Stumbled on something that I did not even noticed before in all my diagnostics.

Had a 1.8 Passat 20v. turbo in last week (petrol). Had a 'high fuel consumption' and code stored for lean condition.

Was looking at trims to get direction and did not see changes in long term fuel trim on EOBD (just maxed out on 25%), nor in VW software. In VW software it is even quite hard to find the correct data (channels) but that is some other problem (knowing what data you are exactly looking at). But then it came to me that this (for this condition I had) could not be right and checked directions on the VAG channels. I have too low numbers on a MAF (was oxidated as hell but after replacement it still reads only about 70g/sec on full throttle on  load, while the car is 150hp). So trims would have been a good guide.

This 'long term' and 'short term' for cars pre EOBD can fool you. This is is not short term, but 'idle' and not long term but 'partial load'. In other words,  you see idle and under load (above 1000 rpm) conditions but that may at times be a really different story as to short en long term diagnostics! In my case I could see that under load (partial numbers) were at 25% while idle numbers are ok, would you take it as short and long term, conditions were not that different idle and on higher rpm and that would give other directions (which might be wrong).