How to test a diverter D to know if its faulty?

[Sammy]

Recently i have been feeling reduced performance and MPG and i cant be sure but sometimes i get a hesitation when on boost so maybe diverter, How would i know if it is leaking boost or not?

[Thor]

You really need some one to scan with VCDS / do some logs. 

It may be that you have a coil pack on the way out.

[GrayMK5GTI]

Or smoke test it? All good tuners have the ability to run smoke though your boost system 

[Geoffcarragh]

when the rubber DV's fail you can hear a whistling noise (like air escaping from a balloon) when the turbo kicks in.

Easiest to hear the noise under hard acceleration in 2nd and 3rd gear.

Or you could take it out and have a look. this means getting under the car for the early K03 engines, but its at the top on K04 cars.

[GrayMK5GTI]

when the rubber DV's fail you can hear a whistling noise (like air escaping from a balloon) when the turbo kicks in.

Easiest to hear the noise under hard acceleration in 2nd and 3rd gear.

Or you could take it out and have a look. this means getting under the car for the early K03 engines, but its at the top on K04 cars.

Hard to tell on the Revision D DV as there's no rubber to burst and the leaks are more subtle (air escaping down the side of a piston).
VCDS logs are probably the best way to do it without taking it off and smoke testing it.

[Sammy]

What is the method of using VCDS to test a diverter valve, I know someone that has it but he's a total amateur

[ktlstar]

you measure boost pressure vs specified pressure will give you a hint, however if showing low could be many other reasons i.e boost hose leak.