N54 exhaust flap fault (not the usual)..

[ManiacGT]

My 35i has lost vacuum to the solenoid/valve in the trunk/boot. It's not the usual exhaust valve failure (which I had once before). This time there's very little vacuum at the valve. Having taken all the trim out to access the solenoid/valve the electrical feed is ok and having removed the vacuum pipe that is in the input side there's very little vacuum. So this means the feed from the engine is faulty. Question is does anyone know where the feed that goes to the back of the car starts in the engine bay so I can further diagnose the issue?

[jparnes1]

Originally Posted by ManiacGT

My 35i has lost vacuum to the solenoid/valve in the trunk/boot. It's not the usual exhaust valve failure (which I had once before). This time there's very little vacuum at the valve. Having taken all the trim out to access the solenoid/valve the electrical feed is ok and having removed the vacuum pipe that is in the input side there's very little vacuum. So this means the feed from the engine is faulty. Question is does anyone know where the feed that goes to the back of the car starts in the engine bay so I can further diagnose the issue?

How did you know you had this problem? Did the car throw a code?

[ManiacGT]

A rattle. Initially I thought it was the turbo wastegate issue but after a while the exhaust just went from a rattle to fully open all the time.

[Alext]

What sort of rattle is it - high pitched etc?

Im not sure about the e89 but usually these pipes take the pressure from the throttle body?

[ManiacGT]

I've had some assistance on this from the N54 tech forum. The feed for the exhaust valve is supplied from a T pipe on the brake assist vacuum line (fed by a vacuum pump on the engine). The -ve pressure at the T is significant, but at the feed to the solenoid valve in the boot/trunk there's very little. So there's either a leak or a blockage/kink. I intend to do more work on this next weekend when I have more time. I'll keep you updated in case anyone else gets this on their older e89's.

[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, valve 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've 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

[KennyP]

Just do the "Golf T" mod? Unhook the the vacuum line from solenoid and plug it with something. This leaves the flap always open. it makes a difference in noise low rpm, more crackles and cold starts are pretty loud.


I have been driving with the flap open for years now.

[Asbjorn]

Originally Posted by 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, valve 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've 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

1 The vacuum line to the exhuast flap Ts into the vacuum for the brake booster. You will find it in front of the brake booster.

2 After cold start sequence is done, the exhaust flap is always open in 1st and 2nd gear. It then closes in 3rd gear unless you are pushing the throttle more than normal. It opens whenever you start to demand power or when the rpms climb above a certain rpm. The map shouldn't influence the exhaust flap behaviour unless your tuner tried to do some magic. If your tuner tried to alter the exhaust flap behaviour, you better ask him to use the stock one. You cannot use for instance the 1M exhaust flap map on the Z4.

If the problem happened right after a map flash, try and let the car sit over night and test again the next day. Mine sometimes wont close right after a flash.

[TWOZTER]

Originally Posted by KennyP

Just do the "Golf T" mod? Unhook the the vacuum line from solenoid and plug it with something. This leaves the flap always open. it makes a difference in noise low rpm, more crackles and cold starts are pretty loud.


I have been driving with the flap open for years now.

Somewhat related question: Have had my 2011 35is for about 6 months now...flap has been open for a long time, before my ownership. I have tried every fix I know of and have read about (spring tension on the actuator rod, etc.) and I get the rattle bad at idle after the car has warmed up and everything has expanded...anyone have any other ideas? Can a "valve-ectomy" be done? My searches on this and every other z4 forum has come up with nada...damn embarrassing at stop lights.

[KennyP]

Originally Posted by TWOZTER

Somewhat related question: Have had my 2011 35is for about 6 months now...flap has been open for a long time, before my ownership. I have tried every fix I know of and have read about (spring tension on the actuator rod, etc.) and I get the rattle bad at idle after the car has warmed up and everything has expanded...anyone have any other ideas? Can a "valve-ectomy" be done? My searches on this and every other z4 forum has come up with nada...damn embarrassing at stop lights.

I fixed my valve actuator rod with a zip tie so it couldnt easily move unintentionally. No flap rattle. At first when i disconnected my exhaust valve it closed itself in a few days, Probably because of bumpy roads, vibrations or something. Thats why i added a ziptie to the rod. And it solved that issue. Never closed on me again.

[TWOZTER]

I'll give that a try....any pics of your solution?

Thanks!

[KennyP]

Originally Posted by TWOZTER

I'll give that a try....any pics of your solution?

Thanks!

Cant take pics right now. Car is in the shop right now. Maybe in a few days i will have it back.

[TWOZTER]

Great! If you think of it, snap a pic when you get a chance...would love to see the solution.

John