By now you may have a blown head gasket or cracked head.
Before you go there, you need to check a few things.
Look for milky oil or water water under your oil fill cap. Also is there any oil in the radiator?
Do you feel any hot air blowing from the fan or does the top hose feel cool when it should be hot. You may have a bad thermostat.
I would remove the thermostat and run it without to see if there is any change. If it runs cool and don't burp coolant, you will need to replace it with a new one. The EFI will need the proper temp range to work properly.
If it is building pressure when it is cold you have a blown head gasket.
Check these and let us know what you find.
