Not sure if this is where I post for this repair but, I have an 09 JCW, I'm getting the 2885 error code (boost deviation plausibility). First place I checked was the diverter valve thinking the boot inside was cracked/destroyed like many of you have encountered. Boot is fine but the black "tophat" looking thing lol that covers the rubber boot is brittle n starting to chip around the sides but still works. Added a forge BOV adapter and I can hear the Whoooosh sound more, so, I don't think that's the source of the deviation. My next trial is replacing the vacuum lines because when I get on it, I can get through all the gears fine 5000+ rpms except once I go from 5th into 6th my limp mode light (half yellow engine) lights up. I will say that on start up in the morning during cooler temps this is not really an issue but once the day heats up my half yellow engine light will display and sometimes it will light up from 4th going into 5th so I'm thinking my vacuum lines are getting soft n collapsing.
my question is, does anyone one know the size of the inside diameter and how much vacuum line I should buy. I want to go with aftermarket maybe from ECS tuning they have forge vacuum line for sale. Sorry for such a long post just wanna be thorough.

 

I would replace your vacuum line with the MINI assembly - would not go with just generic line.

Be sure to search this forum....and check out -

https://jmtcperformance.com/publicat...ibility-error/

Lastly, I went through what you're doing on a car with about 120,000 miles on it and it was my wastegate.

 

Yes that's another obstacle I was considering may be the issue...I to have about 120xxx on the dial a little less. However, I do have a warranty that covers the turbo so I was thinking about droppin it in the garage and having them check it out and hopefully replace the turbo. I do want to replace all the original parts though just so everything is brand new... Just got done replacing the oil filter housing n cooler gaskets boy that was fun lol learned a little more about the car though. Thanks for your advice/input brother much appreciated.

 

Just got this same error on the drive home yesterday. I have noticed previously the car will boost well but then start to fall on its face even though I am at full throttle. I have ordered a new OEM diverter valve to replace mine since it is fairly easy to replace and not super $$$. While I am in there I will check over everything to look for leaks and also inspect the wastegate actuator to see if it is still good. Hopefully this turns out to just be a blow diaphragm on the diverter valve.

One thing I am a little concerned about is my oil catch can. I installed a GTT vacuum side oil catch can about 1000 miles ago. The unit is well made and does not appear to have any leaks but it is plumbed into the intake manifold and subject to boost pressures. If it does leak that would be a direct boost leak which would cause this code as well.

Also, I was surprised when I pulled up the code on Carly. You can see the screen grab below. A couple curious things stand out.

1. My Mini has around 76k miles on it. Those codes state they occurred at 60586 mi.
2. The target boost pressure is at 29.59 psi. That seems enormous! Is that really what an N14 JCW engine runs at?!? I guess one possibility is that that value is absolute pressure (includes atmospheric). If you drop off standard pressure of 14.7psi then it works out to just under 15psi which seems more reasonable.

 

Just an update, I replaced my diverter valve over the weekend and the results are promising so far. Boost appears to hold well and the engine doesn't fall on its face at 5500 rpm like before. I inspected the old diverter valve and the rubber boot was not torn and looked okay. The new valve is the newer design used on the N18 which does not have that boot. The guy at the Mini dealer was a little confused when I ordered it as it was not listed as compatible with the N14 but he ordered it anyhow. $70 plus tax and I am back to motoring. :D

 

Sounds like a good news story.

 

if the catch can that’s connected to the intake leaks you should have a vacuum leak, not a boost leak.

i ran to thin of hose when i first installed mine and it would collapse from the vacuum once the PCV valve closed

 

Actually you would have both. The PCV check valve is in the valve cover, not the intake manifold. That means the catch can will see both full vacuum as well as full boost pressure. Basically, this circuit will see whatever pressure is present in the intake manifold. That is why a catch can on this PCV circuit is so tricky to design and get right; the requirements are much more complex/stringent.

 

If there are 120K miles on the turbo, then the waste gate is likely total junk. I've pulled 4 MCS turbos apart to date - all have had junk or near junk wastegates at mileages between 75k to 105k. The shaft bearing is typically in great condition with high miles. The trust bearing is almost always badly worn @ 100k. Bearing condition correlates positively with a lack of oil deposits in the bearing bore - so it seems like frequent oil changes are good for turbos.

The wastegate actuator travel should be checked and adjusted periodically as the linkage will wear over time. Wastegate actuator travel effects boost - longer travel -> lower boost.