Just out of interest. I finally had my car checked with a tuner's diagnostics machine which apparently pics up quite a bit more information than the standard diagnostics machines at most agents, and they took the car for a drive while the diagnostics was being read, so basically a live read of what was all going on. This is what they found.
Engine is not pinking, the DISA flaps are fluttering and making constant corrections but incorrectly which is causing the pinking type noise and causing the engine to run less smoothly overall. Then more worryingly, the thermostat is not working properly and forcing the engine to run too cool, so there is some over-fuelling going on, especially on colder days. The Valvetronic motor is apparently 10% out of spec, not too sure what that means, but apparently can be sorted out with software, also not sure - ECU flash?! Cylinders 1 and 5 have some strange injector / valve behaviour, so either those injectors aren't working properly or the valves are not seating correctly - but this will need further investigation.
The first thing that needs to be done is to replace the two DISA flaps and the thermostat - then run tests again to see if this solves the problems.
At least now I know I am not imagining things!
BMW E90 330i (M) '05 (His) | (Hers) BMW E46 320i f/l (M) '03