Exhaust Flap - Is there an app?

[Anonymous]

That’s surprised me, the brake servo requires vacuum assistance permanently in order to work as does the exhaust flap.
lci cars have solonoid controlled wastegates which are electronic, but the other items would need the vacuum pump running constantly so why is the raspy/blowing sound only evident on cold start-up? It does sound as though it emanates from around the turbo area :?
Rob

Dear Concerned..Correct, True, Pass, Maybe

I get all that (except my model doesn’t have a vacuum powered wastegate)
So why is it so loud on initial cold start? Does the pump work extra hard to prime the reservoir i wonder?
Rob

I assume it runs flatout to build vacuum ASAP as you want your brakes to work 100% as soon as you start to roll, it then quietens down I suspect because:

Its 'filled' actually emptied the resevoir

Its warmed up

You can't hear it as you are driving lsitening to Max Bygraves..

Consumption of vacuum is probably majority going to the braking system, wasn't worth them changing it when they brought the turbo electric servo in..

There were some re-calls where the pump failed and the brakes didn't work too well..

 

[MACK]

Just a thought, you could take a spare fuse slot in the fuse box, run a few wires to the solenoid and a switch in the cabin (down where the blanked off boot release is maybe) then have it manually switchable to loud and quiet?

I was thinking along similar lines although i'm probably just going to use the existing live feed (which is working fine) to the solenoid and just rig a switch up for the earth side. I was thinking or putting it between my cup holders in the arm rest, but I'm just going to try it all temporarily before a permanent install

I’m wondering if that might flag up a fault code? :?
Rob

Unplugging the solenoid does, so I'm fully expecting it to. However it "soft codes" into the ecu without bringing on a warning light/message etc. So you only see it if you go looking for it so to speak. I can't see why cutting the switching earth back to the ecu would be any different, only one way to find out!

 

[MACK]

I was thinking along similar lines although i'm probably just going to use the existing live feed (which is working fine) to the solenoid and just rig a switch up for the earth side. I was thinking or putting it between my cup holders in the arm rest, but I'm just going to try it all temporarily before a permanent install

I’m wondering if that might flag up a fault code? :?
Rob

Unplugging the solenoid does, so I'm fully expecting it to. However it "soft codes" into the ecu without bringing on a warning light/message etc. So you only see it if you go looking for it so to speak. I can't see why cutting the switching earth back to the ecu would be any different, only one way to find out!

Well I went ahead and did this little mod today and it works a treat. The hardest bit as ever with this sort of thing is routing the wiring and it was a bit of a pain, But that said, now I know how/where to route it I could probably do the whole job again in under an hour.
So the long and short of it is I've now got an operating exhaust valve again, that I can switch on/off via a little rocker switch I've currently got temporarily under the armrest. Its likely that's where it will stay permanently, mounted between the two cup holders but I haven't quite decided yet. So far so good in terms of warning lights, not that the cars been anywhere. I haven't scanned it yet, but I do expect the same code to be in the ecu that was there when I unplugged the solenoid.

 

[Smartbear]

I’m wondering if that might flag up a fault code? :?
Rob

Unplugging the solenoid does, so I'm fully expecting it to. However it "soft codes" into the ecu without bringing on a warning light/message etc. So you only see it if you go looking for it so to speak. I can't see why cutting the switching earth back to the ecu would be any different, only one way to find out!

Well I went ahead and did this little mod today and it works a treat. The hardest bit as ever with this sort of thing is routing the wiring and it was a bit of a pain, But that said, now I know how/where to route it I could probably do the whole job again in under an hour.
So the long and short of it is I've now got an operating exhaust valve again, that I can switch on/off via a little rocker switch I've currently got temporarily under the armrest. Its likely that's where it will stay permanently, mounted between the two cupholders but have quite decided yet.

What’s your verdict between the two modes (assuming you’ve been able to get out) :?
Rob

 

[MACK]

Unplugging the solenoid does, so I'm fully expecting it to. However it "soft codes" into the ecu without bringing on a warning light/message etc. So you only see it if you go looking for it so to speak. I can't see why cutting the switching earth back to the ecu would be any different, only one way to find out!

