Pair of TAMD72Ps low on power

[wpenner]

I am working on a pair of TAMD72s that are low on power. Apparently one engine has been lower on power for a long time. Recently the other engine started loosing power as well, and then from one use to the next now both don't make enough power to get on plane. With both engines in gear and full throttle the better engine makes 1500 RPMS and smokes some as if it trying to push and the other makes 1200 and no smoke. Turbos are tight and do make some boost - haven't checked psi yet. Fuel filter have been replaced on both engine and fuel supply has been check good to the engines. My feeling is there is something causing the computers not to increase fuel to WOT. Sort of as if they could be in safe mode?? But no fault codes. What should my next checks be.

Willie

 

[luptonj]

Are you sure the "Good" engine is low on power. Could be the bad one has gotten worse so the good one is no longer able to get the boat on the plane.
Or more fouling etc making it harder to get on the plane, the good engine can only rev so high if the boat isn't moving.

 

[wpenner]

I agree and was thinking the same thing. But according to the owner before the power issue started, both engines would have reved to 1800 rpms under the same scenario. One idling in gear and the other at full throttle and vise versa. ( When I said that one engine was low on power a long time, it was not that much 200-300 rpms lower on full throttle.)

 

[oldgit]

Does each engine achieve correct high idle RPM at WOT.
ie Not under load.... 2600.?
Are props clean of crustations presume no "expert" been messing with the prop size or pitch. ?
Club member was recently reduced to 12 knots on his Princess 41 with 2 x 385Hp diesels simply due to barnycules on prop blades.
Diver sent down with a scraper and 26 knots back on the agenda.

 

[volvopaul]

72 and 72 p version not a great engine.

The double housing intercoolers clog up with oily deposits rendering there ability to cool the inlet air difficult blocking its path .

The turbo is a wastegate version bolted to some kind of box that corroded away .
The wastegate could be leaking causing boost to slip by into the exhaust rather than the fan .
The boost sensors in the ecu could be faulty .

Do you get black smoke ? If not no fuel , could be sensors .
Back to basics of supply first then look at sensors , wastegate and inlet fan for damage.
Corroded intercooler housings and displaced o rings all make up for loss of boost pressure .
Employ local dealer with diagnostic key to sea trial boat , if there any good they will tel, you what’s going off .

What make, year and model is the boat ?
Is this your own boat or a clients ?

 

[wpenner]

Blackfin 35ft. Not sure of the year. It is a client's boat.
Unfortunately there is no dealer here in Belize for Volvo Penta. I am good at diesels engines both manual injection and electronic, but without having any diagnostic hookup for these engine I am a little in the dark. I wish I could hook up a diagnostic scanner and see live sensor data.

The intercoolers have been checked/cleaned since the problem with no change - they were not really dirty. Turbo boost pressure is one of the next things I will check - I know there is some boost, but could be not enough. One engine is smoking some black after 10 seconds of full throttle which I say indicates ecu is seeing at least some boost. The other engine does not smoke any at all. If there was a faulty sensor the ecu would throw a fault code I would believe. Now yes there is the possibility that a sensor is skewed to the point ecu doesnt pick up a fault as well as not receiving correct info and limiting fuel/boost? I am thinking to swap ECUs and see if the smoke will follow the ecu, in that case I would point at the sensor in one of the ecus. Any other suggestions?

Thanks for all the input so far.

 

[wpenner]

Free reving in neutral, one engine attains 1800 rpms, the other 2100 rpms. Props were cleaned even though they were not very dirty. Same props that worked fine till recently.