Ignition coil dwell refers to the amount of time (in milliseconds) that current is applied to the coil before it is discharged to fire the spark plug. Proper dwell time is critical for:
When the ignition coil is energized, current begins flowing through its windings. As the current builds, it stores energy in the form of a magnetic field. When the dwell time ends, the coil is rapidly de-energized, collapsing the magnetic field and sending a high-voltage pulse to fire the spark plug.
Too little dwell → weak spark, misfires under load or high RPM
Too much dwell → overheating, coil damage, shortened lifespan, or even ECU driver failure
Voltage: Real-time battery voltage reading (e.g., 13.915 V).
Dwell Time: Current interpolated dwell time being used (e.g., 2.001 ms).
ROM Controls:
Load: Loads a saved dwell table from ECU memory.
Store: Saves current dwell settings to flash.
Import Table: Load dwell tables from other projects or preconfigured profiles.
Quick Cal.: Apply pre-configured values for know ignition coils or use the interface to quickly generate a dwell table from at least two known dwell and volage values.
% Correction Panel:
Apply a uniform adjustment to the currently selected table:
-5%, -1%, +1%, +5%
Custom: Enter a specific value (e.g., -2.5%) for fine-tuning all table entries at once.
Start with known values
Use manufacturer datasheets as a baseline (e.g., 2.0 ms at 14V is common for smart coils).
Test under load
Ensure that the spark is strong enough at high RPM and full load. Misfires may indicate dwell is too low.
Monitor coil temperature
If coils get hot to the touch quickly or drivers get unusually warm, reduce dwell at mid to high voltages.
Cranking vs. running
Increase dwell at low voltages (9–11V) to improve cold start performance. This ensures the coil still builds sufficient energy during engine cranking.
Avoid going over 3.5 ms for most coils unless explicitly designed for it.