When is the low octane table referenced - E38?

[Michael_D]

I have been logging both of my vehicles with the E38. I've seen as much as 10 deg KR, but the logs show the main table being referenced (I am logging spark state). Fuel in my area sucks, 90 octane and it's crap, so I expect to see some KR, but now that I am not seeing the low octane table being referenced under these KR conditions, I'm just wondering when, or if the low octane tables are ever referenced.

[Shrek]

... I have been logging both of my vehicles with the E38 ... I'm just wondering when, or if the low octane tables are ever referenced ...

E38 / E67 use a percent spark bias approach. With quality fuel you may see 100% High octane spark, and obviously 0% Low octane spark table.

A good tune will run very close to this.

If you are overly aggressive with the High octane spark values, you may see a bias begin to occur - 90% High octane table and 10% Low octane table, etc.

E38 / E67 don't simply run off the High or Low octane spark tables - they continuously blend these values for the best spark per given situation.

[Michael_D]

Thank you! My tables are pretty pathetic actually. Lower than the stock low octane table in many areas. I've been pulling timing out of the low rpm / low lode areas the most, as when in 5th or 6th gear, light acceleration seams to be the most problematic areas.

[Chris@HPTuners]

the ECM interpolates between the high octane and low octane all the time based on the Knock Learn Factor. You can log this in the scanner.

Chris...

[NICKY BOY]

Very intresting

[Michael_D]

the ECM interpolates between the high octane and low octane all the time based on the Knock Learn Factor. You can log this in the scanner.

Chris...

Which PID would I log Chris?

[Iam Broke]

Knock Learn Factor is in the PID list under Engine -> Retard.