What is the difference between BLM fine and BLM main, and which should I use for VE tuning?

 

The short answer: For VE tuning, use BLM (Main) as shown in the v5 ADX file and logs. This is the true BLM.

The long answer: The S_AUJP v5 ADX file item "BLM (Fine)" is incorrectly described. The correct long description should be: "INT-based Closed Loop BPW Correction Factor". The v5 variable reported for BLM (Fine) is L00E8, which is the "INT +/- o2 proportional gain counts for increased BPW correction from the Table at 0x4DE" ('+' if FAST o2 voltage is going-Lean; '-' if going-Rich). In CL, BPW is always corrected based on the INT's deviation from 128. It will be further corrected by the gain counts from the table. If in CL and Idling/Low MPH (for o2 purposes: TPS <= 15% AND MPH <= 15), the counts will range from 1 to 3 (25% of the table values). If other than Idling, counts will range from 4 to 12 (higher counts at higher % adjusted SLOW o2 voltage errors and air flows). If in OL, the INT =128 and the counts will =0 resulting in no BPW correction because there is no deviation from 128.

 

Thanks for the explanation. I was using "fine", and the ve's were going opposite of my WB.