I blew the engine up in my mk6 at ford fair on track

 

since then I have changed the engine and gone back from a 2.0l to a 1.8 and my car will now not idle and when it does start and you hold it on throttle it has a missfire

 

i have changed the ecu back to the 1.8 ecu, checked the plugs, leads, maf, lambda, checked for any air leaks and all the wires are connected in the right place, I have changed the cam and crank position sensor and it still has the same problem 

 

another issue it has is when the ignition is left on and the engine is cranked with a spanner the fuel pump kicks in for a few seconds like it does when you first turn the ignition on before starting 

 

any help would be appreciated before I lose my rag and want to kick fook out of it 

another issue it has is when the ignition is left on and the engine is cranked with a spanner the fuel pump kicks in for a few seconds like it does when you first turn the ignition on before starting 

 

That's not a fault - it's correct operation. After the initial prime the ECU waits until it starts receiving a signal from the crank sensor before turning the pump back on. i.e. the pump only runs when the engine is turning.