So mostly just wanted to share an experience incase it might help anyone...
I bought my truck in Aug of 2012 and it will be going onto PCV valve number 3 since new on Tuesday when the part comes in. While this is getting slightly annoying, its only $32.00 so I am really not losing any sleep over that. Where the problem comes from is the driveability issues that stem from vacuum leaks.
Last spring whn I replaced my first one the wife had noticed some smoke coming from the tailpipe and after poking around a bunch I noticed the passenger side PCV vent into the intake had some oil in it. Pulled the valve out and gave it a test, no restriction in either direction as it should have.
I went online and found that the Coyote Mustang crowd are using modified GT500 PCV valves. Those come with a heating element from the get go and need to be cutoff. I found that the new 6.2L F150's use the same style valve minus the heater element. They are using that one as it allows less air to make it back into the intake and in theory less oil.
That worked fine for another year and I am back to square one, replacing with the proper valve. Trying to out smart it go me nowhere.
This spring though I have been having much worse driveability issues than just some smoke on strong acceleration. The truck was getting very hard to start when cold and the idle was getting even worse, though really it hasn't ever been all that great.
I capped off the intake and let the PCV vent to the atmosphere (through a catch can) as I am still waiting for the new part to come in. I also reset the Keep Alive Memory to reset the fuel adapative settings. After startup and a few minutes of relearn process in the driveway I got the results I was hoping for.
The Virtual Fuel Composition Sensor went from reading 85% ethanol (on fuel that says it has 0% for the last 6 or more fillups) down to 3.9%, and the short term fuel trims went from reading -20% on both banks at idle to +/- 1%.
The cold startups are sorted out and the truck idles better than I can ever remember.
This was stemmed from very frequent short drives with lots of autostart time in winter months that get down well below 0 for months at a time. While I know my case sounds a lot worse than most with the 5.0L idle issues maybe it will help save someone some contemplation time.
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