I'm at the end of my rope with this car!
I have a 2016 Clubman S with 102k miles on it. The turbo went several months back. I replaced the turbo with one from a salvage yard. The salvage turbo had 50k miles on it. After replacing the turbo I was still getting an error (boost pressure below threshold).

Shortly after this the computer went nuts and started throwing codes for numerous sensors. The car wasn't even driveable. I had it towed to Mini and they said they would have to reprogram the ECU. They also smoke tested the intake and found 2 small holes in the intercooler. 1 After that the car was back to the same as it was before the computer issue. Still no boost. I replaced the intercooler with an aftermarket bolt-on model. Unfortunately, I was still getting the same error. I then replaced the pipe from the turbo to the intercooler. Still the issue remains.

I bought a device to allow me to pressure test the entire intake system. I was able to put 8psi into the intake right where the air filter box would normally connect. While I did this I was checking the reading from the MAP sensor which was showing 22.5psi. Which to my knowledge, that would be correct. 14.6 is ambient air pressure then I added another 8psi on top of that.

About 3-4 days after getting my car back from the dealership, all of a sudden, the car started running perfect again. It ran great for about 2 weeks. Then, for no reason I can explain, the boost issue was back.

I brought the car back to mini. They smoke tested again and pressure tested but they weren't able to find any leaks. The technician said he believes the wastegate actuator was bad. Unfortunately, you cannot purchase this part on its own.

So, I purchased a brand new turbo for just over $2k. I installed the new turbo today, took it for a test drive and..... You guessed it, still no boost.

​​​​​​​I'm about to set this thing on fire!!!

 

I have a reasonable suggestion:................ GET A NEW CAR
You've already thrown away a few grand. Cut your losses already. That 2016 car was probably worth about 9-10 grand on a trade-in when it was running good.

 

Quick question, are you running any aftermarket parts such as a Dinan Sport Tuner, or is your car, except for the replacement parts, stock?

 

Everything except the intercooler is stock.

 

Not really an option for me at the moment.

 

OK, so if anyone else out there is having a similar issue, I think I might have found the problem.

When the computer went haywire and had to be reprogrammed, it melted the catalytic converter. I removed the little bit of the cat that was still remaining to make it hollow. I found out today, that this car has a secondary catalytic converter. It appears as though the pieces from the primary catalytic converter that broke off, have become lodged in the secondary one. Tomorrow I will hollow out the secondary one to see if that resolves the issue. If it does, I will be purchasing a whole new exhaust from the turbo back....

 

A plugged exhaust will certainly prevent the turbo from spooling up and therefore no/low boost. Hopefully hollowing out the 2nd cat proves a solution and you can move forward. Good luck.

 

What an ordeal!! Can I ask what intercooler you installed?

 

The two-week period where it ran normal, then went back to low boost makes me think it is a sensor/actuator and not mechanical. Clogged cats tend to slowly fail or rattle upon failing, and once they are bad the symptoms do not improve until their fixed.

Have you tried resetting the Engine control module by unplugging the battery?
A live data viewer would be very helpful to monitor the sensors.