check if you are gettin acual spark...the way I do it (which is prolly an old guy way and everyone here prolly does it different) is take a spark plug hose out of the head; take a screwdriver(with a plastic handle) and stick it in the hose so the tip of the screwdriver is touching the metal ring in the tube; now hold the hose over something metal in your car...(the ground on your head will be fine) and have someone try and start the car..(hold the rubber hose so you dont get shocked!)..now if you see spark then viola you are gettin spark...this is how I check you should try it so you can determine whats wrong...if your ecu isn't trowin any codes and your check engine light isn't on...I don't see what a diagonstic test would do for you..since you car isn't saying nothings wrong...well thats just my .02