Hi,

I recently swapped out my vacuum pump on my N14 r56 and been getting the "Bost-pressure control deviation, plausibility" code. Didn't have this issue before and swapped the vacuum pump and changed the thermostat and water pipe. I will only get the code when I hit about 4k RPM, otherwise it's ok. I rechecked all the vacuum lines on the wastegate as well as down below the intake manifold and it all looks ok. I only did a visual with all the lines and it looks ok to me. I also pulled the blowoff valve to see if there were any issues and it looks ok. When I don't have the code, I can hear the whoosh of the blowoff valve. Reading the boost psi front the ECU I'm only seeing about 6psi. Is there anything I should check. Think I need to check the wastegate totally closes, but I need to get something to pull a vacuum and get a endoscope. Is there any reason why I would need to adjust the wastegate settings when going to a new vacuum pump?

 

Please post the BMW fault code(s).

 

Main code is 2885. When I clear it, all others will clear and stay cleared until I create the scenario when I hit about 4k RPM.

 

Start by carefully looking for a disconnected and a cracked vacuum line that loses vacuum.

https://bmwfault.codes/Lookup
Service notes for code 2885:

 

Ok thanks. I visually checked all the vacuum lines. I've heard you can look for collapsed lines while engine is running. From the sections I can visually see they look ok, but it's tough to see all the lines. Is here a way to check them dynamically? Could I use a handheld vacuum pump to pull vacuum and better check those hoses? I know there's a solenoid down below the reservoir, not sure how to check that functionality.

 

Just wondering why you changed the vacuum pump in the first place? Was the car operating normally and boosting normally prior to the change?

Double check all the new connections again. Once I had an issue after changing a valve. The very experienced BMW/Mini specialist shop that did it had embarissingly connected the lines up incorrectly,.

 

Had 130k on the original pump. Pump failure could cause severe internal motor damage if it seizes. It connected directly to the exhaust cam.

 

Does the pump have a vacuum gauge?

 

I can read the vacuum electronically via the ODB port. I don't have an actual gauge. I don't recall what the vacuum pressure was before I swapped the pump, but I'm in the 22psi range of vacuum and have only seen 6psi of boost. I'm pretty certain I was at least 10psi of boost before.

 

Boost pressure and vacuum are different.

You mentioned that you have a handheld vacuum pump, which could be a valuable diagnostic tool for your issue. What handheld pump do you have?

https://www.harborfreight.com/brake-...kit-63391.html

 

I don't have one, but thinking this is my next step in diagnosis. I see how to confirm the wastegate, but is there a way to check all the other vacuum ports?

 

Pull the small vacuum line off the nipple of the new vacuum pump. Connect your handheld pump with gauge directly to the nipple using a tight fitting adapter.

Start the engine and let it idle.
You should read 25 to 30 inHg immediately.
Anything below 20 inHg means the pump isn't working properly.

There are other tests to do later if the vacuum pump passes the first test.