Why does AutoTap show less timing advance than commanded without any knock retard?
Here is what the documentation says. Each point links to its source; tables and names vary by computer, operating system and tuning software.
- LS Gen III/IV; 1997-2013: LS ECMs carry two spark tables, High Octane and Low Octane, and the ECM continuously blends its commanded spark timing between them based on how much spark knock it detects. (LSX Magazine)
More in tuning fundamentals, or build a checklist for your swap with the tune checklist tool.
Confidence: medium — sources disagree or are limited; check the sources below.
Community discussion
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Sources
- LS Tuning For Optimum Performance — LSX Magazine