[nozydog]

Originally Posted by goj

I hate having to clean both tail pipes, can I code the valve to be permanently closed so I only have to clean one?

I love polishing my tips regularly!!

[hollandog]

Originally Posted by nozydog

My car does exactly as you describe and I can't see any reason to do the unplug mod when all you have to do is push 'sport' after start up! I suppose it may sound more meaty on start up with the flap open but, apart from that there seems no reason to me to mess with it, particularly as the world class engineers at BMW designed it this way for a reason!!

what's the reason?

[nozydog]

Originally Posted by hollandog

what's the reason?

are you saying you don't think there is a reason? The first post on this thread suggests some possible reasons!

[DrGadget]

Good to read this sticky! Yes, the discussion will still keep popping up all over the forums. LOL

[turbocomppro]

I noticed that someone mentioned that if you have the MPE (which I will be installing next week), it will be opened on comfort mode? How does the car know you have a MPE? I don't recall any coding involved in installing a MPE...

[Blubaron79]

Originally Posted by turbocomppro

I noticed that someone mentioned that if you have the MPE (which I will be installing next week), it will be opened on comfort mode? How does the car know you have a MPE? I don't recall any coding involved in installing a MPE...

No, but after the car warms up both pipes work on my MPE in comfort. I don't know why

[turbocomppro]

Originally Posted by Blubaron79

No, but after the car warms up both pipes work on my MPE in comfort. I don't know why

That is indeed strange. I do wonder if it has any other positive function besides controlling emissions and sound.

[z3n0mal4]

Originally Posted by Chris_Azz94

First off I apologize I'm new here. Quick question about the flap though. Not sure if this was the right place to reply but, If I consider doing a muffler delete and remove the flap completely (just replace with a Y.) Will I get a CEL or any other malfunction?

I'd like to know too. Anyone?

Originally Posted by turbocomppro

That is indeed strange. I do wonder if it has any other positive function besides controlling emissions and sound.

Warming up the cat faster is also for emissions, so i guess we're just saving polar bears (quote needed) with this, nothing more.

[x97Melbourne]

Great pictures on this post -- thanks. I used a plastic "zip tie" to basically do the same thing. But I like your metal clip idea better.
Have done the zip tie on my last 2 cars. 335i and now 435i. Exhaust note does sound slightly better with that 2nd butterfly valve is open all the time.

You're right...takes 3 minutes max.

[vame95]

Great info in this post. Thanks for the help!

[epeabs]

Total Noob here. Just got my '15 435i xdrive convertible last Friday. Haven't had enough time to notice this exhaust "phenomenon" but now I know if I notice it. Thanks.

[nozydog]

Both my tips have exactly the same amount of carbon deposit on, I guess that proves that the flap is always open in sport mode, as I ALWAYS use sport mode. Can't accept the dull throttle and light steering in comfort mode!

[Joe Vona]

Originally Posted by Rick Hunter

2016 F36 435xi here. Exhaust valve logic for other F3x does not equate to F36. Tried everything, and CANNOT get the valve to open. If there's another '16 F36 owner that has figured it out... don't bother explaining it to me... I've gone to option 2, and it took less time compared to everything I've done above.

Decided to do the U-Clip disconnect. 10 minutes total DIY, and no need to disconnect any harnesses. Easy to reconnect if I ever need to.

Here's a view of the clip in place from the other side of the exhaust:


Here's the clip (on my work towel :-)


...and the wire that keeps the flap in the open position:

Nice work towel!

[Cafarca]

Thanks!

[7iM3less]

Hey, alternatively can't you just unplug the module after both valves are open and the baffles will permanently stay open?

[TopDog90]

Thanks , Helps Alot

[TumblingPanda]

Originally Posted by KC328_F30

Hey, alternatively can't you just unplug the module after both valves are open and the baffles will permanently stay open?

You can. Even better, turns out the valve is spring loaded to stay open. So when the engine is shut off, the valve is open. Looks like it closes immediately after the engine starts (left side exhaust pipe). At least, that was the case with my 2013 335i. When my buddy who owns an M4 told me this, I was surprised and checked it with a flash light. I simply pulled off the connector when the car was shut off, covered both ends of the connector with insulation tape to prevent water and dirt from entering, and it worked! Also, the top part of the rubber grommet used for suspending the exhaust muffler seems to be a good cool (relatively!) place to wrap the otherwise dangling connector.

There were no error codes and it has been about 2 yrs and everything seems to work just fine! And, yes I've check that the valve stays open and exhaust gases come out of both the tips all the time

[joanjgm]

Good to know, it was driving me nuts

[BMRSEB]

Originally Posted by z3n0mal4

I'd like to know too. Anyone?

To address the muffler delete question, since I recently did the muffler delete.. No, no check engine lights or any codes stored.. I just wrapped up the connector neatly and tucked it under the bumper.. There's a nice little "shelf" for it..

However, be prepared for drone at low speeds, high load and cruising! To the point where, I am considering putting the stock muffler back on and perhaps at some point getting the AA exhaust or similar.

At (cold) startup it sounds loud as hell, then drops down to a nice rumble, would be nice if this low rumble was the "stock" sound, post muffler delete.. I will miss the pops and crackles at gas let off, but growing tired of having to shift to combat drone..

[crank73]

I think my flap is frozen or stuck closed. My left pipe (single sided 428i exhaust) is frosty and ice covered (-25 to -30 deg C for the last 2 weeks here).
I am trying to get the valve open so that I can disconnect the electrical connector.
My question is, if I can't get the valve opened normally through the cars exhaust logic and vacuum, will the 'wire mod' open the valve as I tighten down and twist it in place?

[CT1]

Originally Posted by nozydog

are you saying you don't think there is a reason? The first post on this thread suggests some possible reasons!

There is always a reason....having the flap closed will increase exhaust back pressure and therefore torque at low revs, as the revs rise the engine gets past the low to mid high torgue range and then needs extra exhaust flow to produce maximum power hence the flap opens on hard acceleration creating extra flow.

This is all about tuning the exhaust for best all round performance. Disabling it will also affect the cars fuel consumption ie. it will get worse as the engine is not running efficently as intended. It may also take away some of the smoothness in start up and normal acceleration.

Just my two pennys worth.

CT

[paimon.soror]

sucks, i wish i came here before i ordered the exhaust dummy plug. You can add me to the list of 'i noticed the f36 def has a different logic for the flap'.

I wonder why....


PS. the bit about backpressure is hogwash. wayyyy too far downstream to impact backpressure lol. As mentioned it is for cat efficiency, but also because cold starts on this car are quite a bit "loud" (if you have a DP, you know...) for the non-car-fanatic BMW drivers.