Intake Air temp sensor

[thommo]

Hey guys

I have a question regarding using an air temp sensor with the DLP converter.

From what i have read up on, I have to use a voltage divider with the air temp sensor so Nistune will see the output as 0-5v.
And i need to supply the sensor with 5v instead of 12v with a step down converter.

My question is i would like to use a GM sensor but i don't know how to translate their temp V resistance into an accurate voltage for nistune.
I have attached the GM sensor tech sheet that has the graphs.
Could anyone with experience let me know what values I will need to put in the Nistune lookup table to get accurate readings

Thanks
Scott

[Matt]

I had to google this one for the pull up resistance, which appeared to vary depending on the range you wanted from it
http://www.efi101.com/forum/viewtopic.p ... a9bd7e0a3c

So from this forum 2490 ohms for 0-50C (32F to 122F) for AIT would be suitable

Current depends on the DLP (USB is normally 500mA supply with 5V output)

I=V/R
V = R * I
volt =resistance x 0.5

Table would look something like from the sheet, except halve the values on the right

0 9,256
5 7,153
10 5,572
15 4,373
20 3,457
25 2,752
30 2,205
35 1,778
40 1,443
45 1,177
50 965

I think your CSV file should look like :

Millivolts, Temperature
482 50
588 45
721 40
889 35
1102 30
1376 25
1728 20
2186 15
2786 10
3576 5
4628 0

Power from 5V from DLP (10 bit AD from memory)
Ground other to DLP GND
Pull up other output end to 5V via 2.49K resistor to 5VCC (and also tie that leg to DLP AD input)

[thommo]

Hey Matt

Thanks heaps for looking that up for me.
Ill get it all together and post a photo to make sure i have it all connected right.

Cheers

[nffdasilva]

nice info, thx