Well I went ahead and did this little mod today and it works a treat. The hardest bit as ever with this sort of thing is routing the wiring and it was a bit of a pain, But that said, now I know how/where to route it I could probably do the whole job again in under an hour.
So the long and short of it is I've now got an operating exhaust valve again, that I can switch on/off via a little rocker switch I've currently got temporarily under the armrest. Its likely that's where it will stay permanently, mounted between the two cupholders but have quite decided yet.

What’s your verdict between the two modes (assuming you’ve been able to get out) :?
Rob

I've not be able to drive it anywhere yet, but I definitely think the neighbours will prefer it, especially at 6 in the morning! To be honest I do prefer it closed, the sound it makes at start up with it open is a very loud farty noise, not a nice exhaust note at all quite embarrassing really. Start up is definitely much nicer with the valve closed.

 

[enzed4]

Unplugging the solenoid does, so I'm fully expecting it to. However it "soft codes" into the ecu without bringing on a warning light/message etc. So you only see it if you go looking for it so to speak. I can't see why cutting the switching earth back to the ecu would be any different, only one way to find out!

Well I went ahead and did this little mod today and it works a treat. The hardest bit as ever with this sort of thing is routing the wiring and it was a bit of a pain, But that said, now I know how/where to route it I could probably do the whole job again in under an hour.
So the long and short of it is I've now got an operating exhaust valve again, that I can switch on/off via a little rocker switch I've currently got temporarily under the armrest. Its likely that's where it will stay permanently, mounted between the two cupholders but have quite decided yet.

What’s your verdict between the two modes (assuming you’ve been able to get out) :?
Rob

I've not be able to drive it anywhere yet, but I definitely think the neighbours will prefer it, especially at 6 in the morning! To be honest I do prefer it closed, the sound it makes at start up with it open is a very loud farty noise, not a nice exhaust note at all quite embarrassing really. Start up is definitely much nicer with the valve closed.

A bit of a late answer now that you've wired in a solution, but MHD Flasher seems to have settings that do what you were asking about originally, but not for the N20 unfortunately. I have added an option in my tune that changes the startup to a quiet idle as the cold start noise was quite annoying/harsh. The difference is remarkable. I would have thought that if this was do-able on the N54 then something would have been available for the N20, but perhaps not, as they are different engines after all.
Good to see you've achieved what you wanted with a mechanical solution. You may find other N20 owners asking for instructions on how to do this as well

 

[MACK]

Well I went ahead and did this little mod today and it works a treat. The hardest bit as ever with this sort of thing is routing the wiring and it was a bit of a pain, But that said, now I know how/where to route it I could probably do the whole job again in under an hour.
So the long and short of it is I've now got an operating exhaust valve again, that I can switch on/off via a little rocker switch I've currently got temporarily under the armrest. Its likely that's where it will stay permanently, mounted between the two cupholders but have quite decided yet.

What’s your verdict between the two modes (assuming you’ve been able to get out) :?
Rob

I've not be able to drive it anywhere yet, but I definitely think the neighbours will prefer it, especially at 6 in the morning! To be honest I do prefer it closed, the sound it makes at start up with it open is a very loud farty noise, not a nice exhaust note at all quite embarrassing really. Start up is definitely much nicer with the valve closed.

A bit of a late answer now that you've wired in a solution, but MHD Flasher seems to have settings that do what you were asking about originally, but not for the N20 unfortunately. I have added an option in my tune that changes the startup to a quiet idle as the cold start noise was quite annoying/harsh. The difference is remarkable. I would have thought that if this was do-able on the N54 then something would have been available for the N20, but perhaps not, as they are different engines after all.
Good to see you've achieved what you wanted with a mechanical solution. You may find other N20 owners asking for instructions on how to do this as well

Thanks, to be honest with the number of N20 cars that seem to be reporting this issue I'm becoming increasingly convinced that the none working exhaust valve due to no earth is actually a fault, rather than some aftermarket software turning it off. That or an official BMW software update is turning it off, possibly inadvertently when cars have been into main dealers. At least the switch mod I've done, although a bigger pain to install is a lot cheaper than those remote control versions on the net.

