E90 335i Exhaust Flap

[vjx]

Hey X35i guys,

Have you checked your exhaust flaps on the left side of exhaust pipe?
Mine seems like staying in 'OPEN' position permanently, hence I feel drone at the speed of 120Km/h when giving a little bit throttle uphill.
Some source from Internet showing, cold start or RPM under 2500rpm, the flap should stay closed, in order to warm up cat quickly and reduce noise.
No error from ECU as the switch showing no electrical fault.
Diaphragm is integrated with exhaust, if broken, whole muffler needs to get replaced.
What's the best place to check it up and give a affordable solution on this matter?

Thanks.

 

[Kish2604]

Trace the vacuum pipe from engine bay to exhaust solenoid to see that it holds vacuum?

 

[vjx]

Kish, I will check it tonight.
Thanks.

 

[t0by_o7]

Check if it is plugged in mine was plugged out when I bought thr car. It plugs in at the back of your left tailight. Remove cover in die boot behind the light and you will see the plug.

 

[vjx]

I've checked the boot at the left corner lights.
Put all plugs back to original place. The intake vacuum hose was lose. But it didn't cure the problem.
I think the car was fixed by dealers in past years. When assemble back, something was not put back into place.
I will check front today.

 

[vjx]

Switched two vacuum pipes to wastegate solenoid and rear of cars.
No luck. No disconnection anywhere. Tried to blow the pipe, it seems pretty blocked by the other end.
It can either be the switch at rear not working or the diaphragm.

 

[KarshS]

is the car stock? No JB or software?

 

[vjx]

Car is stock no ECU mod or piggy back.
I bought a vacuum tester today. I will check vacuum pressure and diaphragm.

 

[vjx]

To continue,
Start the car, vacuum feeder pipe on the switch gives good vacuum. You can hear and feel it when the pipe out of nozzle.
The electric wire gives 10.7V to the switch when engine on idle, 8.7V when engine off.
The outlet vacuum nozzle on the switch doesn't have any vacuum when the switch and engine on idle.
Direct connect the vacuum feeder to the diaphragm, basically by pass the switch, the flap is reluctant to close. Give a hard push by a screw driver, the flap can stay at close position. It seems like the vacuum is not enough to drive diaphragm to close the flap.

Question:
1. No idea if the switch should or can operate at 10.7V.
If can, the switch is not functioning, but no error on ECU.
2. The diaphragm might be broken too, if the switch doesn't provide any extra force to operate diaphragm. Too expensive to replace half of exhaust.
3. Later N55 has electric exhaust flap control, can it be retrofit on the vacuum controller flap?

I think I have a retrofit by default that the exhaust flap permanent open without error. No need for Golf Tee mod. mgwaiting:

 

[Royce77]

I can assist with a replacement solenoid if you need. I always leave mine disconnected :biglol: