This screen configures ethanol-based compensations in the RM-Primis ECU for:
Used in conjunction with a flex-fuel ethanol sensor, this system allows seamless transition between gasoline and ethanol blends like E85.
| Advantage | Benefit |
|---|---|
| Higher Octane (~105 RON) | Greater knock resistance — supports more ignition advance |
| Cooling Effect | Ethanol absorbs more heat during vaporization, reducing intake temps |
| More Power Potential | Allows for more boost and spark advance |
| Sustainable Fuel | Ethanol is a renewable fuel (commonly derived from corn/sugarcane) |
| Affordable Race Performance | E85 provides race fuel performance at a fraction of the cost |
❗ Ethanol requires ~30–35% more fuel volume than gasoline due to lower energy content.
The ECU reads ethanol content using a frequency-based digital signal from sensors such as:
Connect Sensor Signal Wire to a digital input such as:
Hall InputCAM 1CAM 2Configure the Input in the ECU's digital input section:
Pull-up Resistor:
📄 Always consult the sensor datasheet or contact RM Racing Electronics customer support for wiring and pull-up requirements specific to your installation.
Three tables define how the ECU adapts behavior based on ethanol %:
| Ethanol % | Fuel Add (%) |
|---|---|
| 0.00 | 0.00 |
| 100.00 | ~63.00 |
| Ethanol % | Ign. Advance (deg) |
|---|---|
| 0.00 | 0.00 |
| 100.00 | 5.00 |
| Ethanol % | Boost Ratio (%) |
|---|---|
| 0.00 | 100.00 |
| 100.00 | 110.00 |
This block automatically adjusts AFR target if using blended fuel and AFR strategies.
Displays live sensor data:
| Feature | Role |
|---|---|
| Fuel Add | Adds more fuel as ethanol % increases |
| Ignition Add | Advances timing to extract power from E85 |
| Boost Ratio | Scales boost safely with fuel quality |
| Sensor Support | Reads GM/Continental sensor via digital input |
If you're unsure:
👉 Contact RM Racing Electronics customer service or check your sensor's technical documentation for guidance.