What does spark retard mean in the tune, and which tables control it?
Spark retard means the computer is taking timing out — most often because it detected knock.
How LS computers handle it (LSX Magazine):
- Spark tables mainly exist to prevent detonation. The menus include base spark, high-octane and low-octane spark tables, and corrections for intake air temperature and coolant temperature.
- High vs low octane: the computer continuously blends between the high-octane and low-octane tables based on how much knock it detects. On 87 octane, timing drifts toward the low-octane table; premium lets it favor the high-octane table.
- Size of the difference: the two tables typically differ by 6–15 degrees at high rpm and high load.
If you see retard in your logs, find out whether it's knock-driven or a temperature correction before changing tables. See tuning fundamentals.
Want to do it yourself? See who tunes it, and how to learn.
Confidence: medium — sources disagree or are limited; check the sources below.
Community discussion
Related questions
- Why would VATS and starter checks refuse to disable on an E38 ECM even after a Write Entire?
- What is the exact procedure to disable DoD/AFM in the tune without a mechanical delete kit?
- How do I set up 6L80E part-throttle and WOT shift tables after a gear and tire change in an engine swap?
- How do I add a real flex fuel sensor to an E38 Camaro and dial in E85 — what needs adjusting beyond enabling multifuel?
- What is needed to segment-swap a 4L60e E38/T42 truck to a 4L80E?
- Does simply selecting 4L80E under the transmission tab convert a 4L60E tune, or is a segment swap required?
Sources
- Late-Model Tuning 101 With EFILive — LSX Magazine
- LS Tuning For Optimum Performance — LSX Magazine