Ooops sorry I have a 1978 280z EFI. I read in the EFI bible that " the water temp sensor allows the control unit to richen the mixture until the engine arrives at operating temperature. While the engine is warming up, the oil is thicker; there is more resistance, so more fuel is needed. This sensor is just like the sensor which controls the water temp gauge in the dash. That is , it changes as the engine temp changes." (pg 19 EFI bible)