I have done it myself, but mine only had 17 000km of town driving when I bought it, why the hell did they buy a 159 2.4SW Ti to do town driving? We'll never know.
So my manifold was dirty but most probably not is the state yours is.
Here is how I did it.
I dismantled the inlet pipe from the after cooler to the engine, the one connected just before the EGR and the shutdown butterfly.
Then took a large seringe with or without needle makes no great difference, then reved the engine to 2000-2500 and squirted injector cleaner by 1/2 sec squirt directly in the the inlet.
I believe Bardhal is doing such product in a spray can. I used Tecflow speed cleaner, which has always worked wonder on dirty injector nozzles. 250ml of it.
It seems to have cleaned up the entrance of the manifold so I belive it did the same inside, at least the pressure sensor which was dirty, is now clean.
I am looking for a good boroscope now to go and investiguate directly inside the manifold to see how it looks.
I know companies do it, with a special device etc... but basically comes back to what I have done.
But if it is as bad in the pictures below, I don't know if my system will work, I doubt it very much
DIY clogged intake manifold cleaning VW TDI of carbon build up, 1998, 1999, 2000, 2001, 2002, and 2003
Here is a link for you.
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