Testing a 2013 Mini Cooper S Wastegate. Dealership claims it is a bad turbo, however, the car drives great and pulls hard. I get a check engine light when coming off a stop light. Can't read the check engine code. At 10" of vacuum the wastegate is sealed tight. The wastegate seems to stick if I release the vacuum pressure quickly. If I release the vacuum slowly, the wastegate releases smoothely. Is it bad wastegate or bad wastegate actuator.

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If you have a code, I would get that read ASAP, as this will direct your efforts much better than trying to throw logic at the car.

I would expect a bad actuator to leak vacuum. Yours seems to hold it pretty well.

I would expect a worn shaft in the turbo housing to either be sticky or lose.

Think about normal operation on the actuator. The engine has a vacuum pump which creates a vacuum on a receiving tank. There is a solenoid that either adds or removes vacuum from the actuator. The wastegate is either open or closed, nothing in between. If you remove vacuum and it sticks, you’ll get a fault.

 

I tried pulling the code but my code reader did not find any despite the check engine light. Also, the check engine light was only on the tachometer. Not on the center dash.

Update:

I realized that I was closing the release valve on the vacuum pump with my finger causing the jerkyness of the wastegate. I also removed the diverter valve and found a 1/2" tear in the diaphram.

 

Sounds much better than having the
stealership replace your turbo on your
dime unnecessarily.
(“... oh, and we put a new diverter
valve in gratis, ‘cause it was old anyway.
Runs good with the new turbo, don’t it?”)

 

Time to invest in a Foxwell scanner?

The diverter valve was probably your issue.