My multiplicative fuel trims (A4 V6 30V) seem to always be on the rise these days! Using VAG-COM/VCDS measuring block 32, my idle/additive trims remain consistently at low normal levels, partial/multiplicative just keep increasing negative! Bank 1 is always much worse than bank 2 also, although everything is always on the negative side. Currently, I have -15.6% on bank 1 and -7.8% on bank 2 (both are multiplicative).

Here's a summary of everything I've now done with the car so far to try to address this problem, each unsuccessful:

1) Full tune-up: fuel filter, coil, wires, spark plugs.
2) New OEM Gas cap changed
3) MAF changed
4) Vacuum lines changed
5) Engine coolant temp. sensor changed
6) Fuel injectors swapped between banks, and 1 new fuel injector installed on the more troubled bank (bank 1) too. No change in the pattern.

My short-list of remaining things which might resolve this too rich problem (oh joy!), not sure what order to go next:
- Fuel pressure regulator
- Spark plug gap (shouldn't be bad because it is new & professionally installled)
- Spark plug wires (shouldn't be bad because it is new & professionally installled)
- Compression test & possibly valve/valve gaskets
- Oxygen sensor.

The basic symptoms are, following a computer reset, multiplicative fuel trims continually become more rich each day, while additive trims remain normal. Bank 1 is always more rich than bank 2, usually by a factor of 3:1 to 2:1. Both trims do rise however. Fault codes are thrown eventually.

Please help me find this problem! This has been going on for much too long already (3-4 months), and I really need to put this problem behind me!