BLS cuts out after a few seconds even after new engine and E

[dixey]

Afternoon all, I'm hoping someone can point me in the right direction as I'm pulling hair out with an audi I've bought of a mate. 2009 1.9tds BLS engine sounded terrible so it was booked into the garage by the previous owners but before the date it was due in it broke down. It would start for a few seconds then cut out. It said low oil level and low coolant level, garage tore into the top end and said it needed a new camshaft as it had been ran dry. I bought said audi for scrap value and replaced the engine with a low mileage one. Thing is the original reason it broke down is still present, it says low oil and low coolant then cuts out but both oil and coolant are full. I got an auto electrician round who plugged it in and after ten minutes said he could not see any problems with it then buggered off £45 richer lol I bought a second hand ECUkey kit (ignition key with barrel ect, speed clocks, ecu bcm and fuse board under the bonnet. Still does exactly the same. I've ran out of ideas 

[dixey]

Yes oil pump is working and there is pressure there, unsure about water pump but I can't imagine the waterpump not spinning would cause these symptoms. Also it's the same problem with 2 completely different engines which would give the impression its nothing to do with the engine. The electrical parts I changed are already all coded together that's why I changed them all together, to remove the need for any coding. Seeing as though it made zero difference, with both ecu sets, that would also indicate to me that its nothing to do with, ecu, bcm, ignition, immobiliser speedo ect. I'm stumped, really don't know what to do