Volkswagen Repair: VW Beetle turbo not working, mass air meter, vacuum tester

Question
I have a 2001 VW 1.8 turbo Beetle.  The turbo was surging and has now quit altogether, I can't even feel the turbo at all, not even the surging.  I replaced the turbo bypass valve and that did not help.  What else could cause this?

Answer
Well a loss of power does not mean the turbo is not working. It may just mean that the vehicle is in limp mode. Meaning that the engines computer doesn't know how to run as designed. If the check engine light is on then the fault needs to be looked at. Most of the time the likely causes are the mass air meter and the throttle body. Either one of these can cause no power. If there is a major intake leak then that also will have the same symptom. If the reason is really the turbo then the wastegate solenoid valve, Turbo by pass valve and turbo need to be checked. You need a vacuum tester and place it on the turbos waste gate  vacuum hose where the hose goes to the turbo. Connect the vacuum tester to the hose and see if you have vacuum at idle and then step on the gas and see if the vacuum changes. If it does then the solenoid and hoses are good. Unplug the mass air meter and see if you have power then. This will turn on the engine light. The best way to diagnose this problem is with a scan tool. With out it your just spending a lot of time making checks that are hard to diagnose. Good luck.