Hello.

R56 MCS 2009 N14

First of all, absolutely no related codes are present... The car DOES sometimes go into limp mode, but not every time. All hoses leading to the turbo, air intake, cabin vent, and the hoses on the passenger side of the car (Left hand drive) are tight and secured.
The car drives absolutely fine, but the moment that boost would normally kick in, you can sort of "feel" and absolutely hear, the turbo/boost flutter, it technically has boost, but the moment you try to step on the gas, it just flutters so it gains no power. If you slowly speed up with the car, it will go as fast as you'd like, but the boost is not there. I have a short video that might help out. Reminder, this ONLY happens under load... You cannot repeat this while "driving" on the lift, this has been attempted, theres no good way to be up under the hood while its happening.

It had no issues, no air leaks, perfect boost until it was parked last year in September, it was parked most of the time indoors, but always on concrete the entire winter. Took it apart to re-do the subframe, and replace/upgrade bushings, install coilovers etc, now when its back together were seeing this air leak. :(

- Upgraded Wagner intercooler installed (Stole it off the 2008 MCS), did not test the 2008 beforehand, it had a misfire on cylinder 2 which wasn't diagnosed, so wasn't running properly beforehand unfortunately.
- Milltek cat-less stainless steel exhaust system, though probably irrelevant for this problem.
- Milltek cat-less downpipe
(The car ran fine with these upgrades for 5-6 months while driving regularly last year)

I have another R56 which is an 2008 MCS, and the same problem occurs, on that car I did have an Unmetered air code that I could not get rid of for the longest time, I do believe replacing the MAP sensor on that car did alleviate the code, but the boost/vacuum leak was still occurring.

Thank you!

EDIT: I uploaded the video to youtube instead of sharing the video file.

 

It definitely sounds like a small leak somewhere.
I would spray water (will drop rpm) or start fluid (rpm will rise) around every line/hose to find any possible cracks/leaks. I added small/thin zip ties to help seal all these lines. Clean MAF/MAP sensors. Check fuel pressure!
Then Id check and see if its the Diverter valve causing the issue.

 

Start here^. The diverter valve diaphragm may be torn.

 

I just replaced the diverter valve, did not fix the problem. Getting my hands on a smoke machine tomorrow, going to check to see if that helps find any leaks.

spraying water/starter fluid unfortunately did not help find the leak.

New, known good Diverter Valve

Old Diverter valve

Old

Old

 

Did you check the vacuum canister for leaks or cracks?

 

Where is that located? I remember putting it on the engine but haven’t looked at it at all. Looks like I might need to put it back on lift and look underneath to find that?

 

It's underneath the intake manifold. It would have been easy to crack during your subframe work. You may not have to remove the canister to test it, if you have a small hand vacuum pump often used to bleed brakes. Also check whether the two vacuum hoses attached to the boost solenoid (near canister) may have been swapped.

 

It looks fine from what I can tell underneath, but that doesn't really tell me much. Will need to take the intake manifold off in order to really check anything to do with it. I also felt around the boost solenoid and it has both hoses attached. Can't really see anything good enough to actually work on it without removing the intake manifold.

 

You could use a vacuum bleeder and attach it to the hoses and see if they hold pressure, or you can use a smoke machine...or take everything out and meticulously go over each hose.

 

Tested with a Smoke machine today, this thing is nice and tight.. no vacuum leaks. Starting to wonder if it’s something wrong with the engine 😕

It just makes no sense because it ran perfectly when last parked!!! Ugh.

 

Are you absolutely sure that the two vacuum lines connected to the boost solenoid (pressure converter) near the vacuum canister are not swapped and are not pinched?

With the engine cold, reach down and wiggle the wastegate actuator arm. Does it rattle or have a lot of play? It should be tight.

 

Do you think the boost pressure solenoid could be crapping out?

 

That's one of the possibilities. There are vacuum hose bypass tests that can be done to help pinpoint the problem component(s).

 

I mean it’s a little loose sounding but it doesn’t actually move much, it’s very similar to another R56 I have.

here’s some clips between our 2 minis

 

Does the rattling sound it makes when wiggled resemble the flutter that concerns you?

Do you have handheld vacuum that you can use to apply vacuum directly to the wastegate vacuum hose? If so, check whether that actuator becomes very stiff under vacuum.

 

+1 check the lines

https://www.northamericanmotoring.co...uum-lines.html

If its the Pressure converter you will hear a mooing sound.

