As far from JBS as possible !
I take it you are talking about a diesel engine of some sort? Sounds like turbo/EGR related sort of thing so best thing to do would be to remove and clean the EGR and go from there.
06 Audi 2.0 PD140 Sport TDI Quattro S-LINE.
Old engine 330 bhp @ flywheel 263 bhp @ wheel 490 lb torque.
Audidriver write up HERE
Now stripped and playing with an uprated Cryo treated engine fitted with bigger turbo,water/methanol,uprated injectors etc etc.Wanting 400 bhp and 500 lb torque.
Other car 500+ bhp MK4 Golf R32 turbo