Hey guys, this is my first post here. I'm having two pretty major problems with my 280z. The first is that my Z cannot start and stay started on a cold engine without assistance(from the gas pedal). If I don't apply the gas it will eventually kill itself. Naturally my first thought was "Must be the cold start system". So I replaced the cold start valve, thermotime sensor, and water temp sensor. But alas, it was to no avail. My second problem is that when turning my car OFF after driving it, and then restarting it, the Z starts to overheat and has some real problems idling without first letting the engine cool. I have to apply the gas pedal to get the engine to cool itself, otherwise it will die. And even then it takes a long time of feathering the gas! When it comes to this second problem I just have no idea where to start. My Z is clearly lazy and just hates to run. Any ideas?

Also, parts that I have replaced recently:
-Thermotime
-Cold start valve
-Water temp sensor
-Air regulator
-All the wiring and connector involved with these parts

Thanks!

 

Welcome to ZDriver!

Check the AIR REGULATOR. It's the other cold start idle component.

As for the overheating... is there enough coolant in the radiator? Have you checked the actual temp with an infrared thermometer? You should see a ~20*F-30*F drop from the thermostat housing to the bottom radiator hose.