I am experiencing exhaust problems with my 2004 Nissan Patrol when accelerating from standing/after decelerating such as coming out of a bend in. Whenever I do it, it expels black smoke and I lose power. This problem seems to be worse when the engine is hot. Cold starts do not present these conditions. I suspect it may be associated with the turbo in that excessive fuel, which has not been mixed with enough air leads to a super-enriched mixture going into the cylinders and the engine/acceleration becomes very sluggish. Continued depression of the accelerator results in a slow increase in speed (with black smoke) but then picks up with normal acceleration and no black smoke. It seems to run normally when travelling at road speed with no visible signs of smoke and fuel economy is normal (as measured before start of problems). I have some 445,000 km on the clock albeit I had an engine rebuild at 185,000 km. Any guidance you can give associated with what could be the problem would be appreciated.