AFR reading variation

[Jo LeForce]

Using an Innovate LM-1 to read AFR I had selected the innovate LC-1 calibration & had programed the LM-1 both output signals to emulate the LC-1s (0V = 0.5 lambda & 5V = 1.523 lambda). Connected the reader to AN-Volt4 via a 3-wire AUX cable, the tip is signal & the bottom is grounded to sensor ground on the ECU. As I use different AUX cables, sometimes AFR readings are spot on, showing identical readings on both the LM-1 screen & PCLink, but often there is a difference in readings with PClink showing leaner AFR value than the reader by 1-1.5 AFR! What could be causing such variation in AFR readings?

[Hellafabrication]

Sounds like a ground loop issue if its not consistent.

[Adamw]

If you are saying you get a different reading when you use a different cable then the suggestion would be there is a bad connection/high resistance in one/some of those cables.

To troubleshoot I would set up the LM1 to output a flatline voltage, i.e. 0.5Lambda=2.5V, 1.5Lambda=2.5V, then it will output 2.5V all the time.  You can also set up the link analog input to display voltage.  If PCLink doesnot show 2.5V then you can get a multimeter and check there is 2.5V at every connection point.