Really the next time it fails to burst into life....then do the checks of voltage at 5th injector.....also remove injector...place in suitable container....crank engine check good spray of fuel...be safe hear as injector on main pressure line...as ive said also check the injector plug is clean and the Terminals are a good fit on the injector....as well as the Timer itself...these plugs do give intermitant conections. Peter