2005 E46 325ci
I actually had about 50psi at the fuel rail when checking it while turning the key but I was suspecting it had to be them as I had ruled most other things out and the puff of blue smoke had to either be oil or fuel but since I wasn't losing oil pretty much at all I thought it had to be one of the injectors malfunctioning and sometimes dumping too much gas into one cylinder when I request a high load.This actually makes sense. I too am chasing an injector issue. Zero PSI at the fuel rail in the mornings before I start the car. Already changed pump/filter checked fuses etc - all OK. I previously noted that the fuel trims are different between the banks. I am thinking that fuel delivery is not consistent across the banks probably because at least 1 injector is leaking/faulty or O-rings. Too cold to do accurate fault-finding and with 140K miles - ordered 6 new VDO injectors. If you order from stealer - twice the price for exact same item. Also read somewhere there were problems with 'early' injectors and Realoem for my car shows they were updated from 2004 onwards. Can't help but feel that fuel trim problems may be due to 'failing' injectors with inconsistent delivery. They tend to be overlooked - not least because they are difficult to fault find and 'prove' a particular injector - and of course expensive.
Based on looking at the plugs after a drive where I saw the smoke I noticed that cylinder 4 and 5 were the only ones a little fouled up so I decided to replace those injectors just now but after putting everything back together I had a bad misfire on cyl 5.
I moved that new injector to cyl 3 and everything ran smooth so I might have just not installed them correctly the first time but I notice now that although I don't have codes I have fairly high negative fuel trims.