Thanks guys sorry for the delay in repling , so after your replies i have had a look at battery voltage on cranking both during a start up and failed start up when the car starts battery voltage on cranking drops to 11.5 volts and starts fine however when failed start battery voltage is dropping to 10.3 volts which my understanding would be too low for ecu to function and possibly slow crank speed although it doesnt sound slow . After speaking to the customer about my concerns about the battery may not be a calcium type which as far as i am aware is needed on smart charge he has informed me the battery is about 12 months old and doesnt think it needs a new battery (his choice not mine) and to be fair it passes a drop test and is fully charged unfortuantly i dont have an electronic smart battery tester , i have then looked at starter cranking amps which peaks at 350 and holds around 280 amps does anyone know if this is excessive as i dont have any known good readings