[335DEE]

Lots of people having issues with power problems and lots of different types of fixes to resolve these problems ( Red hose , vac hoses , pressure converters etc etc ), but no one has suggested a leaky diverter valve.

If there is no diverter valve then how does the charged air get dealt with on throttle lift when the system is on boost ??

[HighlandPete]

The 335d has a turbine control valve and a wastegate.

Turbine Control Valve
The turbine control valve opens a bypass channel on the exhaust side to the low pressure stage (past the high pressure stage). It is operated pneumatically by a vacuum unit and can be variably adjusted. An Electro-pneumatic pressure converter (EPDW) applies vacuum to the vacuum unit. In development, the turbine control valve is referred to as the main control valve.

Wastegate
On reaching the nominal engine output, the wastegate opens to avoid high boost and turbine pressures. A part of the exhaust gas flows via the tailgate past the turbine of the low pressure stage. It is operated pneumatically by a vacuum unit. The wastegate can be variable adjusted.

HighlandPete

[335DEE]

How very thorough ! . I'm interested in the

Originally Posted by HighlandPete

The turbine control valve opens a bypass channel on the exhaust side

and where or what this device is and if it is possible to service or replace.
I have just renewed the EPDW's and vac hoses but do not think this bypass channel is opening correctly. Slight turbine chatter on lift off especially when cold and a "CHAIO" sound , also spooling up doesn't quite sound right ( no nice smooth sounding hiss increasing in pitch ) sounds more hollow is that's a good word to describe. BTW this isn't pedal to the metal stuff , but very low revs and slow speeds.