tucsonford

no matter what the outside temp is from 10 to 110 empty or pulling my boat uphill the engine engine temp guage is always mid range and never moves. cold start up in the full cold and moves slowly up to mid range and sits there.

Mulestang

It's not necessarily a directly proportional gauge. From another post:
The cylinder head temperature (CHT) sensor 4.6L, 5.4L:
-is mounted into the wall of the cylinder head and is not connected to any coolant passages.
-sends a signal to the powertrain control module indicating the cylinder head temperature.
i-f the temperature exceeds 126°C (-258°F) 5.4L, 130°C (265°F) 4.6L, the powertrain control module disables four fuel injectors at a time. The powertrain control module will alternate which four injectors are disabled every 32 engine cycles. The four cylinders that are not being fuel injected act as air pumps to aid in cooling the engine.
-if the temperature exceeds 154 °C (310°F) 5.4L, 166°C (330°F) 4.6L, the powertrain control module disables all of the fuel injectors until the engine temperature drops below 153°C (308°F) 4.6L, 154°C (310°F) 5.4L.
DTCs are set.
-If the engine reaches critical temperature, the following happens:
The coolant temperature gauge pointer will read fully hot at 121°C (250°F).
The check gauge warning indicator will illuminate.

tucsonford

Thanks for the quick reply.

velvet fog

That's the way a thermostat is supposed to work. If your cooling system is functioning properly, the engine temp will rise to the degree rating of the thermostat and stay there regardless of load or weather.

If it doesn't, then something is wrong, like a stuck thermostat, clogged radiator, etc.