Liquid Temp Resource Page
There are multiple types of different liquids in an engine and vehicle, your ECU relies on having accurate data from the coolant temp sensor in order to get good drivability. You may be interested in data logging fluid temp through out a race, or even just to determine if that cooling upgrade was effective.
This will depend on what you are measuring. Usually you want to know the hottest temperature something is as that's your limiting factor. For coolant temp this is where the water exits the head and goes into the radiator. For oil its as close to the bearings as possible, either in the pan or an oil gallery feeding them. Its important to pick a place that has good flow and will be reflective of the area you want to measure if the sensor can't be directly in that area.
NTC temperature sensors are 2 wire, a signal and sensor ground. Polarity doesn't matter, either pin can be signal or sensor ground. Best practice to make them the same amoung all your 2 wire sensors.
The sensor changes its resistance value as the temperature changes. Most NTC sensors are negative coefficient, meaning the hotter they get the less resistance they are.
All our kits come with 3 different resistors, shown below. Most ECU's will have a built in pull up resistor on one or two inputs specifically for the IAT sensor but in the event you are adding a sensor to measure air temp for datalogging purposes and the input does not have on the resistors will be necessary to wired in externally. Choose resistor value based on what temperatures you care most about. For example, we recommend a 560 ohm for Oil temp because it gives more resolution when the oil is hot vs when its cold.
One side of the resistor is connected to 5V, the other to the sensor signal wire.
560 Ohm Resistor
1000 ohm resistor
2000 ohm resistor
2200 ohm resistor
Calibration - Linked below are screenshots and table calibrations for various common aftermarket ECU's. We have noted the common pull up value that the table is designed to work with. Using a different value resistor will result in an incorrect value in the ECU.
Here is a table showing the temp sender's resistance vs the voltage value for each pull up resistor value. If there is not a file available for your brand of ECU the table can be populated manually from the information on this table. Note all pull up resistors are to the 5V supply.
ECUmaster - typical pull up 2200 Ohm
Haltech - Typical pull up 1000 ohm
Link - Typical pull up 1000 ohm
Link G4 calibration
Holley - no pull up options, must use external. Table show is for 2k pull up
Holley Must entered manually, temperature in Fahrenheit.