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OBD1 8-Bit Ignition Advance Formula

Ignition timing advance conversion formula for 8-bit OBD1 Honda ECUs.

Beginner

Adapted from pgmfi.org wiki

In 8-bit OBD1 Honda ECUs, the ignition advance value (in degrees) is calculated from the raw table byte value v using the following formula:

Ignition Advance (Degrees) = (v - 24) / 4

Where:

  • v is the decimal representation of the byte at the ignition map cell.

Credits and source

Source Adapted from OBD1 8bit Advance on pgmfi.org wiki. Licensed under CC BY-NC-SA 1.0.