I can't help with actual knowledge, but Gemini comes up with this. Maybe somewhere to start??
Hopefully someone with experience of similar will chime in...
Potential Causes for the Breakup
- Ignition Coil Strength: Are you still on stock coils? At 18psi, the stock FD coils often struggle. Most Link ECU users upgrade to IGBT Smart Coils (like the AEM/Mercury IGN-1A). If your coils are tired, they cannot punch through 18psi + Water at high RPM.
- Spark Plug Gap: If you use "surface discharge" plugs (like the BUR9EQP), you can't gap them. If you move to a standard electrode plug (like the B10EGV), you must gap them down—usually to 0.020" – 0.022"—to prevent the spark from being extinguished by the boost.
- The "Drowned" Rotor: If your WI nozzle is too large or the pump trigger is set too low in the RPM/Boost range, the water can foul the plugs during the transition, leading to the carbon deposits you saw.
- Grounding: Rotaries are notoriously sensitive to electrical noise. Ensure your engine block is grounded directly to the chassis and battery with heavy-gauge wire. Bad grounds often manifest as "breakup" right when electrical load is highest (high RPM).
Next Steps
- Swap the plugs: Start with a fresh set of NGK 9s or 10s.
- Check Lead Resistance: While replacing leads, ensure they are clicked firmly onto the coils and plugs; the FD vibration can sometimes wiggle them loose.
- Log the Link ECU: Do a 3rd gear pull (if safe) and look at your Battery Voltage and Trigger Errors. If voltage drops or you see trigger errors at 6k+, it's an electrical/sensor issue, not a fuel issue.
________________________________________________________________________________________
Since you are running
18psi with water injection, upgrading to
IGN-1A (Smart Coils) is the single best move you can make for ignition reliability. They are the industry standard for high-boost rotaries because they can provide a massive spark that won't "blow out."
However, because these coils are so powerful, they can actually overheat and melt if the
Dwell Time is set too high in your Link ECU.
1. Recommended Dwell Settings for IGN-1A
In your Link G4+ or G4X software, you should set up a
Dwell Table based on
Battery Voltage. For a high-boost 13B, use these targets:
| Battery Voltage | Dwell Time (ms) |
| 10V | 5.0 ms |
| 12V | 4.5 ms |
| 14V (Running) | 4.0 ms |
| 15V | 3.8 ms |
- Crucial Note: Do not exceed 4.5ms of dwell on a rotary unless you are making a qualifying pass. Rotaries fire twice as often as a 4-stroke engine; at high RPM, the "duty cycle" of the coil becomes very high. Over-dwelling them will cause them to overheat and fail prematurely.
2. Wiring & Hardware Requirements
The IGN-1A coils pull a lot of current (up to 15 amps each at peak). If you just wire them into the stock harness, you won't get the benefit and might melt wires.
- Dedicated Grounding: Each coil has multiple grounds. The High Current Ground (Pin C) must go directly to the Engine Rotor Housing. The Signal Ground (Pin B) must go to the ECU Signal Ground.
- Relay Power: Feed the coils directly from the battery via a dedicated 30A or 40A relay triggered by the ignition switch.
- Leading/Trailing: Ensure your Link ECU is configured for "Wasted Spark" on Leading if you are using the stock trigger wheel, or "Direct Fire" if you have an aftermarket trigger kit (like a Full Function Engineering kit).
3. Check for "Trigger Errors"
While you're in the Link software, look at the
Runtime Values (F12) and watch the
Trigger 1 Counter and
Trigger Errors.
- If the "Trigger Errors" count increases when you hit that 6.5k RPM wall, the ECU is losing track of where the eccentric shaft is.
- This is often caused by the stock "Mag" (Reluctor) sensors picking up interference from the spark plug wires. Keeping your new leads away from the CAS (Crank Angle Sensor) wires is vital.
4. Water Injection "Quenching"
Since you found fouled plugs, check your
Injection Start point.
- If you are spraying at full tilt by 6k RPM, you might be over-saturating the mixture.
- Try a pull with the Water Injection temporarily disabled (or lower the boost to 10-12psi) to see if the breakup disappears. If it clears up, your nozzle is too large or your pump is kicking in too hard too early.
