What the table shows
Knock control reacts to knock by retarding timing in the moment. The long term trim goes a step further: it records the retard that past knock events have needed, so the ECU starts with less timing in those areas next time. The bank long term trim table is that record, cell by cell.
Read it as a to-do list. Cells showing trim are where the engine has been knocking, or where the knock system believes it has.
Your two options
On the Knock - Long Term Trim page you can:
- Reset the table, clearing all learned trim.
- Apply to Base Table, which moves the learned corrections into the Ignition Tuning - Base table permanently.
How we use it
- Check the trim first. Is it real knock or noise? Confirm your knock threshold is set properly before trusting it.
- If it's real, look for a cause: fuel quality, intake temperature, a lean cell.
- Only apply to base once you're sure the timing really should come out. Then reset, so the table starts learning from the corrected map.
Don't apply blindly
Applying trims caused by false knock just throws away timing and power. If you're unsure, ask us to look at your logs.
