Ok guys, here's my problem. I recently tuned my 6.5 up after putting almost 190,000 miles on her without even so much as a hick-up (new glow plugs and wiring, new marine injectors, heavy duty battery cables, new exhaust manifold gaskets, new valve cover gaskets and changed to a #9 chip).

All was well when I hooked on to a boat weighing in about 7500 pounds. Truck was running great when I started up a relatively steep hill the turbo was working and we were going strong when suddenly the turbo kicked out the temperature shot up and the truck went into limp mode. I managed to get everything off the road, unhooked from the boat, called a friend to finish towing the boat home and I went ahead and limped my truck on home. After much talking to local mechanics and changing everything that could cause the turbo to quit the truck is running ok but if I really put the fuel to it the turbo will just quit working. I need help. What is going on with this old girl????

 

Sounds like you are getting a high IAT defuel.

When pushed too hard the only way the ECM has to protect the engine is to dump boost.

You could get a turbomaster from Heath and prevent the low boost situation but gauges are a must.

Water injection helps,Aftercooler is also a good choice.

An EGT gauge is a must and no sustained EGT temps above 1200F.

Another problem can come from overboost so sustained boost above 10-12 PSI can also cause a defuel from a stock ECM.

Get the EGT and boost gauges installed and drive the truck within it's limits and if practicle get a intercooler/aftercooler or water injection installed to tow heavy.