In the I interests of keeping this resource as useful as it has been to me I thought I'd update progress on a starting issue I had on my 56 plate 2.0 tdi 170 bmn engine code.

Problem first started after leaving car in Luton airport for a week when returned had to crank it until nearly flattened batt to start, when I eventually coughed into life (via an oil pump warning) all was fine. First stop was new batt and glow plugs, nothing to report on these really straight forward swap.

Needless to say these made no difference! Using the car daily fault finding was a *****, I'd settled on a fuel draining issue but never had car stood long enough to monitor. Fitted a none return between fuel filter and tandem, also no effect.
Upon inspection fuel filter was massively polluted with oil, problem you've got here is an injector seal and shaft seal for tandem pump give same symptoms! After much deliberation I plumped got the tandem, £205 from. Belfast Audi via eBay was the cheapest, figure that out?! Again this job is a doddle three bolts for the pump just be sure not to snap the vac pipe and to clean the mating face with the head well to get a nice seal on gasket. While in the area I decided to adjust to injector rockers after reading up on here, there's a great guide to follow it worked a treat and proved Audi hadn't bothered on the recall as they were far out enough to effect the idle!

i know that's long winded.... But I'm glad to say problem now sorted! The exact problem I had was an extended crank time dependant on hours left stood, it was tandem pump, the end!