 

[Player 1]

Just a thought, you could take a spare fuse slot in the fuse box, run a few wires to the solenoid and a switch in the cabin (down where the blanked off boot release is maybe) then have it manually switchable to loud and quiet?

I was thinking along similar lines although i'm probably just going to use the existing live feed (which is working fine) to the solenoid and just rig a switch up for the earth side. I was thinking or putting it between my cup holders in the arm rest, but I'm just going to try it all temporarily before a permanent install

Good to hear you got it done! If you don't mind, is there any chance of some pictures or a bit of info on where you routed the wiring?
My original thought was to take a donor exhaust from another 35i/35is and fit the second valve'd muffler in place of the normal one on the left so there's two valves. I got as far as rigging up a test solenoid with some vacuum lines to see if the vacuum would pull the two valves simultaneously and it worked a treat. My main concern though was what excess back pressure might do with all the exhaust flow trying to go through the two little pipes, cutting them off to fit larger may be the option however that's as far as I got with it!

 

[MACK]

Just a thought, you could take a spare fuse slot in the fuse box, run a few wires to the solenoid and a switch in the cabin (down where the blanked off boot release is maybe) then have it manually switchable to loud and quiet?

I was thinking along similar lines although i'm probably just going to use the existing live feed (which is working fine) to the solenoid and just rig a switch up for the earth side. I was thinking or putting it between my cup holders in the arm rest, but I'm just going to try it all temporarily before a permanent install

Good to hear you got it done! If you don't mind, is there any chance of some pictures or a bit of info on where you routed the wiring?
My original thought was to take a donor exhaust from another 35i/35is and fit the second valve'd muffler in place of the normal one on the left so there's two valves. I got as far as rigging up a test solenoid with some vacuum lines to see if the vacuum would pull the two valves simultaneously and it worked a treat. My main concern though was what excess back pressure might do with all the exhaust flow trying to go through the two little pipes, cutting them off to fit larger may be the option however that's as far as I got with it!

Hi,

After stripping the plastic covers in the boot on the nearside(the solenoid is hiding under them) I ran a couple of wires from the solenoid hidden under the trim up to the bulkhead. My original plan was to try and feed them through near the ski hatch but after stripping the hatch and trim it became apparent that was a bit of a none starter. So I end up following the path of the wiring loom past the roof mechanism on the passenger side. Inside the cabin I removed the cover from the top seat belt anchor point and the speaker grille just below it. I then removed the small speaker behind it. In hindsight you dont need to remove the top seat belt mount cover, the grill is enough. Mines got the 14 speaker stereo system, so I'm not too sure what other specs might have in this area, but the speaker aperture allows you to feed the cables from the far passenger side of the boot into the cabin. Just be careful where you route the cables as you dont want any "complications" with the roof mechanism when its on the move!

Once you've got the cables in the cabin is fairly easy to route them to the center console where I removed the cup holders/storage tray (I previous already removed the redundant phone holder and its fittings etc).

the plan is to get one of these rocker switches and install it in the small recess between the two cup holder

 

[MACK]

Just to update this for anyone with a N20 with a similar issue thinking of following suit.
I took the car out yesterday as I had to pick up a prescription and deliver it to my Father. This mean't I had to do a short motorway journey as well as normal roads. On start up the flap in its closed position makes a massive difference, I can see why BMW bothered to fit it. No longer am I waking the dead with a loud crappy farty noise. With the flap closed its not too bad at all despite the extra noise of the air pump running, obviously after a couple of minutes that calms down too and it goes even quieter.
I have to say though, once that initial few minutes of running are over and everything has settled down. I think I prefer the extra noise of having the flap open on the move at low revs for a little extra drama. Don't get me wrong here, its never going to sound like an I6, but its a bit better than having it closed.
Moving on to motorway cruising at 60-70mph+. I can't tell any discernible difference between open and closed, neither could my wife. So for me the value of this mod (if you also have a none function exhaust flap on a N20 engined car) is for the first few minutes from start up. It'll keep your neighbours happy!

