddy74]

Tell me more ?? Is this on a N55 EWG Car ?

Originally Posted by boost82

If you have the latest jb4 firmware you can open and close it. Check the 54tech forums there is a thread about it

[boost82]

Originally Posted by chaddy74

Tell me more ?? Is this on a N55 EWG Car ?

Yeah it works on the S55 M3/M4 as well. If you have a auto trans it is super easy to open and close it. Manual trans you need to plug in USB. You can have it operate like oem, always open or always closed

[boost82]

[horsepower_and_hounds]

Back on topic...I have a N55 with a Stage 1 installed. No plans on doing a full blown JB4
So it is being claimed in this thread that the M235 has an active flap controlled by the DME? Then doing the flap mod can be detrimental the the overall performance/function of the flap in relevance to the exhaust and engine mapping? Guess to make the question easier is it better to leave the DME control the flap with the piggy back or should i do the flap mod again.....

[boost82]

Originally Posted by ehagerty

Back on topic...I have a N55 with a Stage 1 installed

The main purpose of it is to quiet down the car. You def want it open at full throttle but if you like the way it sounds always open I would go for it. If not or you are not impressed by it I would let it operate like stock. If you want to go back and forth pretty easily I would look into this can flap module or a jb4 upgrade. IMO you are not losing any performance letting it operate like stock or gaining much by keeping it open. I think you should do what makes you happiest

[boost82]

The flap on your muffler has nothing to do with boost or engine mapping trust me

[horsepower_and_hounds]

Originally Posted by boost82

The main purpose of it is to quiet down the car. You def want it open at full throttle but if you like the way it sounds always open I would go for it. If not or you are not impressed by it I would let it operate like stock. If you want to go back and forth pretty easily I would look into this can flap module or a jb4 upgrade. IMO you are not losing any performance letting it operate like stock or gaining much by keeping it open. I think you should do what makes you happiest

Thank you
I just want what is best for operation of the tune/MPE/Car and not as educated on all this hop up stuff. Think I might do the flap open again but I know how some times corking off the exhaust can help things on the low end. I just don't like to change things and have an adverse effect on function and performance. guess in a nutshell I am trying to learn with limited resources

[Mike@N54Tuning.com]

Originally Posted by ehagerty

Back on topic...I have a N55 with a Stage 1 installed. No plans on doing a full blown JB4
So it is being claimed in this thread that the M235 has an active flap controlled by the DME? Then doing the flap mod can be detrimental the the overall performance/function of the flap in relevance to the exhaust and engine mapping? Guess to make the question easier is it better to leave the DME control the flap with the piggy back or should i do the flap mod again.....

If you plan to stay Stage1 then this might be just what you need! It has lots of other cool features too.

[horsepower_and_hounds]

Yea Mike....I was checking it out. I really just want a plug and forget set up and let all things be auto so to speak. Either leave it plugged in or unplug it. I am leaning towards unplugging it again but if it actually closes and opens to increase drive ability and power at different spots in the power curve then I should leave it plugged in. If it only effects sound then I will probably unplug it

[CG Precision]

Originally Posted by ehagerty

Yea Mike....I was checking it out. I really just want a plug and forget set up and let all things be auto so to speak. Either leave it plugged in or unplug it. I am leaning towards unplugging it again but if it actually closes and opens to increase drive ability and power at different spots in the power curve then I should leave it plugged in. If it only effects sound then I will probably unplug it

The automatic operation designed in by BMW accomplishes 2 things:

1. To warm up the catalytic converter fast, BMW has the wastegate open up to ~70% on startup to allow the hot gas to bypass the turbine section of the turbocharger, so the hot gas warms the cat and not the turbo immediately. This makes for a loud cold start. BMW closes the valve on startup to minimize the sound on cold start.

2. Since the car was engineered to have different suspension and drivetrain settings for different modes, it makes sense for BMW to use this feature along with the exhaust valve to appeal to a broader audience. Those who don't care about performance so much can leave it in comfort mode and get a quieter driving experience.

The muffler and exhaust valve design was only done to affect sound and setting it open, closed, or auto comes down to your preference.

We offer a plug and forget setup, the VSC-1 controller. It installs directly onto the exhaust valve motor and is emissions and dealer safe. You can configure it different ways but the standard setup is to default the exhaust valve to open, but allow remote closing of the valve if you wish to decrease the exhaust sound at any time. By using our controller you would get the performance you want and also protect the exhaust valve connections.

http://www.cgprecision.com/cms/index...und-controller

If you don't go with a controller and just unplug the exhaust valve, make sure you tape up both connections to minimize corrosion of the pins in the connector and the motor. We studied the factory exhaust valve operation extensively in all driving modes, throttle positions, and load scenarios before designing a controller for it so any more questions, just ask!

Walter

[horsepower_and_hounds]

Walter...Thank you much for the explanation. I will do the unplug mod again since I installed the Stage 1 and see the results. I had done it with the MPE and put it back to "plug in" since it really didn't do much.