High Positive Fuel Trim 03 Explorer 4.0L V6

[Dragon22re]

Hi all. I am having some trouble with my explorer with bad fuel millage and decreased performance under load. It currently has 124000 miles on it, but I am unable to figure out the problem.

Looking at the real time data I have noticed that the LTFT on both banks are about 20%. Also I checked the fuel pressure and is good, around 60 PSI under load and idle. Also vacuum is 18 in HG at idle with no decrease under load. I tested the car to since I needed to do a tune up I change a few parts. Below I have created a list.

• PCM updated to the latest software
• Intake Gaskets (Felpro brand)
• PCV valve (motorcraft brand)
• ignition coil (motorcraft brand)
• spark plugs (motorcraft brand)
• Spark plug wires (motorcraft brand)
• O2 sensor for upstream bank 1 and 2 (motorcraft brand)
• Camshaft sensor
• Crankshaft sensor
• TPS (motorcraft brand)
• MAF (motorcraft brand)
• EGR Valve (Napa)
• DPFE sensor (Motorcraft Band)
• Coolant Temp Sensor (motorcraft brand)
• Air Filter (motorcraft brand)
• Fuel Filter (motorcraft brand)
• Fuel Injectors (motorcraft brand)

I am really out of ideas and would like any suggestions to address the issue.

 

[Dragon22re]

I also changed the brake booster and completely checked the car for vac leaks using propane, starting fuel, and water. I have noticed that the fuel trim increase under load. Recently I had the alternator go bad on my and I changed that along with a new battery. Could that be something that could be related? I have been trying to address the problem for the past 6 month to no avail. Any feedback would be greatly appreciated.

 

[Dragon22re]

I also have noticed that after reseting the PCM and preforming the learning procedure at idle the STFT will start out at 0, but then will increase as the truck warms up and then increases the LTFT. Also there is no CEL.

 

[Hugh Janus]

(dead link)
Good explanation of this condition.