wdgold

I know this has been rehashed over and over but there are so many suggested fixes on this issue, so I will get as specific as I can to hopefully avoid getting into throwing a lot of parts and money into this.

-I had a severe engine hesitation, jerking sensation at a certain speed RPM especially when in over drive. No engine service light came in at all, so no codes to detect.
-I changed the plugs out with motorcraft plugs and the problem went away.
-Ok, now after that I put in the chevron techron fuel cleaner with my next fill up and it ran great.
- The next time I filled up with gas I started having misfire issues, this was not the same problem I had before I installed the new plugs, a #4 misfire code was detected.
- After troubleshooting I installed a new plug in #4 and the code went away and ran fine until my next tank fill and then immediately after I filled up the misfire came back again except this time it was #5 code.

I want to stress that both times it happened it was immediately after I filled up with gas. After reading dozens of potential fixes for a misfire I am focusing on fuel evap issue, fuel pressure sensor or cat issue. Looking for answers.

Thank you

ieattacos

Possible faulty coil?

wdgold

When I changed plugs I inspected and tested all the coils and they looked really good. When I was dealing with #4 misfire I actually swapped coil pack with another cylinder and the problem din not follow the coil.

tareed94

When you did the plugs did you replace all the boots? I can't imagine it's fuel evap or a cat issue since it isn't staying with the same cylinder. Especially since #4 and #5 are on different banks.

wdgold

No I did not, didn't think you could change the boots w/o buying the coil. Whats really throwing me off with this whole thing is the fact it happens right after fuel fill up.

tareed94

I'd suggest changing all of the boots, it'll take a while since the truck is all put back together but I think it's only like $20. They're not very expensive, just make sure to use dielectric grease in them. I'm curious if it's just a coincidence that it's right after a fuel fill up. I can't think of anything that would be affected by adding fuel that wouldn't act up in other conditions.

Edit: I was way off on the price as they're about $10 each... http://www.oreillyauto.com/site/c/de...3758&ppt=C0334

wdgold

Exactly my thought, I will change the boots and see what happens.

connorfx4

Don't just change the boots. Make sure to change the springs too. You can order a set of 8 boots and springs online for around $30

tareed94

The Motorcraft boots come with springs if I remember correctly.

dsa

I have a 2005 5.4 and basically had the same problem. It gave me a fit trying to determine the cause of the misfire. Finally I broke down and replaced the coil packs. I got them on ebay and I think I paid like 56 dollars for all 8, brand new. Never had the problem since. Still to this day don't know which cylinder was misfiring and why. But its been about 4 months and no misfires.