Thought this would be worth sharing.

My 2 litre TFSI started developing flat spots. I presumed it was because my wife wasn't driving it hard at all. It progressively got worse, to the point it wasn't boosting properly until around 5k revs and sometimes not at all. So I nipped it across to jabbasport for them to take a look.

They took it out for a spin with the laptop and sure enough, it was requesting the boost but not getting all of it. Straight away, they said it was the dump valve. And they were right! Popped a S3 one on as its a more reliable variant and it's back to normal. It's like a brand new car. Must've been poorly for a while.

For 90 quid, I couldn't be any happier. This will hopefully help someone out at some point. Saves all the trial and error.

as a diesel car owner could you explain the dump valve thingy for me?

I've just baught a new revision G as my D doesnt seem to be working great. I get lots of turbo chatter when i rev it quickly as if the valve cant open or close quick enough. Hopefully i'll get it replaced this weekend if the weather is nice. Its such a PITA to fit though :/

as a diesel car owner could you explain the dump valve thingy for me?

It releases the turbo pressure when letting your foot off the throttle, if it's faulty (i.e the spring gets weak with age) then it releases pressure all the time hence no boost and poor performance.

 

the VAG diesel doesn't have a dump valve, the VNT mechanism on the turbo serves the same purpose.

I take it dump valve is just another name for diverter valve?

 

How difficult a job is it to replace and where is it located?

Yes mate, it's the diverter valve. It's located on the turbo with is low down at the back of the engine, so a pain to get to. But its just an electrical connection and some bolts. Easy enough when it's on the ramps.

Thanks. Mine is getting of an age and develpoing a few flat spots during acceleration. Hopefully a new DV will fix that.