 

[Argyll Andy]

Once you've got the cables in the cabin is fairly easy to route them to the center console where I removed the cup holders/storage tray (I previous already removed the redundant phone holder and its fittings etc).

Maybe that’s what the 7th button Big Bad Boris was was asking about on the console is for and BM just forgot to wire it up

Post by Big Bad Boris » Wed Apr 15, 2020 12:38 pm

Another thing that’s puzzled me, the z4 has 7 buttons on the tunnel, 2 for heated seats, 2 for roof operation, one for parking sensors...what are the other 2 for.... I’ve looked at loads of these online but never seen one with all 7 buttons utilised.

 

[MACK]

I did spot that thread. I wonder if they had something in mind for for the facelift but decided against it or were just future proofing it.

 

[enuff_zed]

Just to update this for anyone with a N20 with a similar issue thinking of following suit.
I took the car out yesterday as I had to pick up a prescription and deliver it to my Father. This mean't I had to do a short motorway journey as well as normal roads. On start up the flap in its closed position makes a massive difference, I can see why BMW bothered to fit it. No longer am I waking the dead with a loud crappy farty noise. With the flap closed its not too bad at all despite the extra noise of the air pump running, obviously after a couple of minutes that calms down too and it goes even quieter.
I have to say though, once that initial few minutes of running are over and everything has settled down. I think I prefer the extra noise of having the flap open on the move at low revs for a little extra drama. Don't get me wrong here, its never going to sound like an I6, but its a bit better than having it closed.
Moving on to motorway cruising at 60-70mph+. I can't tell any discernible difference between open and closed, neither could my wife. So for me the valve of this mod (if you also have a none function exhaust flap on a N20 engined car) is for the first few minutes from start up. It'll keep your neighbours happy!

I'm crap at electric stuff.................... but I don't like my neighbours, so that's easy

 

[gg.feisbuk]

Dear

I've a problem with exhaust on my Z4 35i N54, related to the exhaust flap on the original right silencer
Two questions:
1) the tube that opens the exhaust valve, work's with vacuum? If so, where does this vacuum form the engine ?
2) with original map, the valve at the exhaust opening when the engine was cold and it was started, it stay open for a few seconds and then closed, then with the setting SPORT or SPORT + it opened when kick down the gas. Now after I mapped (387hp) the behavior of the valve at the exhaust has changed, at the start it behaves as before, but going into SPORT or SPORT + the valve opens in release, no in kick down. What may have happened ? is there a parameter in mapping to be fixed?

Thank's

 

[R.E92]

Dear

I've a problem with exhaust on my Z4 35i N54, related to the exhaust flap on the original right silencer
Two questions:
1) the tube that opens the exhaust valve, work's with vacuum? If so, where does this vacuum form the engine ?
2) with original map, the valve at the exhaust opening when the engine was cold and it was started, it stay open for a few seconds and then closed, then with the setting SPORT or SPORT + it opened when kick down the gas. Now after I mapped (387hp) the behavior of the valve at the exhaust has changed, at the start it behaves as before, but going into SPORT or SPORT + the valve opens in release, no in kick down. What may have happened ? is there a parameter in mapping to be fixed?

Thank's

The flap is vacuum operated and the supply to it comes from the line that feeds into the brake booster, it's teed off about 6 inches away from the booster IIRC.

With the exhaust valve logic there is no differentiation between normal and sport, only for roof up or down.
The standard logic for the exhaust flap is that the flap is always closed when the car is below 10mph unless the cold start sequence is active. The flap then opens at varying pedal positions depending on the RPM and gear the car is in. Typically the valve is closed until the revs get above 2500 or the accelerator pedal is at about 30% or more. It remains closed until going over 3200rpm in 7th gear.

The behaviour of the valve can be altered in the ECU so it's possible the tuner has changed the behaviour but unlikely given that most tuners don't have the access required to all the exhaust tables.

 

[mcbutler]

Carly operates the exhaust flap I believe. I am just puzzled why the ECU would want to control the earth? All it has to do is send a simple on/off surely??

 

[Smartbear]

Carly operates the exhaust flap I believe. I am just puzzled why the ECU would want to control the earth? All it has to do is send a simple on/off surely??

