My car was playing up for quite a while, and it was an intermittant problem. When I took it to the nearby specialists to get it looked at they diagnosed no spark when it started playing up in their hands and couldnt find the cause. Eventually it would start again but the mechanic wasnt sure 100% sure he had cured it. Anyway it wasnt fixed. When I got it back to them the next time it refused to start at all and it was found to be the ECU causing the problem.