Biscuits Posted May 6, 2008 Report Share Posted May 6, 2008 Chaps, When I had a B6 S4, I disconnected the butterfly flap in the rear silencers and it made the exhaust note a bit better. I also did a similar mod with my Porsche 996 sports exhaust. I notice that BMW use a buterfly flap in their silencers and I'm guessing it's for noise regulations too? I disconnected the vacume pipe on my 535d last night, but to be honest, haven't notice a big difference... can't hear it over the oil burning lump in the front! Picking up a 130i tonight for the wife and wondered if it is worth doing it on that too??? Are there any aftermarket cat-back systems for the 130i ? Nothing on Milltek site. Link to comment Share on other sites More sharing options...
CarMad Posted May 6, 2008 Report Share Posted May 6, 2008 On the valve not sure but I have read that it can cause emissions issues on some cars and it can mean less torque at times apparently. On the new exhaust BMW are actually about to offer a performance stainless steel exhaust for the 1 and 3series six cylinder cars. Link to comment Share on other sites More sharing options...
ghibbett Posted May 7, 2008 Report Share Posted May 7, 2008 Picking up a 130i tonight for the wife and wondered if it is worth doing it on that too??? Hello! (Very) long time lurker here, but had to register after seeing this. I have a 130i M-Sport and have done this mod. Am an active member on babybmw.net and have posted details of how to do it (w/visuals) if needed. However it's well worth doing. Had mine modded (i.e. pulled & plugged the vacuum hose) for the last year and not had any problems re. warning lights/emissions etc. Valve stays open all the time therefore car is heard at all throttle openings and also throttle closed. Well worth doing. HTH Link to comment Share on other sites More sharing options...
Biscuits Posted May 7, 2008 Author Report Share Posted May 7, 2008 Hello!(Very) long time lurker here, but had to register after seeing this. I have a 130i M-Sport and have done this mod. Am an active member on babybmw.net and have posted details of how to do it (w/visuals) if needed. However it's well worth doing. Had mine modded (i.e. pulled & plugged the vacuum hose) for the last year and not had any problems re. warning lights/emissions etc. Valve stays open all the time therefore car is heard at all throttle openings and also throttle closed. Well worth doing. HTH Thanks for the advice... I'll do the mod tonight while the missus is looking the other way Link to comment Share on other sites More sharing options...
CarMad Posted May 7, 2008 Report Share Posted May 7, 2008 Hello!(Very) long time lurker here, but had to register after seeing this. I have a 130i M-Sport and have done this mod. Am an active member on babybmw.net and have posted details of how to do it (w/visuals) if needed. However it's well worth doing. Had mine modded (i.e. pulled & plugged the vacuum hose) for the last year and not had any problems re. warning lights/emissions etc. Valve stays open all the time therefore car is heard at all throttle openings and also throttle closed. Well worth doing. HTH Hi ghibbett and welcome to TSN. Post a like up of how its done to help everyone its no problem. I take it I can do similar on my 330i ?? Link to comment Share on other sites More sharing options...
Pincher Posted May 7, 2008 Report Share Posted May 7, 2008 When I had a B6 S4, I disconnected the butterfly flap in the rear silencers and it made the exhaust note a bit better. You never told me that! I would never have bought it if I'd known! Link to comment Share on other sites More sharing options...
Biscuits Posted May 8, 2008 Author Report Share Posted May 8, 2008 You never told me that! I would never have bought it if I'd known! You don't know the half of it.... Link to comment Share on other sites More sharing options...
ghibbett Posted May 8, 2008 Report Share Posted May 8, 2008 Oaky doke, here's how to do it 1. Exhaust valve is located here: 2. Here you see the valve with the vacuum hose attached. 3. Pull off the vacuum hose. I then plugged it by screwing a screw into it. Nice and secure. Hey presto! I take it I can do similar on my 330i ?? I have never had a poke about the rear of a E90 330i (), however I would imagine that BMW use the same Pierburg Valves across all model lines, as it would be cost ineffective not to do so. Therefore, although the rear silencer would be different, the valve should be the same. Oh, and remember to plug the vacuum hose! Cheers Link to comment Share on other sites More sharing options...
