Nissan Terrano II

Pepper, if the crud accumalation is in the intake manifold it won't be from over-fueling because the diesel is injected under pressure either into the combustion chamber in the case of direct injection or pre-combustion chamber in the case of indirect injection.
The only thing in theory which is supposed to enter the intake manifold is clean filtered air compressed by the turbo.
What I suspect you're seeing is oil, either drawn through the oil seal on the turbo or from the rocker cover breather tube where it enters the air intake system upstream of the turbo. I don't know if these engines have a PCV valve but that could also be a problem if it's stuck open.
Your best way to check is to remove the tubing from the rocker cover and PCV tubing if it has one at the end where they enter the air intake and check if there has been any obvious signs of oil going through the tubing.
Any oil in your intake manifold has to have gone through your intercooler and it will also be very badly contaminated and need to be cleaned out. To clean the intercooler you should pour some petrol in it and just shake it around then drain it. Keep on doing this until it runs through fairly cleanly then set it aside in a warm dry space outside if possible and allow the petrol to evaporate. If you're concerned about the petrol fumes you can use methylated spirits after the petrol as it has a less combustible nature.
At no stage should you install the intercooler unless it completely dry of fuel!!!!
Regards Andrew.

Oxygen sensor can mean a few things. In a petrol, it is on the exhaust manifold and reports to the computer whats happening, on a electronic injected diesel, it could be in the intake down from the filter and measure temperature or flow, not sure, but with some new cruisers, you cant use an oil/foam filter in them or it will coat this sensor with oil mist and shut down the motor.
What you are seeing in the intake is normal for a turbo diesel. When you say overfuelling, what do you mean? tell us whether it is using too much fuel, down on power, starting cold runs erratic, smoking, colour of.. etc etc.
Andrew wheredayathinkwer mike?

Dozer, if as Pepper states there is about 1/2 an inch accumulation of muck in the intake, I would be most concerned. It certainly doesn't sound like normal wear & tear.
Pepper, when you say over-fueling. Is it blowing smoke, either blue or white? Or is the engine running on after shut down. If it's the latter then you may have a problem with the engine running on its own oil.
Regards Andrew.

I just had my Terrano 2 2.7 TDI dyno tuned, they achieved a 22% increase in horsepower, mainly by cleaning the air flow sensor!

Pepper
Airflow sensor!!??
Just got to find out what the cleaning fluid is.
Check out the post re: snorkel.
I'm off to Bribie this weekend with the boys so I won't see you.
Cheers
OskarMrs Oskar on Big Red

The air mass meter is located in the duct just down stream from the air filter. The meter can be removed from the duct with a star type screwdriver and given a good spray with contact cleaner.
Mine was totally stuffed, so I went looking for a new one and nearly fell over at the price Ni$$an were asking. BOSCH makes the part, and being good Germans that like to keep track of everything, there is a BOSCH part No. On the side of the duct that the air meter in screwed into (4 bolts hold it onto the air cleaner and a hose clamp to the turbo duct). Take this number to a Bosch auto electrical/fuel injection shop and you will get the part for around $400, not good, but better.

Nissan say the fuel injectors have to be bought as a complete unit (around $2000 a set), but you can get Bosch nozzles (original part anyway) for fitted and pressure tested for around $300.

Sounds interesting. What brand did you buy and how is it used? Do you run the moter after you poored it in for a while or just a view minutes then change the oil?
Thanks for your help, will get on to that tomorrow.
Cheers
Andy