2003 Ford F150 5.4L Running Rough with P1139 Fuel Air Management System Fault
I initially thought my 2003 Ford F150 5.4L was experiencing a coil pack issue, so I replaced all the coil packs on the passenger side (bank 1), including both positions 1 and 2 — more than necessary. However, the truck is still running very rough. I've used a Mac Tools OBD2 scanner, cleared the fault codes, and after driving the vehicle, no errors appear in real time. The issue persists. The only code I initially received was P1139, which indicates a 'fuel air management system failure'. I'm not entirely sure what this system entails or how it affects engine performance. I've already checked all accessible wiring and ground connections with no issues found. My question is: What exactly does the fuel air management system control? And more importantly, how can I diagnose and resolve this issue if the PCM is responsible for triggering coil packs?
Could you please share engine parameters such as LT/ST fuel trims, MAF sensor readings, O2 sensor data, and fuel pressure? Additionally, providing the freeze frame data from P1139 would be very helpful in diagnosing the root cause. Remember, coil packs are triggered by the Powertrain Control Module (PCM), so the issue may not be with the coils themselves but rather with the PCM or its related systems.