← Back to list

P1131, P1151, P0174, P0304, P0306 - Diagnosis and Fixes for 2000 Ford Expedition with 145K Miles

Model: 2000 Ford Expedition Fault Code: P0174 Posted: 2007-12-10 16:42

I'm experiencing multiple OBD-II fault codes on my 2000 Ford Expedition: P1131, P1151, P0174, P0304, and P0306. The vehicle has accumulated 145,000 miles and is running roughly, particularly around 1,500 RPM. Initially, I only had a P0304 code indicating a misfire in cylinder 4. I replaced the spark plug and coil pack (COP), which improved performance temporarily during a test drive—but symptoms have since returned. I did not clear the fault codes after the replacement, which may have contributed to ongoing issues. The spark plug I installed appeared whiteish-pink, suggesting a lean condition. In addition, I've already replaced the PCV valve and its associated elbow. For P1131 and P1151, the instrument panel displays 'Manufacturer Control Fuel Air Metering,' indicating potential issues with fuel air mixture control. I'm seeking advice on how to properly diagnose and resolve these codes. Any insights into possible root causes or next steps would be greatly appreciated. Thanks, Bea

Related fault codes
P0174P0304P1131P1151
Comments (7)
Anonymous 2007-12-10 16:52

Could a vacuum leak in the intake manifold or intake gasket be causing the issue? Or is a dirty Mass Air Flow (MAF) sensor possible?

Anonymous 2007-12-10 17:12

Thanks for the input, Jeff. I've inspected the MAF sensor inside the air intake and it appears clean. Regarding the intake gasket—how should I go about checking for leaks? It seems difficult to access, so I'm not sure if this is the right direction. Thanks again, Bea

Anonymous 2007-12-11 19:15

I cleaned the MAF sensor using CRC MAF cleaner. The engine runs slightly smoother now, but it's still rough—especially at idle and around 1,500 RPM. I've also performed a vacuum leak check with no visible signs of leaks. Do I need to reset the Powertrain Control Module (PCM), or will allowing time for retraining be sufficient? Thanks, Bea

Anonymous 2007-12-13 18:34

I now only have the original P0304 code. I replaced both the spark plug and coil pack, and confirmed that spark is present. The 2000 Ford Expedition still runs very rough between 1,000 and 2,000 RPM. Can anyone recommend a way to test fuel injectors or suggest other potential causes? Thanks, Bea

Anonymous 2007-12-14 15:25

To check fuel injector performance: remove the entire fuel rail while keeping the injectors connected, and have someone crank the engine. You should observe a fine mist spray from each injector—similar to hairspray. However, especially with plastic intake manifolds common on this model, it's critical to first inspect for vacuum or intake leaks. You can perform both checks simultaneously using WD-40 by spraying it around all suspected connections and watching for bubbles or hissing sounds.

Anonymous 2007-12-15 11:05

Thanks! Could you explain how to use WD-40 to detect vacuum or intake leaks? I've never done this before. Bea

Anonymous 2007-12-15 11:54

Check your Haynes or Chilton repair manual for detailed instructions—those books cover the exact procedures. If you don't have one, search online using keywords like 'how to test intake vacuum leaks with WD-40' for step-by-step guidance.