R33 Fuel Level Help NGTR+ MXP

[klutched]

Hey guys, 

Sorry if this isnt the right section.

Running a G4+ NGTR in my 33 with a Link MXP strada. Currently have the fuel level hooked up via my MXP through a haltech fuel level conditioner. I went through and added 2L increments of fuel and took the mV readings from the aim live values and punched them all into the table to set up fuel level. 

I got to 34L and it read 30mV, and then put another 2L in and went to -40mV.... so obviously in the aim software you cant put negative values in so i only got to 34L. Ive currently got it showing Liters used from full and on a full tank its showing -15L and as I use more fuel it goes positive. 

Anyone know why i would be getting negative values? 

Thanks

Liters mV

0 1635mv
4 1660mv
6 1450mv
8 1390
10 1245
12 1100
14 1015
16 900
18 845
20 700
22 625
24 550
26 465
28 300
30 200
32 135
34 30
36 -40
38 -110
40 -185
41.5 -245

values for reference

[Adamw]

You dont even need the conditioner, you can connect the sensor direct to the dash, you do need to wire in a a pull-up resistor though.  

I suspect there is a conflict between the haltech device and the dash ground or something.  

https://www.aim-sportline.com/download/faqs/eng/hardware/sensors/FAQ_Sensors_Fuel_level_100_eng.pdf