SD card data acquisition

I actual ended up using a formula to find the slop.

float psi = (0.16532258 * sensorVoltage) - 2.2125;

The above worked perfectly. I also checked my ground per your recommendations. The problem I'm facing now is my other sensor, Anfield T201-015P-G-6-M12-4-N-T1. The output voltage is 1-5V with supply voltage of 8 -30v. I am using a power supply to provide the 8v to the sensor.

The code im using:

 float psi = (0.183284457 * rawAnalogData) - 37.5;

is based on the same principles as the other code above. The readings seem to be off by 10 psi when you are at 100psi.

I am powering the Arduino through the 9v jack and the USB port, connection through USB is being used to be able to view the Serial monitor. Please see the attached image.