If you've taken off the plug wires from the dizzy just make sure they are back on in the proper firing order, I took mine off and screwed it up putting them back on one time. Car wouldn't start.
What model and year of car?? Is the engine out of a matching year or obd?
Oh and make sure that your TPS and I think your MAP are plugged into the right sensor as well as your IACV and other sensors, they sometimes have the same plugs and can get mixed up if you didn't mark them when removing them from the old engine.
the leads are put back in the correct order
1-3-4-2
The car is a EK3 (uk) 1997 and the engine is from a MB6 (uk same engine as b18c1)
and i have checked all the connectors and they are all correct
cheers for your help though !