greg turbo

i have bought the engine and loom for an rs turbo to build a zvh for my escort gti the engine is in and starts when it wants but wil not idel but revs very clean when it is running. i have been over all the timinig and done all the normal checks the only thing i have noticed is the spark is not to strong even with the dizzy fully advanced. iam now woundering if it could be the ecu, on the loom i have it has a green plug which usually goes to the in let manifold but mind doesnt have the sensor so iam woundering if the engine is from a s1 or if the earlyer s2 dont have one, there for if it was a s1 does this mean i have to use a s1 ecu or could i use a s2 like i have. another thing is in the past when i have had a s2 when u prime the metering head and then loosen one of the injector unions it squirts fuel out at high pressure this one doesnt and the fuel injection guy says it should only put the cold start under pressure until it fires is this so. any other suggestion of what could be causing a weak spark cheers greg