[Jojomosgo]

I had the notorious timing chain guide failure, fortunately repaired under warranty, however it was returned to me with a chattering butterfly exhaust flap. The dealer told me it failed insisting it must have been a problem waiting to happen, 62K miles. I disconnected the valve in the back of the car to kill the chatter, and went on a trip. Apparently the increased back pressure was enough to cause a drive train malfunction error, same error that it posted when the timing chain guide failed. I immediately pulled over, it reset, I made an appointment with the dealer for Monday and drove the rest of the weekend without incident. Meanwhile no chattering. I drop it at the dealer thinking it may be timing chain repair related, they call to tell me it’s because I disconnected the valve in the back and $160 later they give me back a chattering X3 and tell me I have to replace the muffler. I go and buy the muffler from getbmwparts for $650, the dealer had quoted me $1200 to do it, and I replace it myself. Damn thing is still chattering. There is vacuum, but my suspicion is that it is not enough vacuum. The dealer refused to even check. Help, anyone? Thoughts, suggestions? Here I am with a perfectly good muffler that I cut off the exhaust and a brand new one that is clamped on using the BMW clamp, and it’s exactly the same as before I started this exercise.

[doodlebro]

I highly doubt the disabled flap caused enough backpressure to give a drivetrain malfunction. Correlation does not equal causation.

The flap is controlled by vacuum lines and I've never thought that it was designed to work anywhere except at sea level... Altitude reduces effective vacuum.

[Wgosma]

Sounds like 2nd opinion from reputable independent shop may be in order.

Good luck/Bill

[Jojomosgo]

[Jojomosgo]

So, got another drivetrain malfunction error today, with the exhaust flap active, though it does chatter. I am fairly certain the dealer does not know what they are talking about. Tomorrow I will talk with the service manager.

[TheCoolX3]

Its likely the actuator itself.

[oVeRdOsE.]

I've used a ziptie , but this is the idea

[doru]

I had that rattle on my BMW e92. I unplugged the valve, and all is good. Then, I purchased a repair kit from AGA. Not sure if it's the same system on the X3 F25, but it looks eerie similar. Here is the link for the repair kit. Not sure if it fits the F25, but you can always call Mr. Christiansen - he's the owner of the shop, and he is the guy who develops special tools and better small parts for German cars. he can tell you if it will fit or not, or what your options could be. Keep us posted, and GL (Check the vid that is in the link, you will see the guy, and also how it's fixed)

P.S.: kit is not cheap, but much cheaper than exhaust system, which will also eventually fail even if it's changed. Kit will outlast the exhaust. Win-win.

[rotax]

I just recently went through the exact same thing except no timing chain issue. Started to get exhaust flap chatter followed by periodic and increasing drivetrain malfunction errors. 2011 X3 35iX @ 93k miles

I too assumed the good ole golf tee fix was in order initially except unlike my 04 X3 this was easier to access in the trunk area. I was happy the chatter was gone but was clueless about what the drivetrain issues were about. I was also experiencing some power surging during heavy acceleration I started by changing the plugs and coil packs and a dose of Techron to clean the injectors which seemed to resolve the surging but did not fix the drivetrain malfunction errors. I was headed for fuel injector replacement after having read these were all common causes of drivetrain malfunction errors. But before deciding to pay over $600 for new injectors I noticed that the drivetrain malfunction error was cleared each time I restarted the car. So the next time it happened I kept the car running and read out the code. What it showed was a 120308 Boost Pressure Control, Plausibility: Pressure Too Low

Doing some searching around I found this file online

For me I had no other codes. so this seemed like the appropriate route for determining the problem. I had just recently replaced the spark plugs and coil packs so I had the intake off. I was quite sure I had no intake leaks from what I could see and there were no lean codes, so that left me on the pressurized side.

I assumed I had no major leaks on the pressurized side which would typically be the charge pipe. If I did there would be other error codes stored and the drivetrain malfunction error would be persistent and not intermittent, Per the file I decided to test the vacuum lines from the head cover to the boost solenoid and from the boost solenoid to the turbo waste gate. I first measured the vacuum pressure in the trunk at the exhaust valve solenoid and compared it to the vacuum line going to the boost solenoid (bmw calls it a pressure converter part number 11747626351 for the 2011. it's been superseded for 2013 so check it on realoem.com). The pressures were the same at idle and as it turns out the vacuum line feeding the exhaust flap solenoid originates at the same point on the valve cover as the line feeding the boost solenoid. I then tested the vacuum line from the boost solenoid to the turbo waste gate actuator and it held vacuum just fine. I was really expecting this line to be bad based on what I had been reading here and other forums, but it was fine. This only left the solenoid itself. I tested the vacuum from the boost solenoid to the waste gate at idle. I did not have a T fitting, so I just used a spare piece of hose to the solenoid and left the hose to the waste gate off, and I did get a drivetrain malfunction. There was very little to no vacuum measurement coming form the hose to the wastegate at a high cold idle and when the idle lowered the pressure dropped, where I have read from others that the vacuum level rises at that point. This lead me to decide to replace the boost solenoid. There really is no great test for the solenoid that I found except this video which indicates there should be about 6 inches of mercury vacuum to close the waste gate. The signal to the solenoid from the ECU is a pulse modulated signal and there is no easy way to test it to see if it is operating properly. Mine was clearly not delivering vacuum to the turbo wastegate and was leaking vacuum enough to affect the exhaust flap and cause rattle.

Replacement was pretty easy except replacing the lower bolt. I cannot get that sucker on to save my life. The upper bolt is holding it fine .... I'll keep trying.

I have only owned the car since December so I really could not tell if there had been any power loss over time, perhaps if the solenoid fails slowly enough One may not notice it until these conditions start to happen. But it made a huge difference. The car idles more smoothly, and there is more power as the waste-gate now operates correctly to produce boost. No more drivetrain malfunctions and after undoing my golf tee mod, no more exhaust flap chatter. I then considered that if a failing boost solenoid could cause exhaust flap chatter that a failing exhaust flap solenoid could cause issues with the boost solenoid operation and that if one could fail so could the other. So I replaced the exhaust flap solenoid as well.

Step one for you I think is to read out your code before turning off the ignition to see whet you have stored. I read that I think before 2014 it clears automatically after each restart, but that after 2014 it stays stored and the code has to be manually cleared and the car stays in reduced power mode.

If you decide you want to test your vacuum lines and you dont have a tester, you can go to Advanced Auto parts and they will let you buy and return a brake bleeder / vacuum line test tool. You pay, in this case $73 for the tool and when you return it (they expect you will) they will refund the money. They have a large variety of tools you can rent for free, so long as you return them, which is great. This tool was a simple hand squeeze pump with a manual gauge for vacuum and pressure that you can connect a vacuum line to. With the engine running it will show your vacuum pressure and for the turbo waste gate with the engine off you can squeeze the hand pump to generate vacuum, which if the line is good should hold vacuum pressure.

Hope this helps.