IAT Sensor Scaling Calibration

[kidturbo]

Hey guys working on a LLY mod to relocate the IAT sensor from the MAF to the boost side of the intake so it will actually measure some useful data like later models LBZ and up. Have found that most performance tuners are using the GM Camaro IAT sensor because it is fast response and cost like $20. However the Ohms of resistance are slightly different from the stock LLY MAF unit. So will need to recalibrate the A/D conversion scaling tables B0204 and B0205.

Problem is, there is no rhyme or reason with these two tables.

B0204
The ECM samples the intake air temp sensor voltage to determine the intake air temp using an analogue to digital (A/D) converter.
This table defines the sensor voltage measured by the ECM and what that value corresponds to as an actual intake air temperature from the sensor.
The ECM uses two tables for more accuracy, this table is used when the air temp is hot.

Could someone please explain how these tables actually work, and how to recalibrate these accurately? The values 0-1024 are not Ohms or Volts, so what are they? I notice all the temp sensors on the LLY use that same scale.

I have the Ohms chart for the LLY MAF mounted IAT and the new screw in IAT. Will probably use a potentiometer to scale out the new resistance values, but with two tables, how do you know which one the ECM is using at which moment? And Why...

Thanks

-K

[kidturbo]

Nobody ???

[kidturbo]

Ok from what I've found, looks like E60's temps sensor circuits use a 348 / 4K(combined) ohm resistor set for the Bias.

If anyone can verify that, I've found a tool to map out the resistance values with temp to resistance chart.

[kidturbo]

16945

Here ya go. Sensor scaling in 10bit ADC, converted to ohms resistance, for both Scaling 1 and Scaling 2 tables used [by at least] the LLY for all temperature sensor.

Feel free to verify it.
I've tested it by re-mapping the IAT sensor scaling values on my LLY to work with a ACR-12V-3 GM#5744430 sensor in the Y-Pipe. Works great...

Cheers,

-K