In the 2.6 beta the coolant and air temp scaling is just "x" for degrees C but I think there must be a calculation going on since the raw value doesn't match.

Has anyone found any linear temperatures to log (eg x-40)? The ECU calculates them internally, might be best to bring them out to request IDs if they aren't already?

I had lookup tables for coolant and air temp in my live mapping app, but I got rid of it when I thought the Evoscan logged items were just a simple linear calculation. Might need to put it back in.

 

RAW Coolant temp ADC = MUT_07
Scaled Coolant temp = MUT_10 (x-40)°C
RAW Intake air temp ADC = MUT_3A
Scaled Intake air temp = MUT_11 (x-40)°C

 

Thanks!

 

Bump

Using 96531706 with GM IAT wired into the fuel temp input I get the following from a data log this morning, after the car sat over night. Local temperature is 33F.

Coolant Temperature
MUT07 reads 37.4 degrees (1.8*x+32)

Coolant Temp Scaled
MUT10 reads 35.6 degrees (1.8*x-40)

Air Temperature
MUT3A reads 15.8 degrees (1.8*x+32)

Manifold Air Temperature
MUT11 reads 33.8 degrees (1.8*x-40)

If scaled coolant temp is derived from the raw coolant temp, shouldn't they match? What is the ECU actually doing to the scaled channels?

I noticed when I disconnected the sensors, considerably different things happened too.

Raw coolant dropped to -74.2F and went right back to original value when the sensor was reconnected

Scaled coolant temp went UP to 177.8 (81C) and then stayed there even after reconnecting the sensor.

Raw Air temp dropped to -85F then went back to original value after reconnecting

Scaled air temp went UP to 77F (25C) and then dropped back to original when reconnected.

I assume the "scaled" temperatures are the actual temperatures used in all the idle, fuel, load, spark, etc. calculations?

 

Raw is actually voltage/resistance of a sensor, the value vs. temperature is not linear so there has to be some linearization done, outcome of that is what I call "scaled".
Yes, you are correct ïn assumption that scaled values are taken in further calculations.

 

Ok, so would it be a good or a bad idea to use MUT 07 and MUT 3A for potentially logging other parameters?

 

It depends on what you are trying to investigate.

If you are changing sensors and trying to get transform/linearization function corrected then it would be a good idea, otherwise I would stick with scaled values.

 

Oh, I just meant changing the channels to log something like a ram address for logging acceleration enrichment parameters or additional items, like how Tephra has used 41 for 1Byte load.

 

Oh, I maybe misunderstood the question :P
Yes they are kind of duplicate values, raw values serve the purpose in my previous post and changing any of MUT value has no effect on calculation, these are there for logging purposes only.