CarMad Posted May 8, 2008 Report Share Posted May 8, 2008 Thats great thanks, might have a look at doing it on mine. Link to comment Share on other sites More sharing options...
Biscuits Posted May 8, 2008 Author Report Share Posted May 8, 2008 Thats great thanks, might have a look at doing it on mine. CARMAD: I think the 330i will be more like the 535d and S4 silencer(s), where the valve is easier to locate... it took a bit of effort to find the one on the 130i, but on my 535d it's staring right at you on top of the right hand pipe. Thanks for the pictures, much appreciated Link to comment Share on other sites More sharing options...
Omi Posted May 26, 2008 Report Share Posted May 26, 2008 Where do these valves take vacuum from? - My ECU will throw up errors in the E30 because this valve is missing. - Thought I might look at retrofitting it. Link to comment Share on other sites More sharing options...
Biscuits Posted June 1, 2008 Author Report Share Posted June 1, 2008 Where do these valves take vacuum from? - My ECU will throw up errors in the E30 because this valve is missing. - Thought I might look at retrofitting it. Not sure where it's taken from. On the Porker it was a vacum resevoir sat right on top of the engine, so easy to trace the tubes... I did spot the green thin tube in the S4 engine bay, not looked in the 1 or 5er. I guess if your car hasn't had the tube plugged, then it could be throwing an error due to it thinking the tube is totally open ??? P Link to comment Share on other sites More sharing options...
MadMark Posted September 12, 2008 Report Share Posted September 12, 2008 OK - when is this flap meant to open and close? :confused: I've just been out and the flap is open with the engine switched off -so I fired up my car from cold and the exhaust flap stayed wide open. Revving the engine seems to make no difference! Link to comment Share on other sites More sharing options...
CarMad Posted September 12, 2008 Report Share Posted September 12, 2008 Low revs it stays closed I think to keep the sound down, over 4000 rpm it opens up to allow for a nicer turn to come out. Changing it leaves it open so you get more of a burble a low revs. I haven't done it on mine yet but I will give it a try when I get chance. Link to comment Share on other sites More sharing options...
MadMark Posted September 12, 2008 Report Share Posted September 12, 2008 Low revs it stays closed I think to keep the sound down, over 4000 rpm it opens up to allow for a nicer turn to come out. Changing it leaves it open so you get more of a burble a low revs. I haven't done it on mine yet but I will give it a try when I get chance. Is this dictated by ECU programming?? As I get loads of "burble / brrrm" everywhere (well up to 4,000 rpm when it starts to growl) and as my flap doesn't close - it sounds like mine is stuck open then! Link to comment Share on other sites More sharing options...
CarMad Posted September 12, 2008 Report Share Posted September 12, 2008 Yeah mine is like that as well but apparently there is more to be had apparently. Some complain about a resonance at motorway speeds as a knock on effect though and I certainly don't get that. Let me know if you have a go at blocking it off. Link to comment Share on other sites More sharing options...
MadMark Posted September 12, 2008 Report Share Posted September 12, 2008 Yeah mine is like that as well but apparently there is more to be had apparently. Some complain about a resonance at motorway speeds as a knock on effect though and I certainly don't get that. Let me know if you have a go at blocking it off. I am still getting used to the howl between 6K and 7K ...:D Already tried - couldn't detect any difference but will have another play tomorrow! Link to comment Share on other sites More sharing options...
CarMad Posted October 16, 2008 Report Share Posted October 16, 2008 Well I've done mine and I can certainly tell the difference. Its not boomy at speed at all but you do notice more of a sound from the rear under partial load at cruising speed. About town and getting up to speed it's a little more vocal but nothing dramatic, all in all a nice free little upgrade thats worth doing if you want a little more tune from the exhaust in your 6 cylinder motor. The howl from the engine is still there and as good as ever still. Link to comment Share on other sites More sharing options...
cruiser647 Posted October 31, 2008 Report Share Posted October 31, 2008 I have noticed even the new A4 TDi has this exhaust flap. Link to comment Share on other sites More sharing options...
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