With increasing MAT, ignition retard is desirable to avoid detonation. Unfortunately it takes extreme effort to finetune ignition for a wide range of manifold temps, you need
- a climate chamber (5M EUR)
- or half year for this
- though somewhat useful results can be obtained in half day if temp difference is at least 40C
- or you can heat the charge cooler with gas-burner, or change airflow (fan), or swap it or do other tricks to change MAT during a dyno session
Therefore almost noone finetunes for a wide temprange.
If you fine-tune your engine, please share your experience (measurement results) here. Until than, best-breed experience suggests that marginal retard is needed below 40C, and above 50..60C the retard must be considerable.
Since 2006-11-30 1.1.1 and 1.0.65 firmware, these retard curves are wired in:
The same in Fahrenheit:
That means a few degrees subtracted from the base ignition advance curve. Note that there are other adjustments, like knock-retard, idle-ignadv retard/advance.
If your measurements are different (say, at least +-1 degree change in base timing needed at different temps), we'll make it configurable immediately for you. Until someone uses it, there is no reason to have another config (just another chance to get something wrong).
- The timing displayed in the dashboard and datalogs is the actual timing (you do NOT need to subtract this MAT retard)
See also