octane tables

[Camdup Racing]

how do the high and low octane tables work? specifically, how and when does the ecm choose which table to choose from at what given time? can this be manipulated for our benefit? if so, how? or should both tables match each other and forget about it? thanks

[richard head]

how do the high and low octane tables work? specifically, how and when does the ecm choose which table to choose from at what given time? can this be manipulated for our benefit? if so, how? or should both tables match each other and forget about it? thanks

Though they are called high and low octane, I don't think that's actually their function. Basically, in the event of Maf failure the low octane table is used. You're only going to use it when SD tuning. Same with the ve tables.

[Ben Charles]

My understanding it that LOW octane tables are only used if spark knock occurs, low octane fuel is used (87 or 89?) or if some bad gas is accidently used.

[Chevy406]

Make some WOT scans of ignition timing and come back and report if the ECM uses your high octane values or your low octane values.