Accuracy of DS A/F ratio?

[Sleeper]

How accurate are the A/F ratio #'s on DirectScan?
I cannot afford a WB 02 sensor or EGT gauge (yet), and do not want to rely solely on 02#'s for tuning.

Paul

 

[U1ARUNIT]

DS only shows the commanded air/fuel ratio, not what is actually being read.

 

[Sleeper]

Thanks Mark
I guess I will be tuning by knock and using 02's as reference for now

Paul