Constellation of Problems - 2011 Ford Fiesta

[jeosu660]

I drive a 2011 Ford Fiesta SE - Manual transmission. I have experienced a hilarious constellation of problems with this car, but the engine keeps going so I continue to run it! I am looking for ideas on what to do to get it back in working order.

First issue:
1) I get an on again, off again P0068 error code. It registers at random times, but turns off after about 2 days. Not sure what I should first.
2) The air conditioning went out several years back immediately after I was accelterating quickly to get on a highway; third gear, +5000 RPM; A/C goes out, never comes back. I take it to the mechanic...the mechanic replaces the entire a/c system, but says the system is not getting power. Says the a/c system works with power, but its not receiving power from the car; blames the PCM. I order a PCM and install it myself (get it programmed and everything). Still no power to the A/C. I still have no A/C.
3) After issue #2 started, I also started getting engine misfire errors in spark plug #2 under heavy acceleration (+4500 RPM). I replaced all the spark plugs, same #2 spark plug error. I replaced all of the ignition wires. The misfire moved from #2 to plug #3. This issue possibly has resolved itself after the fuse box was replaced due to recall notification for corroded fuse box but honestly, I've not really pushed it to find out. (This did not fix A/C though)
4) The radio column occasionally turns on and off, resetting itself at random times. Sometimes when I am driving, sometime at start up....anywhere. There is some type of electrical ghost, i assume.

Things that I have done/check:
1) Replaced the fuse box in the engine bay (recall)
2) Checked every fuse, replaced several that looked worse than others
3) replaced PCM
4) replaced all A/C system
5) Battery has been replaced
6) Alternator tested and OK

Does anyone have any ideas that might tie these symptoms together?

 

[econoboxrocks]

The only thing I can think of is checking your grounds. That's a known weak spot for these cars.

 

[Handy Andy]

I second that, considering the P0068 is "Generic" for MAF and MAP sensors that contradict each other - cause this code.

To me this leans back to @econoboxrocks suggestion of poor grounding - you own a 2011 - so you are experiencing a plethora of problems that more than likely are going to resolve themselves once you address grounds, or loose or poor connectors in the harness itself.

Running a motor up to 5 grand is not the issue, the issue comes from the 5,000 RPM on a consistent daily basis for long term points of drive time - this also can force issues with timing errors caused by high cycle high RPM and high torque developing at the same time - causing vibrations - which won't hurt if they are just moments - but long term vibrations can cause a "resonance" which some mechanics consider key problems with sensors failing to detect correctly and then lead to mis-fires and if the vibrations and speed sweep into them are held for long periods of time, the sensors can lose their seal, alignment or worse fail by their innards being struck by the detection or occultation wheel or in hall-effect devices, the magnets and sensors striking each other pulverizing them both.

That kind of vibration on older wiring can lead to internal breakage. Wire failure - like the fusible links - they can open and then the sensors can't send the right data needed for the PCM to process. This vibration may have shaken loose this harness and now you are experiencing the results of that condition.

The only reason why you don't have the Check Engine light is due to the complexity of the condition and the faults steps in occurring can clear on their own to a degree, but not all of them.

Mis-fires are a leading indicator of eventual failure in the timing belts or chains used to drive the cam and sensors on them.