156 2.4 JTD turbo noise & power loss
My 156 started making a new noise from every cold start a few months ago. Best way to describe it is somewhere between a whooshing noise and a distant police siren, not audible at idle but increasing in pitch with turbo speed. This got louder over time. It is accompanied by a lack of power at over 2.5-3k revs, but this seems intermittent and at (rare) times the car does appear to have full power. It is a 2003 156 2.4 JTD 10v 150bhp.
Only fault code showing is the common P0235, but the car has shown this code ever since I bought it a couple of years ago. The car has *occasionally* displayed a more dramatic lack of power over 3k rpm and accompanying temporary flash of the check engine light ever since I bought it, which I have never investigated other than to read fault codes. Whether this is related to the noise described above I don't know, although it has become significantly more common in the last few months. Engine runs perfectly otherwise although fuel economy is notably less good than it used to be.
I have read through previous threads regarding P0235 but none seem to mention the loud whooshing noise my car is displaying. So any input or heads-up before I start taking the turbo, EGR or MAP sensor to bits would be much appreciated. I wondered if it be as simple as a holed boost pipe, but this seems at odds with it sometimes appearing to run correctly.