Hi guys

Last months I rebuild one of my sapphs and now when the car starts first time I found one problem

The first cilinder (the one near the timing belt) fails but the injector is running ok and the spark plug is ok too. I'll try with the ecu of my other sapph and the problem is the same

What can be the problem? what sensors uses the first cilinder?

Regards

EDIT: Comprenssion is ok too in all the cilinders