To convert raw hexadecimal data from an OBD0 Honda ECU ROM into usable ignition advance values, use the following calculation.

Calculation Formula#

The ignition advance in degrees is derived from the raw byte value stored at the specific ignition map memory address:

Ignition Advance (Degrees) = (Decimal_Value - 15) * 0.36

Variables#

• Decimal_Value: The base-10 integer representation of the hexadecimal byte found at the ignition map offset.

Note

This formula applies specifically to standard OBD0 ROM structures. Ensure your map offsets are correctly identified before applying this conversion.

Tip

When working with hex editors, ensure you convert the hex byte to decimal before subtracting 15 to avoid calculation errors.