EFII System32
ATA Chapter 73 — N720AK Systems Reference
Overview
The EFII System32 provides complete electronic engine management for N720AK — both fuel injection and ignition. This is a fundamentally different architecture from traditional magneto/mechanical fuel injection systems. The System32 replaces the mechanical fuel servo, magnetos, and mixture cable with ECU-controlled port fuel injection and electronic ignition.
Components
| Component | Part Number | Supplier | Notes |
|---|---|---|---|
| ECU (x2) | System32 | flyEFII | Dual redundant |
| Coil packs | One per cylinder | ||
| Fuel injectors (x6) | PMI | flyEFII | 7075 aluminum, 60lb std / 80lb race. Install in 1/8NPT primer ports, PTFE pipe dope. 1/4NPT fuel rail T fitting. |
| Fuel pumps (x2) | FPM-1 | flyEFII | Dual Walbro GSL393, 400HP each, 5A/pump. AN-6 fittings. See Fuel System |
| Throttle body adapter | TBFA-1 | flyEFII | 3 1/4“ snout, silicone coupler to 3“ adapter. 5.5“ total length (same as Bendix servo). |
| System32 controller | flyEFII | Panel-mounted display/control |
How It Works
Electronic Fuel Injection
The System32 ECU controls fuel delivery through port fuel injectors. It uses sensor inputs (MAP, RPM, temperatures, O2) to calculate injector pulse width. The mixture is automatically optimized — no mixture lever or manual leaning required.
The fuel system is a pressurized loop with MAP-referenced regulation. See Fuel System for complete fuel plumbing and regulator details.
Electronic Ignition
Dual redundant ignition with individual coil packs for each cylinder. The System32 provides:
- Variable ignition timing based on RPM, MAP, and temperature
- Redundant ECU operation — either ECU can run the engine independently
- Panel switch for manual ECU selection
Panel Controls
EFII System32 Switches:
- Ignition Select
- ECU Select
- Fuel Pump Mode (PMP 2)
- Start Battery Select
EFII Breakers (VPX channels):
| Breaker | Rating | Function |
|---|---|---|
| ECU 1 | 5 A | ECU 1 power |
| ECU 2 | 5 A | ECU 2 power |
| Ignition | 15 A | Ignition coil packs |
| Fuel Pump | 10 A | Electric fuel pump |
Annunciator Lamps:
| Lamp | Color | Function |
|---|---|---|
| ECU 1 | Green | ECU 1 active |
| ECU 2 | Green | ECU 2 active |
| Primary Pump | Green | Primary fuel pump running |
| Secondary Pump | Amber | Backup fuel pump activated |
Fuel Compatibility
The EFII System32 supports both 100LL and premium automotive gasoline (mogas), with or without ethanol. The standard mapping handles compression up to 9:1 (N720AK’s configuration). Key limitations for mogas:
- Altitude limit: Stay below 8,000 ft on mogas (higher vapor pressure than avgas)
- Temperature limit: Do not use mogas in OAT above 100°F
- High terrain: Use 100LL when flying over high terrain
- Auto gas reaches its vapor point more easily than avgas at altitude and in heat
9:1 compression provides the best balance of performance, reliability, and fuel flexibility.
Source: flyEFII forum — VAF thread #157554
Tuning
Wiring
Diagnostics
Inspection & Maintenance
References
- EFII System32 Installation Manual (Rev 9-13)
- EFII System32 Operating Procedures (12-20)
- EFII System32 Fuel Flow & RPM Config (Rev 10-19)
- EFII System32 Initial Tuning — CSP (Rev 6-20)
- EFII Bus Manager Installation Instructions
- Fuel System — Regulator Diagnostics — fuel pressure analysis
- PLX DM-6 Multi Gauge User Guide
- PLX SM-AFR Gen2 User Guide
- PLX SM-AFR Gen4 Sensor Health Diagnostics — O2 sensor health: replace if <50%. Reaction time: <150ms excellent, >251ms poor. Requires DM-6 V2.0+.
- EFII Port Mount Injector (PMI) Installation
- EFII Throttle Body Flange Adapter (TBFA-1)
- EFII Dual Fuel Pump Module (FPM-1) — Dual Walbro GSL393, 400HP each, 5A/pump, AN-6 fittings. 10A breaker per pump or 20A shared.