Hondata

I am trying to resolve what seems to be a disagreement in ignition parameters. Attached is my calibration and datalog. At timestamp 15:00, the log shows the following (while idling) - RPM: 1000, IGN = 5, Knock Retard = 0, Limit = 19, K Control = 55% and MAP =29kPA.

My calibration tables show the following: Ignition Low = 12, Knock limit low = 12, knock retard low = 9.7

Based on the formula in Flashpro help for calculating ignition advance:

Ignition advance = minimum(MBT Ignition, MBT Ignition + knock ignition limit - (knock retard x knock control))


From datalog, I get min(12, 12+19-(0X.55)) = 12 degrees
From tables, I get min(12, 12+12-(9.7X.55)) = 12 degrees

This generates several questions:

1. Why the big difference between IGN in datalog (5 degrees) and calculated value from table or datalog (12)?
2. Why the big difference between Limit in datalog (19 degrees) and knock limit low in table (12)?
3. Why the big difference between Knock retard in datalog (0 degrees) and knock retard in table (9.7)?
4. Is Ignition advance calculated from the equation above the same as IGN in the datalog?

I ask these questions because I'm trying to alter my ignition tables to eliminate knocks occurring in the 2000-2400 range at about 84kPA as shown in the log. Before I proceed, I want to resolve these apparent discrepancies above.

Thanks, Mike

are you referring to ignition when idling?

In this specific case, yes. But I have noticed these discrepancies at other throttle positions.

Also, does knock retard on the log only refer to ignition retard related to knock sensitivity, the knock retard table or a sum of both?

These vehicles have ignition controlled idle so you will see the idle fluctuate a lot when idling.

Knock retard is the amount of timing it is regarding due to knock control.

Okay, thank you. One other question. If a knock situation happens when the ignition timing is being determined by:

MBT Ignition + knock ignition limit - (knock retard x knock control) becuase it is less than MBT Ignition, does it make sense to lower the knock ignition limit table in the area of knock instead of lowering the ignition table.