Corolla will not start after rain

My 2009 Corolla S will not start after rain. It cranks fine, but no start. Research points to a possible cracked dizzy cap letting moisture in and causing spark problems, but this car has a computer controlled spark with no distributor that I can find. Anyone have any ideas what may be causing this? I still need to get to work even on rainy days... I checked fuel pump and pulled one spark plug which seems to be sparking away.
I had the same problem on a '84 Camry and it was a cracked distributor cap, the crack was very fine and must have only let in moisture under higher heat and heavy rain conditions. I put it off and eventually found some moisture inside. I would think given the inexpensive price of a new cap that it would be IMHO worth it to replace it just to eliminate as a possible cause.