 

Going to work on getting the intake manifold off tomorrow so I can start diagnosing… just bought a cheap vacuum pump/brake bleeder on Amazon which I can hopefully use to test the lines. Do you guys have suggestions as to how I should be doing it for the R56? I haven’t touched anything to do with vacuum so I’m a bit lost on what to look for… I understand how I’d test the lines themselves for leaks, but not sure otherwise.

thanks for all the advice, I hope this gets figured out soon!

 

also, the flutter is not just a sound… the car is losing essentially ALL boost when the turbo would normally kick in and pull. The sound perfectly resembles the sound like a clamp is loose and it is as if it’s shooting air out of the opening and then regaining pressure, over and over again. I was really surprised the smoke tester didn’t showcase an obvious leak…

after having wiggled it, I feel like this could be the problem that I am describing, but the problem with that, is, the other car does the same thing and has no issues related to boost.

 

Lastly, I have another entire R56 that is a parts car at this point and could hot swap anything I need to, to test to see if it’s the problem. Assuming the part in the parts car isn’t broken aswell. Reasonable to assume I wouldn’t be that unlucky… right? lol.

 

Do these two wastegate tests first.

Test 1
1) Disconnect the vacuum line attached to the wastegate.
2) Connect your handheld vacuum to the free wastegate vacuum nipple.
3) Set a timer for 1 minute but don't start it yet.
4) Repetitively squeeze pump handle until the pump's vacuum gauge reads 15-in of Hg. Do not exceed 15-in of Hg as it could damage the wastegate.
5) Start 1-minute timer and watch the vacuum gauge needle.
6) If the vacuum reading stays at 15-in of Hg for one minute, the wastegate does not have a vacuum leak. Proceed to Test 2.
7) If the vacuum gauge needle drops after 1 minute, then replace the wastegate actuator pod.

Test 2
1) With vacuum pump attached to wastegate nipple and holding a 15-in of Hg vacuum, reach down and try to wiggle the linkage arm and the flapper arm on the exhaust housing.
2) Under vacuum, they should feel rock solid. If they wiggle and rattle under vacuum, replace the turbocharger assembly for a new or remanufactured unit.

 

Ok I found a pump tonight and did those 2 tests, there is no vacuum leak and the wastegate lever does not have any rattle when under 15in of Hg vacuum. We tested all vacuum lines and the vacuum canister for leaks, there are NO vacuum leaks in this system. The only thing we cannot test, is this vacuum “boost solenoid” as I would probably call it? See image.

 

Just noticed this, could the intake manifold simply not being sealed tight be causing the issue? Seems charred/burned on the engine side of the intake manifold

 

Well… stayed up WAYYY too late, and still nothing. I just swapped the intake manifold with one from another R56 that was in MUCH better condition.

 

Based on all of your results, your enire focus should now be on the boost solenoid/pressure converter and its vacuum hoses.

1) Check whether the vacuum hoses attached to the boost solenoid were inadvertently swapped. The hose from the vacuum canister must connect to the boost-solenoid nipple labeled VAC. The long hose that runs to the wastegate must connect to the boost-solenoid nipple labeled OUT.

2) The short vacuum hose attached to VAC looks bent and deformed, which could potentially prevent canister vacuum from reaching the solenoid.

3) If 1 and 2 above are fine, replace the solenoid.

 

So coming from the Vacuum Canister, I did this twice now, just yesterday, so I know exactly how its routed.

According to several sources, the nipples on the vacuum canister are non-directional, so it doesn't matter where you put them? If thats the case, that doesn't matter, but these are swapped from the Diagram thats in this thread.

I currently have the following configuration:

Vacuum Canister 1 --> Vacuum Pump
Vacuum Canister 2 --> Short bent looking hose --> Small nipple on Boost Solenoid
Large Nipple on Boost Solenoid --> Turbo Wastegate.

There is pretty much only one way for these vacuum lines to go because of their length and hose size... There is only one hose that will fit on the large nipple of the Boost Solenoid comfortably, all of the other ones are way too small.

Note on the Canister 2 vacuum line, it looks bent, but it also looks like this in the diagram shown above as well, it must be like this from factory, it has all kinds of bends, likely to handle movement although its such a short distance... Definitely not a very intuitive hose lmfao. There is like 5x as much hose as necessary.

Sounds like replacing the Boost Solenoid is the next step still, just confirming how I have the lines routed at the moment.