Engine won't start.....
 

Sorry to be so vague with the title, just asking for any ideas what so ever that might help out.

so a year ago I had a Alcatek ecu you a 2.1 engine which melted 2 pistons, this year have had the engine built again but gonna run syvecs this time so had the sensor kit fitted ready, cut a long story short I have fitted the engine in and and fitted my old standard ecu that was mapped before I went alcatek and it wouldn't start due to losing the sigma fob so I've had all that removed and had a new toad alarm and that fitted.

guess what still won't start....... I seem to have fuel as I have a pressure reg fitted and have it set a 3 bar whilst it's cranking over, checked all spark plugs and they seem to be firing and I've got air, so on paper it should start but won't.

could this be down to the key losin it's code? Have I missed something that is staring me in the face? Should I just put the syvecs on and surely a mapper can put a map on it and see from a laptop what is going wrong?

any help would be appreciated