Pisssssh noise when accelerating

[Nellielou]

Mk7 2008 rwd 2.4 tdci. When driving on main roads at approx 40/50 mph and I go to accelerate, I hear a pisssssh noise, take foot off accelerator n noise stops,put foot back on and maintain speed,no noise, put foot down harder n noise returns.Cant see any leaks from underneath.any help appreciated

[knobby1]

Mk7 2008 rwd 2.4 tdci. When driving on main roads at approx 40/50 mph and I go to accelerate, I hear a pisssssh noise, take foot off accelerator n noise stops,put foot back on and maintain speed,no noise, put foot down harder n noise returns.Cant see any leaks from underneath.any help appreciated

More than likely a boost leak...check all boost pipes/hoses, intercooler and inlet manifold for leaks or splits.

Lord Knobrot