Permanent Spark Override Reset

Ignition Schematic:

Ignition Synchronization:

Ignition timing on the 4.6L Northstar is not adjustable for tune up or emission readings


The base ignition timing on the 4.6L Northstar is determined by the relationship of the crankshaft position sensors to the reluctor ring. This relationship is not adjustable and results in a base ignition timing of 10° BTDC.

The PCM incorporates a permanent spark control override, PS22 (SERVICE SPK), which allows base ignition timing to be lowered electronically if spark knock (detonation) is encountered during normal operation due to the use of low octane fuel. Base ignition timing can be temporarily lowered for testing using this override down to 60° BTDC. This override is stored in PCM memory and will remain at the set timing unless the battery is disconnected.

To reset permanent spark override:
1. Key "ON", enter diagnostics.
2. Select PCM override PS22 (SERVICE SPK).
3. Press "COOLER" button to lower ignition base timing and press "WARMER" button to increase ignition base timing.