2001 5.4 dogs when low and throwing codes that don't make sense

[eastmonsoon]

Hey all,
I have a 2001 Expy 5.4 that I just changed the plugs in for the second time. It has a reall misfire at all RPM's and shakes and judders through the rev band. The first time i goofed and put in Bosch +4's upon the advice of a local mechanic, then it started coding both lean on banks 1 & 2 and a misfire on cylinder #6. I read more on this forum and then change out to Autolite platinum OEM plugs and I am still getting lean on banks 1 & @ but no misfire on cylinder #6. Once i use the code reader to remove the codes it runs fine for about 15-45 minutes of actual run time.

My how to question is this: How do I test the vacuum lins property and the PCM?

 

[FordandPolaris]

http://www.expeditionforum.com/f27/rough-idle-p0171-p0174-heres-what-you-need-check-first-4926/

Check this, this was what my lean code was from.

 

[toms89]

Hey all,
I have a 2001 Expy 5.4 that I just changed the plugs in for the second time. It has a reall misfire at all RPM's and shakes and judders through the rev band. The first time i goofed and put in Bosch +4's upon the advice of a local mechanic, then it started coding both lean on banks 1 & 2 and a misfire on cylinder #6. I read more on this forum and then change out to Autolite platinum OEM plugs and I am still getting lean on banks 1 & @ but no misfire on cylinder #6. Once i use the code reader to remove the codes it runs fine for about 15-45 minutes of actual run time.

My how to question is this: How do I test the vacuum lins property and the PCM?

Not sure when the codes initially started based on your post. If it was only after changing plugs it could very well be ignition issues. Your O2 sensors will read lean when you have a misfire due to unburned O2 passing into the exhaust.

 

[eastmonsoon]

Yeah, I had just posted when I saw the sticky about P0171, etc so I was trying to delete this thread. and yes, it did start after changing plugs and I am pursuing a vacuum leak from either the PCV or the multitude of lines in the engine bay. I kinda decided that the PCM is not the culprit after reading the above referenced post.