Volvo TAMD 75P top rpm issue

Hi
I have a Princess P42 with 2 TAMD 74P upgraded when boat was new to 75P. Engines have run whiteout almost any trouble. History on engines says that there was a loss of top rpm on port engine back in 2015. Report from mechanic back in 2015 says: Ran the engine whit fresh fuel from can, problem the same, exchanged boost pressure sensor with starboard engine, problem stayed the same. Wastegate removed, cleaned and function testet, all good and the engine reached 2600 rpm.

In february this year I had the first trip of the year,and could not get it past 2050 rpm's on the port engine. (when the boat was in layup in october last year everything was fine. ) After layup I changed all the fuel filters, both the separ filters with 30 micron filters as usual, and the 2 spin on on both engines. Original Volvo filters used as always.This was probably november 2023, and the separ filter to the engine with the trouble have been lifted up, and is still white and not clogged. I noticed that the air bleed valve on the Separ filter to the port filter was only finger tightened, so I bleeded the filter and checked for air on the bleed valve on port engine after i discovered the problem, but that did not change anything.

I checked the boost pressure line, there was some condensation in the T before the boost pressure sensor on both engines, drained it, took a test drive, same problem.

Then I changed boost pressure sensor between the engines, problem stayed the same. 2050 rpm on port engine, starboard engine runs up to 2400-2450, probably because the port is not pulling its weight. I have NO SMOKE, but I feel there is a little more soot on the stern during long hauls.

Took out the waste gate on the port engine, it did not function as it should, stuck closed position and did not popp as it should when pulsed with pressure. Got it moving by crc (WD-40) and repeating its movement. But did not have a good feeling as when it layed on my workbench it seemed to get stuck again, but i put it back in, test-drive, issue the same... Ordered a new waste gate as I was sure this was the issue seen in symptoms and history of the engine, test-drive, but still can not get more than 2100 rpm's. I think the increase in 50rpm is due too less fuel and water onboard. I have also checked the seat for the waste gate inside the turbo housing, and the condition is good, and it seals as it should.

I have not measured the fuel pressure, or the boost pressure. I have no fault codes on my EDC, and my local volvo pusher have not got VODIA for reading of live data. I´m out at sea for work now, so I can not test more before I get home in April, but I was hoping some of you guys have experienced the same and can point me to the source of the problem

Engine hours is 1700 Hours, have checked the turbo by hand, and it speeds easy and freely, and no signs of metal touching metal on airside. Have not inspected exhaust side.

As

As I wrote, testing of the wastegate was done because of know’n history of it beeing the root of the problem back in 2015. I was on winter holiday when I discovered the problem, and did not have much to help me with regarding the pressure messurment. No pressure gauges for reading the values. That is my next step when I get home from work, and I know that it is the place to start, but i was thinking that with so many of theese engines around the world, someone may have had the same issues Often the fault is minor, and maybe somone had a good tip Thank you for the input