For megasquirt stuff, I measured the resistance curve of that rear temp sensor. Basically, as the resistance goes up (tends toward an open circuit) the colder the ECU will think it is. Typically, most ECUs will add fuel under this circumstance.. Probably over-fueling if you unplug it.
Temperature Ohms
163F 379 ohms
70F 2479 ohms
35F 5355 ohms
Ref: http://www.2rzturbo.net/?p=82
Most ECT's are negative temp co efficiency. Meaning the the temp goes up, the resistance goes down. So if you were to unplug the sensor the ECM will usually default to -40f. If it is cold outside it will usually start, just run rich. As the vehicle gets warm it requires less fuel to start, so after it reaches operating temp, it will usually not start due to a flood condition. After it cools down it will usually start, might just take longer.
