2005 Ford F150 P0172 P0304 P2196 Fault: Rich Mix, Misfire, White Smoke and Bad Odor
I have a 2005 Ford F15-0 with persistent engine issues. Three months ago I replaced the spark plugs, but now the vehicle is idling poorly at stops and displaying fault codes P0172 (rich fuel mixture), P0304 (cylinder 4 misfire), and P2196 (fuel trim malfunction). I've never used a scan tool before, but the OBD2 scanner shows these codes consistently. The engine emits a strong gasoline smell, and there are occasional small puffs of white smoke when idling. These symptoms suggest an overly rich fuel mixture and a misfire in cylinder 4, which may be related to spark plug condition or fuel system performance.
The engine fault codes indicate the system is running too rich—excess fuel is being injected. Additionally, P0304 points to a misfire in cylinder #4. I recommend starting with cylinder #4: remove and inspect the spark plug for signs of wetness, dryness, black or tan deposits—all of which can point to incorrect combustion or fuel delivery. Perform a fuel pressure leak-down test at engine idle (KOEO condition). Also, ensure you're using OEM-quality spark plugs—part-store replacements may not meet specifications. Note: cylinder numbering can vary by Ford model year and engine type; confirm the specific engine configuration for accurate diagnosis.