The warm up valve is controled by engine oil temp and intake air temp. If ecu see's those sensor below a set value it closes the valve. When the temp on the oil gets to its set temp the ecu changes the warm up valve on time. There has been problems with this warm up valve not working when it gets cold. When the tempeture is above the freezing mark the valve does not close. Then when it does trun cold it closes and will not open untell the intake air temp is above 35 derg. The fix is a new turbo base that is where the valves control actuator and sensor is.