I finished the car litter quest, and I was told my suits were upgraded. However, my radiation protection is only at 4, and trying to go north just results in my death.

Has anyone else experienced this?

make sure to finish any needed quests, like witthier, Also check the character panel for the suit strength and try various ways to change /equip others. I've heard of people having this problem before but it's usually because they didn't finish the needed quests like doing witthier, checking their radiation slot inventory correctly (because it's different than your normal equipment, etc)