AFR, actual vs logged

[Jo LeForce]

There is a significant difference between actual AFR readings vs logged values via an analog input. I'm using an Innovate LM-1 to log AFR, I have programed both analog outputs on the reader to match the values of the LC-1 (0v = 0.500 Lambda / 5v = 1.523 Lambda) so I could pick the LC-1 from the calibration list. I connected the wire to AN Volt-4, grounding it to the ECU. As an example, if the LM-1 screen reads 12 AFR the logged value would be around 14.4 AFR!

Any possible causes to such issue?

Thanks

 

[JMP]

Ground offset. check what voltage the ECU is reading on the analogue input compared to what the LM-1 should have on the output

[Typ17 16vg60]

You can correct it in the offset table

By my it was not so much, driven and compare it, correct it.. 

Some people talk about the groundwire position, is it on the motor or Batterie or inside... 

[Jo LeForce]

I appreciate the useful feedback guys. A couple questions:

Where is the offset table located? Is it the error values under each analog input?

If I set the lambda reader to output 2.50v for voltage testing & if the ECU, as an example sees 3v then how do you suggest I modify the offset based on such theoretical 0.5v difference? 

Would any such voltage difference stay constant throughout the logging range?

[Adamw]

3 hours ago, Jo LeForce said:

I appreciate the useful feedback guys. A couple questions:

Where is the offset table located? Is it the error values under each analog input?

If I set the lambda reader to output 2.50v for voltage testing & if the ECU, as an example sees 3v then how do you suggest I modify the offset based on such theoretical 0.5v difference? 

Would any such voltage difference stay constant throughout the logging range?

To do this you would use a custom calibration rather than the built-in "LC1" calibration.  Usually the offset will be linear so you can set your Lambda analog input to use Cal 4, 5 or 6 then enter the appropriate Lambda Vs Volts into one of those cal tables.