D5 205 issue
 

I've a 2010 d5 205.Its at 100k and has full history.Coming form a shark performance ph2 xc70 I find the car a bit flat to the point that I wonder if there is something wrong.There are no reported faults on the ECU and it starts and drives fine although there is a hiss from the engine until about 2500rpm but then my old d5 used to be pretty vocal under boost.Ive check boost hoses on top of the engine and the inter cooler looks fine.Mpg is pretty poor at 25mpg but then I do small journeys just now.Could the car have a boost leak and not detect it ? Should I get a smoke test done at the garage as it just seems flat?

hiss
 

check the lower i/c pipe....mine was leaking a bit at join and i replaced the clip with a mikloor type,seems to pick up a bit better now
i do terrible miles /type of driving for a big diesel and get 33/34 mpg...its ex police[possible polestar type map] and manual though...

I did check, adjust and tighten the lower boost hose where it goes onto the alloy pipework.Ive had it smoke tested today with only a small leak showing on the intake pipe as it joins the lower pipework.Its not made any difference but oil muck can be seen underneath where the turbos are.Getting worried now but I might get new pipework and seals ordered but informed it's a pig of a job.! Drove another d5 205 xc70 today and it doesn't his like mine and is quicker.

Gunk
 

If there's is gunk on the outside, I wonder what's inside trying to get out. Maybe your turbo vanes are clogged? That could account for lack of power/boost?
Might be worth checking the movement, i.e. is there full movement on the actuator arm.

I take you've had a peer inside the throttle body in case that's clogged up?

I've not looked inside the throttle no.ill do that and see how choked it is.I didn't think the twin turbo had variable cane turbos? I think I've identified it as a leak from the orange seal where the pipe meets the turbo itself.

I have the same issue with my 59 plate V70. I’ve not started investigating yet but am only showing in the system an average of 28mpg. I was concerned as I had a non polestar remap for about a year before having it removed as I feared it could have been responsible but the mpg remains poor. In addition the auto box is now very rough when switching between gears, I can only describe it as between cogs it is sustaining the revs but then occasionally really thumps in to the next gear. I’m contemplating a go on a vida diagnostic but can’t afford if ( probably due to how much fuel I’m having to buy!) for a month or two.

How many miles do you have? It's worth getting the transmission fluid changed as that'll hopefully fix the thumping before the gearbox gets particularly upset.

Volvo say they're sealed for life but other manufacturers that use the same gearbox suggest 30-40k intervals for changing it. Mine was like a new box when I had it done.

The car has just passed 110k. I’ve seen YouTube videos on that subject and thought it might be worth a go but was surprised to not see many mentions of it on this site. I also meant to say that it only happens when I’m driving cautiously or with mechanical sympathy never when in full acceleration but the little rug rat diverted my attention. I’ve had the car since 80k and it has a tow bar fitted but no obvious signs/marks to suggest it was used for any significant towing. It’s good to know someone who has had it done and rectified, perhaps it’s not linked to the remap/mpg issue after all.

No , volvo have never said that , there are schedules suggested by volvo too as well just like those other manufacturers every 36000 miles if the car is used as a taxi or used under "Arduous" conditions ...or if you just want it changing , I don't think it is mandatory on any manufacturers service schedule , they all want to keep the cost of servicing down to keep the lease companies happy ,It will increase the cost of the alternate services a lot of course.
With the recent new Volvo service schedules of the last 4 years or so you can tailor your service to suit your needs , You and the service advisor need to be on the ball though. What is equally important is having the latest software , it is always being tweaked .
Thumping into D or 5th to 4th from about 2013-17 is known by the dealer they have a few bulletins to guide them on this the easiest is a re-adaption and software . .

Clan,your bound to know the common boost leaks on or between the turbos? Looking up the back of the engine there are two black plastic pipes.One has a sort of resonator on,the other is smaller.Are they bad for leaking on these? I just cant see up there even on a lift! I've changed a few xc90 d5 black turbo pipes when they crack and I wondered if this was similar? When speaking to Strathmore Volvo they commented on replacing the orange seals ?