My 2003 Ford Expedition is showing multiple misfire codes: P0174 (rich mixture bank 2), P0302, P0300 (random/multiple cylinder misfires), and P0306. I've already replaced the coil and spark plug for cylinder 2, but the issue persists. The P0300 and P0306 codes appeared today despite these repairs. I suspect a deeper underlying problem such as fuel delivery or sensor issues.
Confirmed it's a 5.4L engine. I've sprayed around all potential vacuum lines and found no leaks.
If there are no vacuum leaks, clean the Mass Air Flow (MAF) sensor using a dedicated MAF cleaner. After cleaning, monitor fuel trims via an OBD2 scanner. If unavailable, check fuel pressure in psi. Additionally, consider using a fuel system treatment like Techron or Seafoam to improve combustion efficiency.
Note: The codes listed (P2101, P2801, P3001, C1000, P0500, P1100) are from a different vehicle — a 2010 Ford Expedition ED Power. These do not apply to the original 2003 model and may be a mix-up or incorrect reference.
Check for vacuum leaks in bank 2. This is common on 5.4L engines. Reference: https://www.obd-codes.com/p0174