This Astra race car came to us with a misfire that only occurs after half an hour or so of running on the race track. We did a few checks and  a bit of digging around. The ECU is a Canems which we use quite a lot of. After running a little data logging and looking at the program it showed the injectors were running beyond their duty cycle and some temperature corrections seemed a little odd. We changed the whole throttle body assembly for one with bigger injectors and the car was remapped to suit. So far it looks as though the problem is solved.