That was the thread I read, did your problem start very slowly and become more frequent? I've got an issue where about once a month it'll just not have brake boost but I haven't noticed anything turbo related yet
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Yes it did start slowly. I first noticed something odd when at the end of the brake pedal stroke, there was an audible "click".
Brakes still worked fine, turbo worked fine.
Then it got worse, where in the morning when I went to start it with a foot on the brake, the pedal was hard. As soon as I started it up though, pedal went soft (like it should feel) and everything worked as normal. This lasted for a couple months like this. It was a sign vacuum was being lost overnight. Turbo worked fine though as the pump was putting out enough to fill the reservoir.
Then it started having the serious issues where I was getting the stiff pedal, and limp mode (no power). Brakes would come back for 2-4 strokes, turbo would come back a bit longer than the brakes. The turbo will always work a bit longer because that vac resevoir, if your pump can fill it, will provide vacuum to operate the N75 and N18 valves. The reservoir does not supply any vacuum for the booster. The booster is in direct line with the pump. Hence, if your pump starts having issues, the brakes will be your first sign, followed by turbo issues.
It was then I started that thread and employed pretty much all of the cheaper/free fixes until it led me to the worn out pump.