IAT Table

[bigtoyz]

Does anyone have sensor table for GM IAT and CLT sensors for data logging? Thought I had it figured off but finding it is off. And are you just making a connection into the out side of the sensors that has the resistance? I soldered into the output side and shrink wrapped it.

[Injuneer]

The GM coolant temp sensors have the same calibration. Shoebox has a table of resistance vs. temperature, which allows you to test the sensor:

http://shbox.com/1/4th_gen_tech2.html#ect

After looking at the table, scroll down for additional info on testing. You need to have 5.0V on the 2-wire connector (connector off the sensor) for the IAT and the CLT sensor in the water pump, with the key on. The CLT sensor in the head is 1-wire, and you should have 12V on that circuit measured from the single wire in the connector to the block, connector off the sensor.

Your data logger should be able to record the indicated temperature in degrees F or degrees C. Most scanners will log both the circuit voltage and the temperature.

[bigtoyz]

Thanks forgot to check his site on that.

[bigtoyz]

Guess I have seen that table once I seen it. Don't I need to know the volts though? Or do the data loggers read the ohm resistance on that instead?

[Injuneer]

The PCM supplies 5V reference across the two pins at the temp sensor connector. The resistance of the sensor will result in a mathematically derived (reduced) voltage on the circuit. This is the voltage the PCM "sees". It translates that voltage into degrees. A data logger should report both the voltage and degrees that it determines from that voltage. Cold temperature = high resistance = high voltage; hot temperature = low resistance = voltage.

In some location in the PCM, there may be a table that translates the voltage into degrees, but this is a standard "GM" calibration, and isn't something that you would change, unless you went into the PCM and changed the bias resistor in the 5V reference supply.

This instruction sheet from the Megasquirt manual may provide you with additional info. Why exactly would you want to change the calibration?

http://msextra.com/doc/ms3/firststart.html

[bigtoyz]

Im not wanting to change anything.....need to know the table so that I can set it up for my LM1 data logger for a Kpa vs CLT with the A/F ratio being graphed from the X and Y axis

[bigtoyz]

Got it figured out finally thank you very much..... Once I got into create a custom table it was giving me what I needed and your info from mega squirt was what I needed. Cant wait to see it finally be correct.