hi,
for over 6 months now our multi (2004 1.9jtd 115bhp) has had an engine management fault & thus goes into limp mode.
car drives great with good turbo pull up to approx 3000 revs- then
light comes on.

using fiatecuscan the error code is always P0236 -turbo overboost valve -
little or low pressure signal to ecu.

i have replaced overboost valve, tubing, maf sensor, map sensor,
cleaned egr and very recently used innotech turbo cleaner to clean
the variable vanes on the turbo.

one thing i have noticed is that while stationary (and with the error cancelled out using ecu scan) the car will rev to 4000 plus revs without
management light coming on at all- so light only comes on at approx 3000
revs while actualy driving.
Also while stationary car idles and revs perfect & smoothly up to approx 3000 revs, but then definately "STUTTERS" as it progresses up to 4000 plus revs.

SO... this stuttering, like fuel related is clearly no coincidence, so has
anyone got any suggestions at all?, if you have any thoughts, please
advise.

Car runs and pulls great with good turbo pulling power up to the 3000 revs, its a lovely car, just pretty much undrivable as no turbo once light
comes on, making driving unsafe really.

car now has full 12 months mot (2 brocken front springs replaced), is
insured, just waiting to be taxed as soon as fault is remedied!.

There must (obviously) be something i have missed/overlooked....

one thing i forgot to mention is the large plastic corrugated pipe (breather?) going from turbo is pretty oily, could this have a leek in it? be the problem?
could the front springs collapsing have caused this pipe to split at all (hard to tell if it is due to its rippled structure and oil)
any advice?
are these normaly oily?

meant leak lol