[mwebb]

Originally Posted by cRiPpLe_rOoStEr

Sure. On a sidenote, makes me wonder how water injection would affect both the particulate matter buildup and the regeneration process.

watch out for thermal shock
on early VWs of the mark 4 vintage the heater on the AFR or 02 sensor does not get switched to on
until
after
the car gets to 50mph or thereabouts AND coolant temp crosses a threshold the value of which is not released to the mortals
to
avoid
thermal shock of the thimbles in the AFR / 02 sensors
on the theory that there will be no liquid h2o in the exhaust stream , it will all be in vapor state due to the heat / temperature in the exhaust

you do not want to crack the substrate in the DPF or the thimbles in the lambda sensors

so
no
you should NOT use water injection in any TDi or ever

imho

and
EGR is good
more EGR is better than less to a point and defeating a properly function ing EGR does not improve fuel economy or power as
EGR does not operate at high load anyway .

carbon buildup is mostly caused by the driver AND bad fuel
also
imho

current VW diesel tech
the opinions expressed are my own

i own 2 mark 4 golfs with BEW and 5sp
average hi 40s on both
less in colder weather
43psi on tire pressure
one has 225 45 17 continental tires
the other 205 55 16 michellin tires