MoTeC Global Forum

I have a Magnetti Marelli fast reacting intake air temp sensor i want to replace the stock, and slow, Nissan Skyline RB26 one with. How do I set the figures for it in the latest software for an M800? I have the spec sheet for it ( http://www.mmcompsys.com/download_zone/ ... web_01.pdf ) Thanks.

You can use a custom calibration in your input setup with the following values:
Temp Volts
-40 4.95
-20 4.91
-10 4.72
0 4.53
10 4.28
20 3.95
30 3.54
40 3.08
50 2.60
60 2.14
70 1.73
80 1.38
90 1.09
100 0.83
110 0.65
120 0.45

Hi,
I am also installing a Marelli sensor. In the M800 spec sheet, I read that the temperature inputs have 1k pullup resistor and a 100k pulldown resistor. Is this correct ?
The values in your post are calculated without the 100k resistor. If it is present, your values make a significant error at low temperature. You read -30° instead of real -40°.

Angelo

-Yes you are correct the pull down will make a difference at the hich resistance end of the scale. The following values are calculated with the pull down as well:

40 4.90
-30 4.86
-20 4.79
-10 4.72
0 4.49
10 4.25
20 3.92
25 3.72
30 3.51
40 3.06
50 2.58
60 2.13
70 1.73
80 1.37
90 1.09
100 0.83
110 0.65
125 0.45

Ross,

Could you please explain how these values are calculated?

I have a different sensor I need the values for in M800.

Regards

I posted values in your post.
This is basic electronics.
You have your sensor, Rs, connected in parallel with the pull-down 100k, Rd. We can obtain an equivalent resistor Re, with the formula Re= (Rd x Rs) / (Rd + Rs)

Then this resistor is connected to a pull-up resistor, Ru, to 5 volts. This is a voltage divider, and the voltage could be calculated as Vs = 5 x (Re / ( Re + Ru)).

Enter this in excel and you obtain the values in the previous posts.

Angelo

Just what I was looking for.

Thank you very much.

Chris Wilson wrote:I have a Magnetti Marelli fast reacting intake air temp sensor

Are we talking about the ATS04 Marelli?
Thanks

Yes this calibration is for Marelli ATS04 sensor.

Rude Engineering wrote:Yes this calibration is for Marelli ATS04 sensor.

Thanks