Ford Repair Questions? Ask a Mechanic for Answers ASAP
These codes are caused either by a vacuum leak, low fuel pressure or a bad Mass Air Flow Sensor. Inspect the vacuum lines and the PCV hoses from the intake to the valve cover. Check the rubber elbows for cracks, stickiness and collapsed hoses. Then check the fuel pressure.
Check for vacuum leaks on the PCV system first.
Welcome, I'm Chris (aka Moose) I prefer to work when others don't, I am here around lunch and after dinner till after midnight.
The previous tech has opted out. Would you like me to help with this air fuel ratio issue?
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Hello again Chris here,
At operating temp in park what is the short term fuel trim on both banks?
If there was a vacuum leak your short and long term trims would be pegged at the max +20. The spec is +/-10. Your average is not out of specs meaning this is not a vacuum leak to blame.
The PCM uses the O2 sensor reading to determine how long to pulse the fuel injectors. That would change the fuel trim readings. Without the trim readings out of whack and no O2 codes I can not see a way to blame the O2 sensors.
I did not even remember about the previous codes mentioned long ago from the time delay between responses. I can not keep up efficiently on the topic at hand when there are days between posts. I will opt out and see if another wants to help.
Try unplugging the MAF (Mass Air Flow) sensor and drive the vehicle. See if you get the same codes and same drivability problems. A bad MAF can cause all the same problems.
Plug the MAF back in, clear the codes and loosen the exhaust pipes from the manifolds and run the vehicle. It will be noisy, but see if thing change. This will check for clogged exhaust/bad converters.