By switching the earth the ecu is still controlling the on/off function
Rob

 

[Anonymous]

Carly operates the exhaust flap I believe. I am just puzzled why the ECU would want to control the earth? All it has to do is send a simple on/off surely??

R.E92 pointed out that the logic control for the flap is much more complicated / nuanced depending on many factors which the DME has all the knowledge off and probably no other control unit does have all that data..

 

[gg.feisbuk]

Dear

I've a problem with exhaust on my Z4 35i N54, related to the exhaust flap on the original right silencer
Two questions:
1) the tube that opens the exhaust valve, work's with vacuum? If so, where does this vacuum form the engine ?
2) with original map, the valve at the exhaust opening when the engine was cold and it was started, it stay open for a few seconds and then closed, then with the setting SPORT or SPORT + it opened when kick down the gas. Now after I mapped (387hp) the behavior of the valve at the exhaust has changed, at the start it behaves as before, but going into SPORT or SPORT + the valve opens in release, no in kick down. What may have happened ? is there a parameter in mapping to be fixed?

Thank's

The flap is vacuum operated and the supply to it comes from the line that feeds into the brake booster, it's teed off about 6 inches away from the booster IIRC.

With the exhaust valve logic there is no differentiation between normal and sport, only for roof up or down.
The standard logic for the exhaust flap is that the flap is always closed when the car is below 10mph unless the cold start sequence is active. The flap then opens at varying pedal positions depending on the RPM and gear the car is in. Typically the valve is closed until the revs get above 2500 or the accelerator pedal is at about 30% or more. It remains closed until going over 3200rpm in 7th gear.

The behaviour of the valve can be altered in the ECU so it's possible the tuner has changed the behaviour but unlikely given that most tuners don't have the access required to all the exhaust tables.

Wonderful, many thank's for all of your informations, two questions more:
1) no differentiation between normal and sport, only for roof up or down. What's mean ? What's difference has the valve behaviour with the roof up or down
2) most tuners don't have the access required to all the exhaust tables. Is it possibile to know more about this table ? If I could have ore details i talk with my tuner to change setting in the exhaust table.

Many many thank's

 

[Smartbear]

Dear

I've a problem with exhaust on my Z4 35i N54, related to the exhaust flap on the original right silencer
Two questions:
1) the tube that opens the exhaust valve, work's with vacuum? If so, where does this vacuum form the engine ?
2) with original map, the valve at the exhaust opening when the engine was cold and it was started, it stay open for a few seconds and then closed, then with the setting SPORT or SPORT + it opened when kick down the gas. Now after I mapped (387hp) the behavior of the valve at the exhaust has changed, at the start it behaves as before, but going into SPORT or SPORT + the valve opens in release, no in kick down. What may have happened ? is there a parameter in mapping to be fixed?

Thank's

The flap is vacuum operated and the supply to it comes from the line that feeds into the brake booster, it's teed off about 6 inches away from the booster IIRC.

With the exhaust valve logic there is no differentiation between normal and sport, only for roof up or down.
The standard logic for the exhaust flap is that the flap is always closed when the car is below 10mph unless the cold start sequence is active. The flap then opens at varying pedal positions depending on the RPM and gear the car is in. Typically the valve is closed until the revs get above 2500 or the accelerator pedal is at about 30% or more. It remains closed until going over 3200rpm in 7th gear.

The behaviour of the valve can be altered in the ECU so it's possible the tuner has changed the behaviour but unlikely given that most tuners don't have the access required to all the exhaust tables.

Wonderful, many thank's for all of your informations, two questions more:
1) no differentiation between normal and sport, only for roof up or down. What's mean ? What's difference has the valve behaviour with the roof up or down
2) most tuners don't have the access required to all the exhaust tables. Is it possibile to know more about this table ? If I could have ore details i talk with my tuner to change setting in the exhaust table.

Many many thank's

With the roof down you can hear the exhaust more, so it’s adjusted to give a sportier sound. With the roof up the exhaust becomes more muffled as you can’t hear it anyway. That’s how I understand it
Rob