Hi all , I am new on this forum so I hope you can help me. I bought a 1991 520i recently but the engine failed when bringing the car back from the UK, its a M20 engine. I found a replacement engine its a m20 but it came out of a 320i touring car. The engine has been fitted but will not start it looks like there is an imobiliser switched on as the fuel pump wont pump and there is no spark, the factory fitted alarm appears to be working fine and activates and deactivates. I have changed the ecu as well . Your help would be appreciated, as this is driving me insane.!!