hundail elantra,,,im lost ,,but not the first time on 2003 Hyundai Elantra

intermittent wont start ,,,has no check engine light when this occurs ,,,have replaced used ecm and new ignition switch in collumb

Asked by for the 2003 Hyundai Elantra
I would suspect either your cam shaft sensor or your crank shaft sensor, they both can do this on this engine. The symptom will be a long crank time before starting or the car will just crank and crank and not ever start. Also, in some cases these sensor can set codes, but will NOT illuminate the check engine light.
the check engine light will not come on in the dash when the key is in the on position,,,that is when the car wont start ,,,when the ck engine light is on the vehicle starts fine,,