there will be 12 volts from the coil with the ignition on as its a permanant 12 volt switched feed and the outer 2 wires goto the ECU and switch to earth via the ecu - this creates the spark

check that the crank sensor on the back left of the block next to the flywheel is sound - it picks up signals from a slotted 32 groove disc on the flywheel.

check the wiring loom to the crank sensor as it can deteriate and this will lead to rough running, poor starting and running like a sack of wallnuts when warm


this is all presuming its an RS2000 you are talking about, if not, you could of told us the car instead