wastegate fault maybe

[Knight Rider S4]

Was wondering if any guys here have had a wastegate failing (i.e diaphram,spring)and what was the indicators of the failing on a 3B

Have been looking at forum members car today and the fault is strange...slightly chattery noise when changing gear and loss of power

VAG.com the car for codes showed nothing
Did an output test everything working as it should including WGFV
Replaced DV as sounded like it was sticking(loosing boost) but this did not solve problem

Have checked all the hoses and they seem fine

The only thing it is seems to be pointing to is the wastegate

Cheers

[UrS4boy]

The first thing to do is open up the centre access to the waste gate spring adjustment and turn the spring perch down a few turns (2 or 3 , 6 max) to see if that makes an improvement. If it does, you could consider a 1.9 Bar replacement spring (with zero turns, all the way out). IF there is no improvement with the spring, the diaphragm can be replaced.

[newsh]

If the diaphragm is split, firstly you will get a boost leak through the small vent tube on the wastegate cap which will make a terrific whistling noise, secondly you are likely to get too much boost as the wastegate will not open properly. Unlikely that the spring is broken but easy to take the top off the wastegate and see, you can also check the diaphragm and check for excessive play in the valve guide while you're in there.

Have you tried taking the ECU fuses out of the fusebox for a few minutes clear the codes? Maybe its stuck in limp home mode.

[BRY]

if you pressure test it, the air will escape from the vacuum tube on the top of the wastegate if it's split. It did when I tested Topsparky's.

[Knight Rider S4]

Cheers guys great tips

[newsh]

When you undo the wastegate cap, be sure to hold it down as you release the last screw or it'll fly off and may do damage to yourself or a small woodland creature ..

[dm80]

Nice one Steve. It's as I suspected all along - a dodgy diaphram within the wastegate

Seriously though. I doubt changing the diaphragm and spring will be too expensive. It is displaying the symptoms mentioned above.. so I'll order them up and give you a shout soon. Cheers again.