Mk V GTI - loss of performance - leaking boost?

[Jonto]

Chaps

I have a mk V GTI and the other day i pulled out to overtake a car in third and at about 4,500rpm the car just stopped pulling as hard.

The turbo spools and sounds fine but the boost being generated isn't being tranfered into movement down the road.

The engine still runs sweet as a nut which leads me to believe there is a boost leak. Also, when i back off the throttle you don;t get the pppssshhhh noise anymore.

Does anyone have any idea? Could it be the boost controller or dump valve, split diaphram? Where are these located in the engine bay so i can look myself?

It's being to the stealers and the onlyfault code was one that said "max boost not being reached".

The reset the ecu and the code didn't come back, but my car is still the same. Pulls like a slug really.

Cheers Chaps

Jonathan

[RedRobin]

Sounds suspiciously like a failed Diverter Valve - They are a known weak link and VW are already on their third revision. Insist that your dealer inspects and if it is a DV it can be replaced under warranty....Or you can decide to get a Forge DV (see other thread here).

[Peskarik]

I, personally, would buy the one Forge makes.