Ignition timing must often be adjusted based on coolant and air temperatures to optimize combustion, improve cold-start behavior, prevent knock, and maintain drivability across varying weather and engine conditions.
The RM-Primis ECU provides two dedicated compensation tables for this purpose:
¶ CLT Comp (Coolant Temperature Ignition Compensation)
Purpose: Adjusts ignition timing based on engine coolant temperature.
When the engine is cold, combustion efficiency is poor, and advancing timing helps burn fuel more completely. This table allows ignition advance when cold, and removes the compensation once the engine reaches normal operating temperature.
Coolant Temp (°C)
Ignition Advance (°)
105.0
0.0
60.0
0.0
20.0
1.0
0.0
2.6
-20.0
4.2
-40.0
6.0
Typical Use:
Cold engines: Advance ignition up to 3–6° for smoother idle and better cold-start combustion.
Warm engines: Set to 0.0° to avoid unnecessary timing changes.
Actual Value Display:
Temperature: Live coolant temperature reading (e.g., 61.6 °C).
Compensation: Shows real-time interpolated ignition offset being applied.
Disable: Checkbox to turn off this compensation entirely during tuning.
ROM Controls:
Load: Retrieve a saved compensation table.
Store: Save current values to flash memory.
Import Table: Bring in settings from another tune or base map.
¶ IAT Comp (Intake Air Temperature Ignition Compensation)
Purpose: Adjusts ignition timing based on intake air temperature.
Air temperature has a direct impact on knock resistance—hotter air = higher knock risk, requiring retardation of timing. Conversely, cooler air is denser and more knock-resistant, allowing more timing advance.
Air Temp (°C)
Ignition Offset (°)
100.0
-6.0
80.0
-2.0
40.0 to 0.0
0.0
-20.0
0.2
-40.0
2.0
Typical Use:
Retard timing in hot conditions (e.g., +60°C intake air temp) to reduce knock risk.
Slightly advance in cold conditions to maximize efficiency and throttle response.
Actual Value Display:
Temperature: Real-time intake air temperature (e.g., 38.4 °C).
Compensation: Displays the current ignition correction being applied.
Disable: Prevents this table from affecting ignition timing—use for troubleshooting or testing.
ROM Controls:
Same as CLT—load, store, or import predefined compensation tables.