Ignition control

Spark is a 3D table (RPM × load) plus dwell, plus knock retard, plus CLT/IAT trims. The table is commanded BTDC at the crank. If trigger offset is wrong, the whole table is shifted — do not “tune around” a 12° offset error.

Dwell

Dwell vs battery voltage. Smart coils have a recommended range; exceeding it cooks the coil, starving it blows the spark out under boost. Start with the coil maker’s numbers. Watch coil temperature after a session.

Building the table

• Cranking: 8–12° on most engines. More is not kinder; it is harder on the starter and on flooded engines.
• Idle: 12–18° typical. Too much idle advance makes a lumpy, stall-prone idle on a big cam.
• Cruise: this is where MBT lives on a petrol NA engine — often 30–40°. Listen and look at EGTs, not just a knock sensor.
• Boost: timing comes out as MAP goes up. How much is fuel, compression, chamber and inlet temp. Knock control is the backstop, not the map.

Coil assignment

Outputs are Ignition 1–12. You map them to cylinders in the firing-order / cylinder-assignment menu. Wiring cylinder 1’s coil to Ignition 1 is a convention, not a requirement — but breaking the convention without a note on the bulkhead will cost you a Saturday.